AZ31B is a wrought magnesium-base alloy in the Section 4.2 Magnesium-Wrought Alloys group, containing aluminum and zinc as the principal alloying elements.
AZ31B is a wrought magnesium-base alloy containing aluminum and zinc. It is available in the form of sheet, plate, extruded sections, forgings, and tubes. AZ31B has good room-temperature strength and ductility and is used primarily for applications where the temperature does not exceed 300°F. Increased strength is obtained in the sheet and plate form by strain hardening with a subsequent partial anneal (H24 and H26 temper). No treatments are available for increasing the strength of this alloy after fabrication.
Forming of AZ31B must be done at elevated temperatures if small radii or deep draws are required. If the temperatures used are too high or the times too great, H24 and H26 temper material will be softened. This alloy is readily welded but must be stress relieved after welding to prevent stress corrosion cracking.
Material specifications covering AZ31B wrought products are given in Table 4.2.1.0(a). Room-temperature mechanical and physical properties are shown in Tables 4.2.1.0(b) through (d). The effect of temperature on physical properties is shown in Figure 4.2.1.0.
| Specification | Form |
|---|---|
| AMS 4375 | Sheet and plate |
| AMS 4376 | Plate |
| AMS 4377 | Sheet and plate |
| ASTM B 107 | Extrusion |
| ASTM B 91 | Forging |
The temper index for AZ31B is as follows:
| Section | Temper |
|---|---|
| 4.2.1.1 | O |
| 4.2.1.2 | H24 |
| 4.2.1.3 | H26 |
| 4.2.1.4 | F |
Tables 4.2.1.0(b) through (d) — design mechanical and physical properties of AZ31B sheet, plate, extrusion, and forging by temper and thickness — pending digitization (dense multi-column property tables; MIL-HDBK-5J pp. 4-7–4-9).
Figure 4.2.1.0. Effect of temperature on the physical properties of AZ31B.
Effect of temperature on the tensile modulus of sheet and plate is presented in Figure 4.2.1.1.4. Typical room-temperature stress-strain and tangent-modulus curves are presented in Figure 4.2.1.1.6.
Figure 4.2.1.1.4. Effect of temperature on the tensile modulus (E) of AZ31B-O sheet and plate.
Figure 4.2.1.1.6. Typical tensile and compressive stress-strain and compressive tangent-modulus curves for AZ31B-O sheet and plate at room temperature.
Effect of temperature on the mechanical properties of sheet and plate is shown in Figures 4.2.1.2.1 through 4.2.1.2.4, and 4.2.1.2.6. Typical room-temperature tension and compression stress-strain and tangent-modulus curves for sheet are shown in Figure 4.2.1.2.6.
Figure 4.2.1.2.1. Effect of temperature on the tensile ultimate strength (Ftu) and the tensile yield strength (Fty) of AZ31B-H24 sheet and plate.
Figure 4.2.1.2.2. Effect of temperature on the compressive yield strength (Fcy) and the shear ultimate strength (Fsu) of AZ31B-H24 sheet and plate.
Figure 4.2.1.2.3. Effect of temperature on the bearing ultimate strength (Fbru) and the bearing yield strength (Fbry) of AZ31B-H24 sheet and plate.
Figure 4.2.1.2.4. Effect of temperature on the tensile modulus (E) of AZ31B-H24 sheet and plate.
Figure 4.2.1.2.6. Typical tensile and compressive stress-strain and compressive tangent-modulus curves for AZ31B-H24 sheet at room temperature.
MIL-HDBK-5J provides no additional narrative for the H26 temper beyond the design property table referenced in Section 4.2.1.0; see Table 4.2.1.0(c) (AZ31B plate, H26 temper).
Figures 4.2.1.4.8(a) and (b) contain fatigue data for forged disk at room temperature.
Figure 4.2.1.4.8(a). Best-fit S/N curves for unnotched AZ31B-F magnesium alloy forged disk, transverse direction. Product form: forged disk, 1 inch thick (TUS = 38 ksi, TYS = 26 ksi, room temperature); unnotched specimen, 0.75-inch gross diameter, 0.30-inch net diameter; axial loading, 1500 cpm, air environment; sample size 194. Reference 4.2.1.1.8.
Figure 4.2.1.4.8(b). Best-fit S/N curves for notched, Kt = 3.3, AZ31B-F magnesium alloy forged disk, transverse direction. Product form: forged disk, 1 inch thick (TUS = 38 ksi, TYS = 26 ksi, room temperature); notched specimen, Kt = 3.3, 0.350-inch gross diameter, 0.280-inch net diameter, 0.010-inch root radius, 60° flank angle; axial loading, 1500 cpm, air environment; sample size 34. Reference 4.2.1.1.8.
AZ61A is a wrought magnesium-base alloy containing aluminum and zinc. It is available in the form of extruded sections, tubes, and forgings in the as-fabricated (F) temper. AZ61A is much like AZ31B in general characteristics. The increased aluminum content increases the strength and decreases the ductility slightly.
Severe forming must be done at elevated temperatures. This alloy is readily welded but must be stress relieved after welding to prevent stress corrosion cracking.
Material specifications covering AZ61A are given in Table 4.2.2.0(a). Room-temperature mechanical and physical properties are shown in Table 4.2.2.0(b).
| Specification | Form |
|---|---|
| AMS 4350 | Extrusion |
| ASTM B 91 | Forging |
Table 4.2.2.0(b) — Design Mechanical and Physical Properties of AZ61A Magnesium Alloy Extrusion and Forging — pending digitization (dense multi-column property table; MIL-HDBK-5J p. 4-18).
ZK60A is a wrought magnesium-base alloy containing zinc and zirconium. It is available as extruded sections, tubes, and forgings. Increased strength is obtained by artificial aging (T5) from the as-fabricated (F) temper. ZK60A has the best combination of high room-temperature strength and ductility of the wrought magnesium-base alloys. It is used primarily at temperatures below 300°F.
ZK60A has good ductility as compared with other high-strength magnesium alloys and can be formed or bent cold into shapes not possible with those alloys having less ductility. It is not considered a weldable alloy.
Material specifications for ZK60A are given in Table 4.2.3.0(a). Room-temperature mechanical and physical properties are shown in Tables 4.2.3.0(b) and (c). Elevated temperature curves for physical properties are shown in Figure 4.2.3.0.
| Specification | Form |
|---|---|
| ASTM B 107 | Extrusion |
| AMS 4352 | Extrusion |
| AMS 4362 | Die and hand forgings |
The temper index for ZK60A is as follows:
| Section | Temper |
|---|---|
| 4.2.3.1 | F |
| 4.2.3.2 | T5 |
Table 4.2.3.0(b) — Design Mechanical and Physical Properties of ZK60A Magnesium Alloy Extrusion (ASTM B 107) — pending digitization (dense multi-column property table; MIL-HDBK-5J p. 4-20).
Table 4.2.3.0(c) — Design Mechanical and Physical Properties of ZK60A Magnesium Alloy Extrusion and Forging (AMS 4352 / AMS 4362, T5 temper) — pending digitization (dense multi-column property table; MIL-HDBK-5J p. 4-21).
Figure 4.2.3.0. Effect of temperature on the physical properties of ZK60A magnesium alloy.
MIL-HDBK-5J provides no additional narrative or figures for the F temper beyond the design property table referenced in Section 4.2.3.0; see Table 4.2.3.0(b) (ZK60A extrusion, F temper).
Typical room-temperature tension and compression stress-strain curves for extrusions are shown in Figures 4.2.3.2.6(a) and (b). Fatigue curves are presented in Figures 4.2.3.2.8(a) through (c).
Figure 4.2.3.2.6(a). Typical tensile stress-strain curve for ZK60A-T5 extrusion at room temperature. Ramberg-Osgood n (RT) = 7.0.
Figure 4.2.3.2.6(b). Typical compressive stress-strain curve for ZK60A-T5 extrusion at room temperature.
Figure 4.2.3.2.8(a). Best-fit S/N curves for unnotched ZK60A-T5 extruded bar, longitudinal direction. Product form: extruded bar, 0.50-inch diameter (TUS = 47.5 ksi, TYS = 40.9 ksi, room temperature, unnotched); unnotched specimen, 0.500-inch gross diameter, 0.400-inch net diameter, 0.750-inch root diameter, 7.500 inches long; axial loading, 3600 cpm, room temperature, air environment; sample size 21. Reference 4.2.3.2.8.
Figure 4.2.3.2.8(b). Best-fit S/N curves for notched, Kt = 2.4, ZK60A-T5 extruded bar, longitudinal direction. Product form: extruded bar, 0.50-inch diameter (TUS = 63.7 ksi, TYS = 40.9 ksi, room temperature, notched); circumferentially notched specimen, Kt = 2.4, 0.500-inch gross diameter, 0.400-inch net diameter, 0.032-inch notch radius, 60° flank angle; axial loading, 3600 cpm, room temperature, air environment; sample size 30. Reference 4.2.3.2.8.
Figure 4.2.3.2.8(c). Best-fit S/N curves for notched, Kt = 3.4, ZK60A-T5 extruded bar, longitudinal direction. Product form: extruded bar, 0.50-inch diameter (TUS = 58.2 ksi, TYS = 40.9 ksi, room temperature, notched); circumferentially notched specimen, Kt = 3.4, 0.500-inch gross diameter, 0.400-inch net diameter, 0.010-inch notch radius, 60° flank angle; axial loading, 3600 cpm, room temperature, air environment; sample size 36. Reference 4.2.3.2.8.