Liquidus temperature 943 °C (1730 °F) Electrical Properties Solidus temperature 854 °C (1570 °F) Electrical conductivity Volumetric, 11.5% IACS at 20 °C (68 °F) Incipient melting temperature Pb, 315 °C (600 °F) Magnetic Properties Coefficient of linear thermal expansion 18.5 Magnetic permeability 1.0 μm/m · K (10.3 μin./in · °F) at 20 to 204 °C (68 to 400 °F) Specific heat 376 J/kg · K (0.09 Btu/lb · °F) Fabrication Characteristics Machinability 80% of C36000 (free-cutting brass) Thermal conductivity 52 W/m · K (30 Btu/ft · h · °F) at 20 °C (68 °F) C94300 70Cu-5Sn-25Pb Commercial Names Tensile properties Typical data for sandcast test bars: Common name High-leaded tin bronze, soft bronze, 70-5- 25 tensile strength, 185 MPa (27 ksi); yield strength, 90 MPa (13 ksi) at 0.5% extension under load; elongation, 10% in 50 mm (2 in.); reduction in area, 8% Specifications Compressive properties Typical compressive strength: 76 ASTM B 584, B 66, B 271, B 505, B 30 MPa (11 ksi) at permanent set of 0.1%; 160 MPa (23 ksi) at permanent set of 10% SAE J462 (CA943) Hardness 48 HB Government QQ-L-225, Alloy 18; MIL-B-16261, Alloy Elastic modulus Tension, 72.4 GPa (10.5 × 10 psi) V Other Ingot code number 322 Chemical Composition Impact strength Izod, J (5 ft · lbf) Mass Characteristics 3 Density 9.29 g/cm (0.336 lb/in ) at 20 °C (68 °F) Composition limits 68.5 to 73.5 Cu, 4.5 to 6.0 Sn, 22.0 to in./ft) 25.0 Pb, 0.50 Zn max, 0.70 Ni max, 0.15 Fe max, 0.70 Sb max, 0.05 P max, 0.08 S max Patternmaker's shrinkage 11 mm/m ( Supplementary composition limits In determining Cu, Thermal Properties minimum may be calculated as Cu + Ni 0.35 Fe max when used for steel-backed bearings 1.5 P max for continuous castings Solidus temperature 900 °C (1650 °F) Applications Incipient melting temperature Pb, 315 °C (600 °F) Specific heat 376 J/kg · K (0.09 Btu/lb · °F) at 20 °C (68 Typical uses Bearings under light loads and high speed, °F) driving boxes, railroad bearings Mechanical Properties Thermal conductivity 62.7 W/m · K (36.2 Btu/ft · h · °F) at 20 °C (68 °F) Electrical Properties Electrical conductivity Volumetric, 9% IACS at 20 °C (68 Fabrication Characteristics °F) Machinability 80% of C36000 (free-cutting brass) Magnetic Properties Magnetic permeability 1.0 C94500 73Cu-7Sn-20Pb Commercial Names Impact strength Izod, 5.4 J (4.0 ft · lbf) Common name Medium bronze Mass Characteristics Specifications Density 9.4 g/cm (0.34 lb/in ) at 20 °C (68 °F) ASTM Sand castings: B 66; ingot: B 30 Volume change on freezing 1.1% Government QQ-L-225, Alloy 15; MIL-B-16261, Thermal Properties 3 Alloy I Liquidus temperature 940 °C (1725 °F) Chemical Composition Solidus temperature 800 °C (1475 °F) Composition limits 6.0 to 8.0 Sn, 16 to 22 Pb, 1.2 Zn max, 1.0 Ni max, 0.8 Sb max, 0.005 Al max, 0.15 Fe max, 0.5 P max (1.5 P max for continuous castings), 0.08 S max, 0.005 Si max, bal Cu Incipient melting temperature 315 °C (600 °F) Coefficient of linear thermal expansion 18.5 Applications μm/m · K (10.3 μin./in · °F) at 20 to 200 °C (68 to 392 °F) Typical uses Locomotive wearing parts, high-load Specific heat 376 J/kg · K (0.09 Btu/lb · °F) at 20 °C low-speed bearings (68 °F) Mechanical Properties Thermal conductivity 52 W/m · K (30 Btu/ft · h · °F) at 20 °C (68 °F) Tensile properties Typical Tensile strength, 170 MPa (25 ksi); yield strength, 83 MPa (12 ksi);elongation, 12% in 50 mm (2 in.) Electrical Properties Electrical conductivity Volumetric, 10% IACS at Compressive properties Compressive strength, 250 20 °C (68 °F) MPa (36 ksi) Magnetic Properties Hardness 50 HB Magnetic permeability 1.0 Elastic modulus Tension, 72 GPa (10.5 × 10 psi); shear, 90 GPa (13 × 106 psi) Fabrication Characteristics Fatigue strength Rotating beam, 69 MPa (10 ksi) at Machinability 80% of C36000 (free-cutting brass) 108 cycles C95200 88Cu-3Fe-9Al Commercial Names Composition limits 86 Cu min, 8.5 to 9.5 Al, 2.5 to 4.0 Fe, 1.0 max other (total) Previous trade name Ampco Al Common name Aluminum bronze 9A; 88-3-9 Specifications ASME Sand castings: SB148; centrifugal castings: SB271 ASTM Sand castings: B 148; centrifugal castings; B 271; continuous castings; B 505; ingot: B 30 Consequence of exceeding impurity limits Possible hot shortness and/or hot cracking, embrittlement, and reduced soundness of castings Applications Typical uses Acid-resisting pumps, bearings, bushings, gears, valve seats, guides, plungers, pump rods, pickling hooks, nonsparking hardware Precautions in use Not suitable for use in oxidizing SAE J462 acids Government Mechanical Properties Centrifugal, sand, and continuous castings; QQ-C-390; sand castings: MIL-C-22229 Other Ingot code number 415 Chemical Composition Tensile properties Typical data for sand-cast test bars: tensile strength, 550 MPa (80 ksi); yield strength, 185 MPa (27 ksi); elongation, 35% in 50 mm (2 in.) See also Fig 44 Fig 44 Typical short-time tensile properties of C95200, as-cast Hardness 64 HRB; 125 HB (3000 kg load) Fatigue strength Rotating beam, 150 MPa (22 ksi) at 108 cycles Poisson's ratio 0.31 Creep-rupture Elastic modulus Tension, 105 GPa (15 × 10 psi); shear, 39 GPa (5.7 × 106 psi) Impact strength Charpy keyhole, 27 J (20 ft · lbf) at -18 to 38 °C (0 to 100 °F); Izod, 40 J (30 ft · lbf) at -18 to 38 °C (0 to 100 °F) characteristics Limiting creep stress for 10-5%/h: 145 MPa (21 ksi) at 230 °C (450 °F); 54 MPa (7.9 ksi) at 315 °C (600 °F) See also Fig 45 Fig 45 Typical creep properties of C95200, as-cast Structure Electrical Properties Microstructure Electrical conductivity Volumetric, 12% IACS at As cast, the microstructure is primarily fcc alpha, with precipitates of iron-rich alpha in the form of rosettes and spheres Depending on the cooling rate, small amounts of metastable cph beta or alpha-gamma eutectoid decomposition products may be present Annealing followed by rapid cooling reduces the amount of residual beta to about 5% of the apparent volume Metallographic etchant Acid ferric chloride (10% HCl, 5% FeCl3) 20 °C (68 °F) Electrical resistivity 144 nΩ · m at 20 °C (68 °F) Magnetic Properties Magnetic permeability 1.20 at 16,000 A/m (200 oersteds) Chemical Properties Mass Characteristics General corrosion behavior C95200 has generally Density 7.64 g/cm (0.276 lb/in ) at 20 °C (68 °F) Volume change on freezing Approximately 1.7% contraction Patternmaker's shrinkage 2% Thermal Properties fair resistance to attack in nonoxidizing mineral acids such as sulfuric, hydrochloric, and phosphoric, and in alkalies such as sodium and potassium hydroxide Cast components are used successfully in systems for seawater, brackish water, and potable water The alloy resists many organic acids, including acetic and lactic, plus all esters and ethers Moist ammonia atmospheres can cause stress-corrosion cracking Fabrication Characteristics Liquidus temperature 1045 °C (1915 °F) Machinability 20% of C36000 (free-cutting brass) Solidus temperature 1040 °C (1905 °F) Coefficient of linear thermal expansion 16.2 μm/m · K (9.0 μin./in · °F) at 20 to 300 °C (68 to 572 °F) Specific heat 380 J/kg · K (0.091 Btu/lb · °F) at 20 °C (68 °F) Carbide or tool steel cutters may be used Good surface finish and precision attainable with all conventional methods Typical conditions using tool steel cutters: roughing speed, 105 m/min (350 ft/min) with a feed of 0.3 mm/rev (0.011 in./rev); finishing speed, 350 m/min (1150 ft/min) with a feed of 0.15 mm/rev (0.006 in./rev) Annealing temperature 650 to 745 °C (1200 to 1375 °F) Thermal conductivity 50 W/m · K (29.1 Btu/ft · h · °F) at 20 °C (68 °F) C95300 89Cu-1Fe-10A1 Commercial Names ksi) Elastic limit: as-cast, 125 MPa (18 ksi); TQ50 temper, 205 MPa (30 ksi) Trade name Ampco B2 Hardness As-cast, 67 HRB; TQ50 temper, 81 HRB Common names Aluminum bronze 9B; 89-1-10 Poisson's ratio 0.314 Specifications Elastic modulus Tension, 110 GPa (16 × 106 psi); shear, 42 GPa (6.1 × 106 psi) ASTM Sand castings: B 148; centrifugal castings: B 271; continuous castings: B 505; ingots: B 30 Impact strength Cast and annealed: Charpy keyhole, 31 J (23 ft · lbf); Izod, 38 J (28 ft · lbf) at -20 to 100 °C (-5 to 212 °F) TQ50 temper: Charpy keyhole, 37 J (27 ft · lbf) at -20 to 100 °C (-5 to 212 °F) SAE J462 Government Centrifugal and sand castings: QQ-C-390; precision castings: MIL-C-11866, composition 22 Ingot identification number 415 Chemical Composition Composition limits 86 Cu min, 9.0 to 11.0 Al, 0.8 to 1.5 Fe, 1.0 max other (total) Consequence of exceeding impurity limits Possible hot shortness, loss of casting soundness, embrittlement, reduced response to heat treatment Applications Typical uses Pickling baskets, nuts, gears, steel mill slippers, marine equipment, welding jaws, nonsparking hardware Precautions in use Not suitable for exposure to oxidizing acids Prolonged heating in the 320 to 565 °C (610 to 1050 °F) range can result in a loss of ductility and notch toughness Structure Crystal structure Alpha phase, face-centered cubic; beta phase, close-packed hexagonal Microstructure As-cast and properly cooled or annealed, the structure is approximately 70% alpha and 30% metastable beta Quenched and tempered (TQ50 temper), the structure is largely tempered metastable beta martensite, but also contains both primary alpha and reprecipitated acicular alpha Mass Characteristics Density 7.53 g/cm3 (0.272 lb/in.3) at 20 °C (68 °F) Patternmaker's shrinkage 1.6% Thermal Properties Liquidus temperature 1045 °C (1915 °F) Solidus temperature 1040 °C (1905 °F) Mechanical Properties Coefficient of linear thermal expansion 16.2 μm/m · K (9.0 μin./in · °F) at 20 to 300 °C (68 to 572 °F) Tensile properties Minimum values As cast: tensile strength, 450 MPa (65 ksi); yield strength, 170 MPa (25 ksi); elongation, 20% in 50 mm (2 in.); reduction in area, 25% TQ50 temper: tensile strength, 550 MPa (80 ksi); yield strength, 275 MPa (40 ksi); elongation, 12% in 50 mm (2 in.); reduction in area, 14% Specific heat 375 J/kg · K (0.09 Btu/lb · °F) at 20 °C (68 °F) Compressive properties Compressive ultimate strength: as-cast, 760 MPa (110 ksi); TQ50 temper, 825 MPa (120 Thermal conductivity 63 W/m · K (36 Btu/ft · h · °F) at 20 °C (68 °F); temperature coefficient, 0.12 W/m · K per K at 20 °C (68 °F) Electrical Properties Electrical conductivity Volumetric, 13% IACS at 20 °C (68 °F) alloy shows characteristic resistance to nonoxidizing mineral acids, neutral salt solutions, seawater, brackish water, and some organic acids Electrical resistivity 133 nΩ · m at 20 °C (68 °F) Fabrication Characteristics Magnetic Properties Magnetic permeability 1.07 at field strength of kA/m Chemical Properties General corrosion behavior Corrosion characteristics of C95300 are slightly inferior to those of C95200, primarily because C95300 has more and larger beta areas Heat treatment enhances corrosion resistance, particularly in mediums that promote dealloying The Machinability 55% of C36000 (fire-cutting brass) Tool steel or carbide cutters may be used Good surface and precision finish may be obtained in the as-cast, cast and annealed, and TQ50 tempers Typical conditions using tool steel cutters: roughing speed, 90 m/min (300 ft/min) at a feed of 0.2 mm/rev (0.009 in./rev); finishing speed, 290 m/min (950 ft/min) at a feed of 0.1 mm/rev (0.004 in./rev) Annealing temperature 595 to 650 °C (1100 to 1200 °F) C95400 (85Cu-4Fe-11Al) and C95410 Commercial Names Cu + sum of named elements 99.5 Trade name Ampco C3 Consequence of exceeding impurity limits Common names Aluminum bronze 9C; G5; 85-4-11 Possible hot shortness, reduced casting soundness, embrittlement and loss of heat treating response Specifications Applications ASME Sand castings: SB148 Typical uses Pump impellers, bearings, gears, worms, bushings, valve seats and guides, rolling mill slippers, slides, nonsparking hardware ASTM Sand castings: B 148; centrifugal castings: B 271; continuous castings: B 505; ingots; B 30 Government QQ-C-390 Sand castings, MIL-C- 22229 (composition 6); investment castings, MIL-C15345 (Alloy 13); centrifugal castings, MIL-C-22087 (composition 8) Ingot identification number 415 Chemical Composition Composition limits of C95400 83 Cu, 10.0 to 11.5 Al, 3.0 to 5.0 Fe, 0.50 Mn max, 2.5 Ni max (+ Co), 0.5 max other (total) Composition limits of C95410 83.0 Cu min, 3.0 to 5.0 Fe, 1.5 to 2.5 Ni (including Co), 10.0 to 11.5 Al, 0.50 Mn max Precautions in use Not suitable for use in oxidizing acids Prolonged heating in the 320 to 565 °C (610 to 1050 °F) range can result in loss of ductility and notch toughness Mechanical Properties Tensile properties Minimum values As cast: tensile strength, 515 MPa (75 ksi); yield strength, 205 MPa (30 ksi); elongation, 12% in 50 mm (2 in.); reduction in area, 12% TQ50 temper: tensile strength, 620 MPa (90 ksi); yield strength, 310 MPa (45 ksi); elongation, 6% in 50 mm (2 in.), reduction in area, 6% See also Fig 46 Fig 46 Typical short-time tensile properties of C95400, as-cast Compressive properties Compressive strength, ultimate: as-cast, 940 MPa (136 ksi); TQ50 temper, 1070 MPa (155 ) temper: Charpy keyhole, J (7 ft · lbf); Izod, 15 J (11 ft · lbf) at 20 °C (68 °F) Fatigue strength Reverse bending, 240 MPa (35 ksi) Hardness As-cast, 83 HRB; TQ50 temper; 94 HRB at 108 cycles (TQ50 temper) Poisson's ratio 0.316 Creep-rupture Elastic modulus Tension, 110 GPa (16 × 10 psi); shear, 41 GPa (6.1 × 10 psi) characteristics Limiting creep stress at a strain rate of 10-5%/h: 115 MPa (17 ksi) at 230 °C (450 °F); 51 MPa (7.4 ksi) at 315 °C (600 °F); 30 MPa (4.4 ksi) at 370 °C (700 °F); 20 MPa (2.9 ksi) at 425 °C (800 °F) See also Fig 47 Impact strength As-cast: Charpy keyhole, 15 J (11 ft · lbf); Izod, 22 J (16 ft · lbf) at 20 °C (68 °F) TQ50 Fig 47 Typical creep properties of C95400, as-cast Structure Crystal structure Alpha, face-centered cubic; beta, Electrical resistivity 133 nΩ · m at 20 °C (68 °F) close-packed hexagonal Magnetic Properties Microstructure As-cast and annealed material normally consists of approximately 50% alpha and 50% metastable beta Under some conditions, eutectoid decomposition may produce an alpha-gamma-2 structure instead of the beta phase Quenched-and-tempered structures consist of fine acicular alpha crystals in a tempered beta matrix Magnetic permeability As-cast, 1.27 at field strength of 16 kA/m; TQ50 temper, 1.20 at field strength of 16 kA/m Chemical Properties General Solidus temperature 1025 °C (1880 °F) corrosion behavior C95400 has fair resistance to attack by nonoxidizing solutions of mineral acids such as sulfuric and phosphoric, as well as to neutral salts such as sodium chloride The alloy also resists acetic; lactic, and oxalic acids; organic solvents such as esters and ethers; and seawater, brackish water, and potable waters In some environments, C95400 can undergo dealloying caused by corrosive attack on the beta phase Heat treatment improves resistance to dealloying Moist ammonia environments may cause stress-corrosion cracking under high levels of applied stress Coefficient of linear thermal expansion 16.2 Fabrication Characteristics μm/m · K (9.0 μin./in · °F) at 20 to 300 °C (68 to 572 °F) Machinability 60% of C36000 (free-cutting brass.) Mass Characteristics 3 Density 7.45 g/cm (0.269 lb/in ) at 20 °C (68 °F) Patternmaker's shrinkage 1.6% Thermal Properties Liquidus temperature 1040 °C (1900 °F) Specific heat 420 J/kg · K (0.10 Btu/lb · °F) at 20 °C (68 °F) Thermal conductivity 59 W/m · K (34 Btu/ft · h · °F) at 20 °C (68 °F); temperature coefficient, 0.117 W/m · K per K at 20 °C (68 °F) Electrical Properties C95400, in either as-cast or TQ50 temper, is easily machined by all standard operations using high-strength tool steel or carbide cutters Typical conditions using tool steel cutters: roughening speed, 90 m/min (300 ft/min) at a feed of 0.34 mm/rev (0.011 in./rev); finishing speed, 290 m/min (950 ft/min) at a feed of 0.1 mm/rev (0.004 in./rev) Annealing temperature 620 °C (1150 °F) Electrical conductivity Volumetric, 13% IACS at 20 °C (68 °F) C95500 81Cu-4Fe-4Ni-11Al Commercial Names SAE J462 Previous trade name Ampco D4 Government QQ-C-390; centrifugal castings, MIL-C- Common names Aluminum bronze 9D; 415; 81-4-4-11 15345 (Alloy 14); sand castings, MIL-C-22229 (composition 6); investment castings, MIL-C-22087 (composition 8) Specifications AMS 4880 ASTM Sand castings: B 148; centrifugal castings: B 271; continuous castings: B 505: ingots: B 30 Ingot identification number 415 Chemical Composition Composition limits 78 Cu min, 10.0 to 11.5 Al, 3.0 to 5.0 Crystal structure Alpha, face-centered cubic; beta, close- Fe, 3.5 Mn max, 3.0 to 5.5 Ni (+ Co), 0.5 max other (total) packed hexagonal; kappa, ordered face-centered cubic Microstructure As-cast or annealed structures consist of Consequence of exceeding impurity limits Possible hot shortness in welding, embrittlement, increased quenchcracking susceptibility, possible loss of heat-treating response Excessive Si can cause machining difficulties Applications Typical uses Valve guides and seats in aircraft engines, corrosion-resistant parts, bushings, pickling hooks and baskets, agitators gears, worms, alpha crystals plus kappa precipitates, forming a pearlitic appearance Small areas of metastable beta may exist Heat-treated structures consist of tempered beta martensite with very fine reprecipitated alpha needles Some undissolved equiaxed alpha crystals may be evident, depending on the actual composition and quenching temperature Mass Characteristics 3 Density 7.53 g/cm (0.272 lb/in ) at 20 °C (68 °F) Precautions in use Not suitable for use in strong oxidizing acids Patternmaker's shrinkage 1.6% Mechanical Properties Thermal Properties Tensile properties Typical As-cast: tensile strength, 620 Liquidus temperature 1055 °C (1930 °F) MPa (90 ksi); yield strength, 275 MPa (40 ksi); elongation, 6% in 50 mm (2 in.); reduction area, 7% TQ50 temper: tensile strength, 760 MPa (110 ksi); yield strength, 415 MPa (60 ksi); elongation, 5% in 50 mm (2 in.); reduction in area, 5% Solidus temperature 1040 °C (1900 °F) Coefficient of linear thermal expansion 16.2 μm/m · K (9.0 μin./in · °F) at 20 to 300 °C (68 to 572 °F) Compressive properties As-cast: compressive strength, 895 Specific heat 418 J/kg · K (0.10 Btu/lb · °F) at 20 °C (68 MPa (130 ksi); compressive yield strength, 825 MPa (120 ksi) at a permanent set of 10%; elastic limit, 310 MPa (45 ksi) TQ50 temper; compressive strength, 1140 MPa (165 ksi); compressive yield strength, 1030 MPa (150 ksi) at a permanent set of 10%; elastic limit, 415 Mpa (60 ksi) °F) Hardness As-cast, 87 HRB; TQ50 temper, 96 HRB °C (68 °F) Electrical Properties Electrical conductivity Volumetric, 8.5% IACS at 20 °C (68 °F) Poisson's ratio 0.32 Elastic modulus Tension: as-cast, 110 GPa (16 × 10 psi); TQ50 temper, 115 GPa (17 × 10 psi) Shear as-cast, 42 GPa (6.1 × 106 psi); TQ50 temper, 44 GPa (6.4 × 106 psi) Impact strength Charpy keyhole, 14 J (10 ft · lbf); Izod, 18 J (13 ft · lbf) at 20 °C (68 °F) Fatigue strength Rotating beam, as-cast, 215 MPa (31 ksi) at 108 cycles; TQ50 temper, 260 MPa (38 ksi) at 108 cycles Creep-rupture characteristics Limiting creep stress at a strain rate of 10-5%/h: 72 MPa (10.5 ksi) at 315 °C (600 °F); 38 MPa (5.5 ksi) at 370 °C (700 °F); 17 MPa (2.5 ksi) at 425 °C (800 °F) Structure Thermal conductivity 42 W/m · K (24 Btu/ft · h · °F) at 20 Electrical resistivity 203 nΩ · m at 20 °C (68 °F) Magnetic Properties Magnetic permeability As-cast, 1.30 at field strength of 16 kA/m; TQ50 temper, 1.20 at field strength of 16 kA/m Chemical Properties General corrosion behavior Good cavitation resistance in salt water and fresh tap water Avoid nitric acid and strong aeration when using other acids Fabrication Characteristics Machinability 50% of C36000 (free-cutting brass) Heat treating reduces machinability in drilling and tapping operations Tool steel or carbide cutters may be used Typical conditions using tool steel cutters follow AZ31B-F 2.4t 288 550 1.5t M1A-F 4.8t 371 700 2.0t AZ80A-T5 8.3t 193 380 1.7t ZK60A-F 12t 288 550 2.0t ZK60A-T5 12t 204 400 6.6t Table 20 Form bending parameters for magnesium tubing Alloy Forming temperature Bend radius(a) °C ZK60A-F Alloy 4D 200 3D 21 70 4D 20 3D 21 70 6D 204 M1A-F 70 -7 AZ61A-F 21 93 AZ31B-F °F 400 4D 21 70 5D radius D/t = 17 AZ61A-F(c) Minimum bend at 21 °C (70 °F)(b) D/t = 5D D/t = D 2D AZ61A-F(d) D 2 D 2 D AZ31B-F(c) 6D 4D 3D AZ31B-F(d) 3D 2D 2D M1A-F(c) 6D 3D M1A-F(d) 6D 6D D 2 D (a) D, tube outside diameter Bend radius taken to axis of tube (b) Minimum bend radius for various D/t ratios at 21 °C (70 °F) D, tube outside diameter; t, wall thickness (c) Tubing unfilled before bending (d) Tubing filled with low-melting alloy (50% Bi, 26.7% Pb, 13.3% Sn, 10% Cd) before bending Joining of Magnesium Alloys Welding Magnesium alloys can be readily welded by gas metal arc welding and by resistance spot welding Rods of approximately the same composition as the base metal are generally satisfactory With alloys HM21A and HM31A, EZ33A rods give higher joint efficiencies (Table 21) Table 21 Weldability of magnesium alloys Alloy Thickness Welding rod Joint efficiency, % Joint ductility(a) mm in AZ31B-O 1.63 0.064 AZ61A, AZ92A 97 12.0 AZ31B-H24 1.63 0.064 AZ61A, AZ92A 88 10.0 ZE10A-O 1.63 0.064 AZ61A, AZ92A 94 7.0 ZE10A-H24 1.63 0.064 AZ61A, AZ92A 87 3.0 M1A-F 3.17 0.125 M1A 55 2.0 AZ31B-F 3.17 0.125 AZ61A, AZ92A 92 12.0 AZ61A-F 3.17 0.125 AZ61A, AZ92A 89 8.0 AZ80A-F 3.17 0.125 AZ61A, AZ92A 86 4.0 AZ63A-F 12.70 0.5 AZ63A 83 2.5 AZ63A-T4 12.70 0.5 AZ63A 70 5.0 AZ63A-T6 12.70 0.5 AZ63A 75 2.0 AZ92A-F 12.70 0.5 AZ92A 100 2.5 AZ92A-T4 12.70 0.5 AZ92A 70 4.0 AZ92A-T6 12.70 0.5 AZ92A 75 2.0 AZ91C-F 12.70 0.5 AZ92A 100 2.5 AZ91C-T4 12.70 0.5 AZ92A 78 4.0 AZ91C-T6 12.70 0.5 AZ92A 75 2.0 AZ81A-F 12.70 0.5 AZ92A 100 2.5 AZ81A-T4 12.70 0.5 AZ92A 85 8.0 EK41A-T5 12.70 0.5 EK41A 100 1.0 EK41A-T6 12.70 0.5 EK41A 93 6.2 EZ33A-T5 12.70 0.5 EZ33A 100 1.1 HK31A-T6 12.70 0.5 HK31A 100 9.5 HK31A-H24 EZ33A 83 1.0 HZ32A-T5 12.70 0.5 HZ32A 93 3.8 HM21A-T8 1.63 0.064 EZ33A 88 1.5 HM31A 74 1.5 15.88 0.625 EZ33A 71 1.8 HM31A HM31A-F 58 2.5 (a) Percentage elongation across the weld over a 50 mm (2 in.) gage length from tension tests Butt and fillet joints are preferred in magnesium because they are the easiest to make by arc welding, and they provide more consistent results than other types of joints Lap joints are used sometimes, but they are generally less satisfactory than butt joints for load-carrying applications Arc welded joints in annealed magnesium alloy sheet and plate have room-temperature tensile strengths less than 10% lower than those of the base metal (joint efficiencies, of greater than 90%) Tensile strengths of arc welds in hard-rolled material, however, are significantly lower than those of the base metal (joint efficiencies of only 60 to 85%) as a result of the annealing effect of welding Consequently, room-temperature strengths of arc welded joints in magnesium alloy sheet and plate are about the same regardless of the temper of the base metal Joint efficiencies also are affected by service temperatures For example, arc welds in HK31A-H24 sheet exhibit joint efficiencies of 75 to 80% at room temperature, but these increase to nearly 100% at 260 °C (500 °F) Joint efficiencies of arc welds in HM21A-T8 sheet range from about 80% at room temperature to 100% at 200 °C (400 °F) HM31-T5 extrusions exhibit joint efficiencies of 75 to 85% from room temperature to about 370 °C (700 °F), and 100% at 425 °C (800 °F) and above There are no appreciable differences in properties between welds made with alternating current and those made with direct current Stress Relieving Arc welds in some magnesium alloys specifically the magnesium-aluminum-zinc series and alloys containing more than 1% Al are subject to stress-corrosion cracking, and thermal treatment must be used to remove the residual stresses that cause this condition This treatment consists of placing the parts in a jig or clamping plate and heating them at the temperatures indicated in Table 22 for the specified times After heating, the parts are cooled in still air The use of jigs is sometimes necessary so that relief of stresses does not result in warpage of the assembly Table 22 Times and temperatures for stress relieving arc welds in magnesium alloys Alloy Temperature Time, °C °F AZ31B-H24(a) 150 300 60 AZ31B-O(a) 260 500 15 260 500 15 Sheet Extrusions(b) AZ31B-F(a) AZ61A-F(a) 260 500 15 AZ80A-F(a) 260 500 15 AZ80A-T5(a) 204 400 60 HM31A-T5 425 800 60 ZK60A-F(c) 260 500 15 ZK60A-T5(c) 150 300 60 AM100A 260 500 60 AZ63A 260 500 60 AZ81A 260 500 60 AZ91C 260 500 60 AZ92A 260 500 60 EZ33A 250 480 600 HZ32A 350 660 120 K1A(e) ZE41A 330 625 120 ZH62A 330 625 120 Castings(d) (a) Postweld stress relief is required to prevent possible stress-corrosion cracking in this alloy Postweld heat treatment of other alloys is used primarily for straightening or for stress relieving prior to machining (b) When extrusions are welded to sheet, distortion may be minimized by using a lower stress-relieving temperature and a longer time For example, 60 at 150 °C (300 °F) instead of 15 at 260 °C (500 °F) (c) ZK60 has limited weldability (d) These stress-relief schedules for casting alloys will not develop maximum joint strength For maximum strength, use the postweld heat treatments shown in Table 23 (e) No stress relief is necessary after welding this alloy The other types of magnesium alloys, including those containing manganese, rare earths, thorium, zinc, or zirconium, are not sensitive to stress corrosion and normally not require stress relief after welding Repaired castings are generally heat treated again after welding All alloys which require full (T6) heat treatment are best welded in the solution-treated (T4) condition After welding, a short solution treatment followed by the normal aging treatment is necessary The postweld heat treatment of magnesium casting alloys depends on the desired final temper of the castings (Table 23) However, if complete solution heat treatment is not desired, welded castings should always be stress relieved as described in Table 22 Table 23 Weld preheat and postweld heat treatment of magnesium castings Alloy Metal temper before welding(a) Desired temper after welding(a) Weld preheat(b) Postweld heat treatment (time after reaching temperature)(c) AZ63A T4 T4 None to 380 °C (720 °F) max(d) h at 390 °C (730 °F)(d) AZ63A T4 or T6 T6 None to 380 °C (720 °F) max(d) h at 390 °C (730 °F)(d) + h at 220 °C (425 °F) AZ63A T5 T5 None to 260 °C (500 °F); 1 h max h at 220 °C (425 °F) at 260 °C (500 °F) AZ81A T4 T4 None to 400 °C (750 °F) max(d) h at 415 °C (780 °F)(d) AZ91C T4 T4 None to 400 °C (750 °F) max(d) h at 415 °C (780 °F)(d) AZ91C T4 or T6 T6 None to 400 °C (750 °F) max(d) h at 415 °C (780 °F)(d) + either h at 215 °C (420 °F) or 16 h at 170 °C (335 °F) AZ92A T4 T4 None to 400 °C (750 °F) max(d) h at 415 °C (780 °F)(d) AZ92A T4 or T6 T6 None to 400 °C (750 °F) max(d) h at 415 °C (780 °F)(d) + either h at 260 °C (500 °F) or h at 220 °C (425 °F) AM100A T6 T6 EK41A T4 or T6 T6 None to 400 °C (750 °F) max(d) None to 260 °C (500 °F); 1 h at 415 °C (780 °F)(d) + h at 220 °C (425 °F) h max 16 h at 205 °C (400 °F) h max 16 h at 205 °C (400 °F) h max h at 215 °C (420 °F) (optional)(e) h at 345 °C (650 °F) + h at 215 °C (420 °F) at 260 °C (500 °F) EK41A T5 T5 None to 260 °C (500 °F); at 260 °C (500 °F) EZ33A F or T5 T5 None to 260 °C (500 °F); at 260 °C (500 °F) HK31A T4 or T6 T6 None to 260 °C (500 °F) 16 h at 205 °C (400 °F) (optional)(e) h at 315 °C (600 °F) + 16 h at 205 °C (400 °F) HZ32A F or T5 T5 None to 260 °C (500 °F) 16 h at 315 °C (600 °F) K1A F F None None ZE41A F or T5 T5 None to 315 °C (600 °F) h at 330 °C (625 °F) (optional)(e) h at 330 °C (625 °F) + 16 h at 175 °C (350 °F) ZH62A F or T5 T5 None to 315 °C (600 °F) 16 h at 250 °C (480 °F) (optional)(e) h at 330 °C (625 °F) + 16 h at 175 °C (350 °F) ZK51A F or T5 T5 None to 315 °C (600 °F) 16 h at 175 °C (350 °F) (optional)(e) h at 330 °C (625 °F) + 16 h at 175 °C (350 °F) ZK61A F or T5 T5 None to 315 °C (600 °F) 48 h at 150 °C (300 °F) ZK61A T4 or T6 T6 None to 315 °C (600 °F) 2-5 h at 500 °C (930 °F)(d) + 48 h at 130 °C (265 °F) (a) Temper T4, solution heat treated; T6, solution heat treated and aged; T5, artificially aged; F, as-cast (b) Heavy and unrestrained sections usually need no preheat; thin and restrained sections may need to be preheated to indicated temperatures to avoid weld cracking (c) Temperatures listed are maximum allowable; furnace controls should be set so that temperature does not cycle above indicated maximum (d) SO2 or CO2 atmosphere recommended when heating temperature exceeds 370 °C (700 °F) (e) Optional postweld heat treatment serves to induce greater stress relief Spot welds in magnesium have good static strength, but their fatigue strength is lower than for either riveted or adhesive-bonded joints Spot-welded assemblies are used mainly for low-stress applications and are not recommended where joints are subject to vibration Typical shear strengths of spot welds in three alloys are given in Table 24 Shear strengths of welds AZ61A and HK31A are about the same as those in AZ31B Table 24 Typical shear strengths of spot welds in magnesium alloys Material thickness, sheet Average spot diameter Single-spot shear strength for AZ31B-O HK31A-H24 mm in mm in kg lb kg lb 0.508 0.020 3.56 0.14 100 220 0.635 0.025 4.06 0.16 120 270 0.813 0.032 4.57 0.18 150 330 135 300 1.016 0.040(a) 5.08 0.20 185 410 170 375 1.270 0.050 5.84 0.23 240 530 250 550 1.600 0.063(b) 6.86 0.27 340 750 325 720 2.032 0.080 7.87 0.31 405 890 2.540 0.100 8.64 0.34 535 1180 3.175 0.125(c) 9.65 0.38 695 1530 675 1490 Material thickness, extrusions Average spot diameter Single-spot shear strength for MIA-F mm in mm in kg lb 0.508 0.020 3.05 0.12 50 105 0.635 0.025 3.56 0.14 70 150 0.813 0.032 4.06 0.16 95 210 1.016 0.040 4.57 0.18 130 285 1.295 0.051 5.33 0.21 175 385 1.626 0.064 6.10 0.24 225 500 2.057 0.081 7.11 0.28 305 670 2.591 0.102 7.87 0.31 400 885 3.175 0.125 8.89 0.35 515 1135 (a) Single-spot shear strength for HM21A-T8 alloy is 165 kg (360 lb) (b) Single-spot shear strength for HM21A-T8 alloy is 300 kg (660 lb) (c) Single-spot shear strength for HM21A-T8 alloy is 555 kg (1220 lb) Recommended spot spacings and edge distances for spot welds are given in Table 25 Where magnesium sheets of unequal thickness are to be spot welded, the thickness ratio should not exceed to Table 25 Recommended spot spacing and edge distance for spot welds in magnesium alloy sheet Sheet thickness Spot spacing Edge distance Minimum Nominal Minimum Nominal mm in mm in mm in mm in mm in 0.508 0.020 6.35 0.25 12.70 0.50 3.81 0.15 6.35 0.25 0.635 0.025 6.35 0.25 12.70 0.50 4.06 0.16 6.35 0.25 0.813 0.032 7.87 0.31 15.75 0.62 4.57 0.18 6.35 0.25 1.015 0.040 9.65 0.38 19.05 0.75 5.08 0.20 6.35 0.25 1.296 0.051 10.41 0.41 19.05 0.75 5.84 0.23 7.87 0.31 1.626 0.064 12.70 0.50 25.40 1.00 6.85 0.27 9.65 0.38 2.057 0.081 15.75 0.62 31.75 1.25 7.87 0.31 10.41 0.41 2.591 0.102 15.75 0.62 31.75 1.25 9.40 0.37 12.70 0.50 3.175 0.125 19.05 0.75 38.10 1.50 11.18 0.44 15.75 0.62 Seam welds of the continuous or intermittent types have strength properties comparable to those of spot welds Shear strengths of about 19.2 to 40.2 kg/linear mm (1075 to 2250 lb/linear in.) of welded seam can be obtained in AZ31B sheet from to mm (0.040 to 0.12 in.) thick The cost of weldments is less likely to vary significantly with quantity than the cost of other methods of fabrication Therefore, weldments are used most often where quantities are small or where fabrication of specific designs is impractical or impossible by other methods For a dozen parts of the design shown in Fig 16, sand castings cost twice as much as weldments; at about 35 pieces, the tooling cost for casting was absorbed, and casting was more economical for larger lots Fig 16 Effect of quantity on the cost of magnesium alloy sand castings compared with the same parts made as weldments For the electronic mounting base shown in Fig 17, the die casting was superior to the weldment in mechanical properties, although properties of both were above minimum requirements Die castings were less expensive than weldments in quantities of 5000 (including cost of tooling); in quantities of 100, weldments were less expensive Fig 17 Comparison of a magnesium alloy electronic mounting base as manufactured by welding and by casting Weight of part, 1.25 kg (2.75 lb) Adhesive bonding of magnesium has become an important fabrication technique The fatigue characteristics of adhesive-bonded lap joints are better than those of other types of joints The probability of stress concentration failure in adhesive-bonded joints is minimal Adhesive bonding permits the use of thinner materials than can be effectively riveted The adhesive fills the spaces between the contacting surfaces and thus acts as an insulator between any dissimilar metals in the joint It also permits manufacture of assemblies having surfaces smoother than those associated with riveting Adhesive bonding has been limited almost exclusively to lap joints A few general factors should be considered when designing adhesive-bonded joints: • • • • • • Joint strengths vary with the lap width, metal thickness, direction in which loads are applied, and type of adhesive used The joint should be designed so that it provides a sufficiently large bonded area The adhesive layer should be uniform in thickness The adhesive layer should be as thin as possible, yet applied in sufficient quantity so that no joints are starved Joints should be designed so that pressure and heat can be readily applied The curing temperatures of the common structural adhesives are below the temperatures at which the properties of hard-rolled magnesium sheet are affected, and thus they not significantly reduce the properties of magnesium alloys in the annealed (O) condition The effect of lap width on the shear strength of joints bonded with phenolic rubber-base resin adhesive is shown in Fig 18(a) The effect of temperature on the shear strength of adhesive-bonded joints in magnesium and aluminum is shown in Fig 18(b) Fig 18 Effect of (a) lap width and (b) temperature on the shear strength of joints bonded with a phenolic rubber-base resin adhesive The characteristics and properties of some adhesives used with magnesium are given in Table 26 These adhesives cannot be utilized in assemblies operating above 80 °C (180 °F) because of low shear strength Table 26 Characteristics of adhesives used for bonding magnesium These adhesives are for service at temperatures up to 82 °C (180 °F) General type of composition Curing conditions Temperature °C °F Adhesive thickness Time, Shear strength mm MPa Pressure MPa ksi in ksi Phenol formaldehyde plus polyvinyl formal powder(a) 132 270 32 0.34-3.44 0.05-0.5 0.00.152 0.00.006 11-18 1.62.6 Phenolic rubber-base resin(a) 163 325 20 1.38 0.2 0.0760.152 0.0030.006 15-18 2.22.6 Phenolic synthetic rubber base plus thermosetting resin 177 350 10 0.0480.310 0.0070.045 0.1270.508 0.0050.020 7-17 1.02.5 60 0.689 0.1 0.1270.508 0.0050.020 14-20 2.12.9 Ethoxyline resin liquid, powder, or stick used like solder 199 390 60 Contact Contact 0.0250.152 0.0010.006 10-15 1.52.2 Ethoxyline resin (two liquids) Room Room 24 h Contact Contact 0.0250.152 0.0010.006 Epoxy-type resin paste plus liquid activator 93 200 60 Contact Contact 0.0760.127 0.0030.005 21 max 3.0 max Rubber base 204 400 1.38 0.2 0.2540.381 0.0100.015 12-16 1.72.3 Vinyl phenolic 149 300 preheat 1.38 0.2 0.1020.305 0.0040.012 7-12 1.01.7 135204 275400 70-4 93 200 45 Contact Contact 0.2540.762 0.0100.030 8-12 1.21.8 93 200 45 0.096 0.014 (tape) (tape) 10-12 1.41.7 149 300 15 0.193 0.028 0.0510.102 0.0020.004 17 max 2.4 max Epoxy-type resin Phenolic (a) Known to meet USAF specifications Riveting Essentially the same procedures employed in riveting other materials are used in riveting magnesium alloys Standard procedures are used for drilling and countersinking holes Both dimpling and machine countersinking are used in flush riveting With machine countersinking, it is desirable to have a cylindrical land with a minimum depth of 0.38 mm (0.015 in.) at the bottom of the hole Thus, machine countersinking is limited to sheet thick enough to permit lands of this depth with a given size of rivet Dimpling of magnesium alloy sheet is a hot-forming operation; to prevent reduction of properties during dimpling, the sheet must not be heated to excessively high temperatures or for long periods Only aluminum rivets should be used if galvanic incompatibility is to be minimized, and those up to mm ( in.) in 16 diameter can be driven cold The ease of driving rivets of alloy 5056 will vary with the temper Quarter-hard temper (5056-H32) is satisfactory for all normal riveting Machinability Magnesium and its alloys can be machined at extremely high speeds using greater depths of cut and higher rates of feed than can be used in machining other structural metals There are no significant differences in machinability among magnesium alloys Therefore, a specific magnesium alloy rarely, if ever, is selected in place of another magnesium alloy solely on the basis of machinability Because of the free-cutting characteristic of magnesium, chips produced in machining are well broken Dimensional tolerances of about ±0.1 mm ( a few thousandths of an inch) can be obtained using standard operations The power required to remove a given amount of metal is lower for magnesium than for any other commonly machined metal Based on the volume of metal removed per minute, the comparative power requirements of various metals are: Metal Relative power Magnesium alloys 1.0 Aluminum alloys 1.8 Brass 2.3 Cast iron 3.5 Tool wear is also reduced when machining magnesium because of the high thermal conductivity of the metal, which allows rapid dissipation of heat, and the low cutting pressures required Ordinary carbon steel tools can be used in machining magnesium, but high-speed tools and carbide-tipped tools can be used for high production rate jobs An outstanding machining characteristic of magnesium alloys is their ability to acquire an extremely fine finish Often, it is unnecessary to grind and polish magnesium to obtain a smooth finished surface Surface smoothness readings of about 0.1 μm (3 to μin.) have been reported for machined magnesium and are attainable at both high and low speeds, with or without cutting fluids Cutting Fluids (Coolants) In the machining of magnesium alloys, cutting fluids provide far smaller reductions in friction than they provide in the machining of other metals; thus, they are of little use in improving surface finish and tool life Most machining of magnesium alloys is done dry, but cutting fluids sometimes are used for cooling the work Although less heat is generated during machining of magnesium alloys than during machining of other metals, higher cutting speeds and the low heat capacity and relatively high thermal expansion characteristics of magnesium may make it Nickel alloys 10.0 necessary to dissipate the small amount of heat that is generated Heat generation can be minimized by the use of correct tooling and machining techniques, but cutting fluids are sometimes needed to reduce the possibilities of distortion of the work and ignition of fine chips Because they are used primarily to dissipate heat, cutting fluids are referred to as coolants when used in the machining of magnesium alloys Low-carbon steel 6.3 Numerous mineral oil cutting fluids of relatively low viscosity are satisfactory for use as coolants in the machining of magnesium Suitable coolants represent a compromise between cooling power and flash point Additives designed to increase wetting power are usually beneficial Only mineral oils should be used as coolants; animal and vegetable oils are not recommended Water-soluble oils, oil-water emulsions, or water solutions of any kind should not be used on magnesium Water reduces the scrap value of magnesium turnings and introduces potential fire hazards during shipment and storage of machine shop scrap Safe Practice The possibility of chips or turnings catching fire must be considered when magnesium is to be machined Chips must be heated close to their melting point before ignition can occur Roughing cuts and medium finishing cuts produce chips too large to be readily ignited during machining Fine finishing cuts, however, produce fine chips that can be ignited by a spark Stopping the feed and letting the tool dwell before disengagement, and letting the tool or tool holder rub on the work, produce extremely fine chips and should be avoided Factors that increase the probability of chip ignition are: • • • • • Extremely fine feeds Dull or chipped tools Improperly designed tools Improper machining techniques Sparks caused by tools hitting iron or steel inserts Feeds less than 0.02 mm (0.001 in.) per revolution and cutting speeds higher than m/s (1000 ft/min) increase the risk of fire Even under the most adverse conditions with dull tools and fine feeds chip fires are very unlikely at cutting speeds below 3.5 m/s (700 ft/min) Any fire hazard connected with machining of magnesium is easy to control, and large quantities of magnesium are machined without difficulty Following these rules will reduce the fire hazard: • • • • • Keep all cutting tools sharp and ground with adequate relief and clearance angles Use heavy feeds to produce thick chips Use mineral oil coolants (15 to 19 L/min, or to gal/min) whenever possible; when not possible, avoid fine cuts Do not allow chips to accumulate on machines or on the clothing of operators Remove dust and chips at frequent intervals and store in clean, plainly labeled, covered metal cans Keep an adequate supply of a recommended magnesium fire extinguisher within reach of operators If dry chips are ignited, they will burn with a brilliant white light, but the fire will not flare up unless disturbed Burning chips should be extinguished as follows: • • • Scatter a generous layer of clean, dry cast iron chips or metal extinguishing powder over the burning magnesium Cover actively burning fires on combustible surfaces like wood floors with a layer of the extinguishant, then shovel the entire mass into an iron container or onto a piece of iron plate Do not use water or any of the common liquid or foam-type extinguishers, which intensify magnesium chip fires Distortion of magnesium parts during machining occurs rarely and usually can be attributed to excessive heating or improper chucking or clamping Heating of the work is increased by use of dull or improperly designed tools, extremely high machining feeds and speeds, or very fine cuts Because magnesium has a relatively high coefficient of thermal expansion, such excessive heating results in substantial increases in dimensions particularly in thin sections, where heating causes relatively large increases in temperature Use of sharp, properly designed tools; mineral oil coolants; and relatively coarse feeds and depths of cut reduces excessive heating Wide variations in room temperature during machining can also cause sufficient dimensional change to affect machining tolerances Clamping should always be done on heavier sections of magnesium castings, and clamping pressures should not be high enough to cause distortion Special care should be taken with light parts that could be distorted easily by the chuck or by use of heavy cuts Distortion of magnesium parts is seldom caused by stresses during casting, forging, or extruding, but it may result from stresses caused by straightening or welding Such stresses can be relieved prior to machining by heating at 260 °C (500 ... 7 .60 103 15.0 75 12.0 480 70 76 56. 0 8.00 110 16. 0 84 62 9.0 425 62 31 23.0 7 .60 83 12.0 84 17.0 69 10.0 590 86 51.5 38.0 8.00 90 13.0 92 15.0 14.0 62 9.0 395 57 (b) (b) 7 .60 (b) (b) 80 16. 5 16. 0... Max 68 .5 rem Min 71.5 Max 68 .5 rem 1.0 Min rem 2.0 Max 62 .5 rem 16. 5 Min rem 19.5 Max 62 .5 rem 1.0 16. 5 Min rem 2.0 19.5 Max 87.5 rem 9.5 Min 90.5 CT-1000 65 .5 CNZP-18 16 65 .5... 2.99 99 .64 0.24 0.03 99 .62 0. 26 99. 36 99.25 90 10 Hall flow rate, s/50 g Compacted properties Green density, g/cm3 Tyler sieve analysis, % 165 MPa (12 tsi) 6. 30 g/cm3 6. 04 6. 15 (890)