주요 특징
- 7075-T73 is a overaged temper of 7075 aluminum that sacrifices some strength for significantly improved stress-corrosion cracking (SCC) resistance.
- T73 typically achieves 85–90% of T6’s tensile strength while delivering far better corrosion performance in harsh environments.
- It is the preferred temper for aerospace structural components exposed to corrosive conditions where long-term reliability is critical.
- Available in plate, bar, sheet, and tube forms conforming to ASTM B209 and B211 standards.
- Good machinability — similar to T6 — but welding is not recommended; mechanical fastening is preferred.
소개
7075-T73 aluminum is a heat-treated temper of the 7075 alloy series, engineered for applications where stress-corrosion cracking (SCC) resistance matters as much as strength. While 7075-T6 delivers maximum strength, the T73 temper trades roughly 10–15% of that strength for a dramatic improvement in corrosion resistance and fracture toughness. This makes T73 the specified temper for aerospace structural parts that operate in corrosive environments over long service lives.
Understanding 7075-T73 Aluminum
7075 is a 7000-series wrought aluminum alloy with zinc as the primary alloying element, supplemented by magnesium and copper. The T73 temper is achieved through a two-stage artificial aging process: first a higher-temperature aging step, then a lower-temperature stabilization. This overaging treatment precipitates the alloying elements more uniformly, reducing the electrochemical driving force for stress-corrosion cracking.
The key distinction: T6 maximizes strength but is susceptible to SCC in certain orientations and environments. T73 accepts a modest strength reduction to deliver reliable long-term performance in corrosive conditions.
Chemical Composition of 7075-T73 Aluminum
| 요소 | 구성 (%) |
|---|---|
| 알루미늄(Al) | Remainder (87.1–91.4) |
| 아연(Zn) | 5.1 - 6.1 |
| 마그네슘(Mg) | 2.1 - 2.9 |
| 구리(Cu) | 1.2 - 1.8 |
| 크롬(Cr) | 0.18 - 0.28 |
| 실리콘(Si) | ≤ 0.40 |
| 철(Fe) | ≤ 0.50 |
| 망간(Mn) | ≤ 0.30 |
| 티타늄(Ti) | ≤ 0.20 |
The composition is identical to other 7075 tempers — the difference lies entirely in the heat treatment, not the chemistry. Zinc provides the primary strengthening, while copper improves strength but reduces corrosion resistance. The T73 temper mitigates this copper-related corrosion susceptibility through its controlled precipitation structure.
Mechanical Properties of 7075-T73 Aluminum
| 속성 | 7075-T73 | 7075-T6 (for comparison) |
|---|---|---|
| 인장 강도(MPa) | 505 | 572 |
| 항복 강도(MPa) | 435 | 503 |
| 전단 강도(MPa) | 290 | 331 |
| 연신율 (%) | 13 | 11 |
| 경도(브리넬) | 135 | 150 |
| 골절 인성 | 더 높음 | Lower |
| SCC Resistance | 우수 | Poor |
T73 retains approximately 85–90% of T6’s tensile strength while significantly improving fracture toughness and stress-corrosion cracking resistance. The slightly higher elongation also means T73 is less brittle than T6, offering better damage tolerance.
T73 vs T6: When to Choose Each
Choosing between T73 and T6 depends on your application’s priorities:
- Choose T6 when maximum strength is the priority and the environment is controlled (dry, indoor, or short-term exposure).
- Choose T73 when the component will be exposed to corrosive environments, cyclic loading, or long service lives where SCC is a concern. This is why aerospace structural specifications frequently call for T73 over T6.
For a broader comparison of 7075 against other alloys, see our 7050 vs 7075 guide or our 6061 vs 7075 comparison.
Applications of 7075-T73 Aluminum
The aerospace industry is the primary user of 7075-T73. Typical applications include:
- Aircraft wing spars and fuselage structural components
- Landing gear parts exposed to environmental conditions
- Helicopter rotor components
- Military equipment and vehicle armor
Beyond aerospace, T73 is used in high-performance sporting goods (bicycle frames, climbing gear), precision mold tooling, and automotive components where both strength and corrosion resistance are required. 7075-T73 aluminum sheet 그리고 round bar are the most commonly specified forms.
Machining and Working with 7075-T73
7075-T73 machines well, similar to T6. Use carbide tooling with appropriate cutting fluids to manage heat. Sharp tools and optimized feeds prevent built-up edge and surface defects.
Welding is not recommended for 7075-T73, as with all 7075 tempers. The heat-affected zone will lose strength and become susceptible to cracking. Mechanical fastening — riveting or bolting — is the standard joining method. For more on this topic, see our 7075 welding guide.
Common forms and standards:
| 양식 | ASTM 표준 |
|---|---|
| Bar, Rod | ASTM B211 |
| Plate, Sheet | ASTM B209 |
| 튜브 | ASTM B210 / B241 |
결론
7075-T73 aluminum occupies a specific niche: it trades a modest amount of strength compared to T6 for dramatically better stress-corrosion cracking resistance and fracture toughness. For aerospace structural components and other applications exposed to corrosive environments over long service lives, T73 is often the mandatory choice — not because it’s stronger, but because it’s more reliable under real-world conditions.
Linsy Aluminum supplies 7075-T73 in plate, sheet, bar, and tube forms, with customization for dimensions and surface finishes. Typical lead times are 10–60 days depending on temper, dimensions, and processing requirements. Contact Linsy Aluminum to discuss your 7075-T73 specifications.
자주 묻는 질문
How does 7075-T73 differ from 7075-T6?
T73 has lower tensile strength (505 MPa vs 572 MPa for T6) but significantly better stress-corrosion cracking resistance and fracture toughness. T73 is specified when long-term reliability in corrosive environments matters more than peak strength. T6 is preferred when maximum strength is needed in controlled environments.
What industries primarily use 7075-T73 aluminum?
Aerospace is the largest consumer — aircraft structural parts, wing spars, fuselage components, and landing gear. It is also used in military equipment, high-performance sporting goods, and precision mold tooling where both strength and corrosion resistance are required.
Can 7075-T73 aluminum be welded?
Welding 7075-T73 is not recommended. The heat-affected zone loses strength and becomes susceptible to cracking. Riveting, bolting, or adhesive bonding are the standard joining methods. Friction stir welding is the only welding process that may be considered, but it requires specialized equipment.
What forms are available for 7075-T73 aluminum?
7075-T73 is available in plate (ASTM B209), bar and rod (ASTM B211), sheet (ASTM B209), and tube (ASTM B210/B241). Common thicknesses for plate range from 6 mm to 100 mm+. For specific forms like 7075 flat bar 또는 square tube, check product availability.
Is 7075-T73 stronger than 6061-T6?
Yes. Even with the strength reduction from the T73 temper, 7075-T73 (505 MPa tensile) is still significantly stronger than 6061-T6 (310 MPa tensile). The trade-off is cost, weldability, and corrosion resistance — 6061 is cheaper, easier to weld, and resists corrosion better.
