7075-T6 vs. 7075-T62: Understanding the Key Differences in Aerospace Alloys

7075 T6 and 7075-T62 aluminum alloys both belong to the 7000 series of aluminum alloys and are commonly used in aerospace, military, and high-strength structural applications. Their main difference lies in the different heat treatment processes, although their alloy compositions are very similar.

7075-T6 is more suitable for applications requiring high tensile strength and yield strength, making it ideal for high-strength structural components, but it has relatively poor toughness and fatigue strength.
7075-T62 is better suited for applications subjected to repeated stress and requiring higher fatigue strength, offering better wear resistance, but sacrifices some strength and ductility.

Comparison Table of 7075-T6 and 7075-T62 Aluminum Alloys

Properties	7075-T6	7075-T62
Alloy Composition	Contains zinc (Zn), magnesium (Mg), copper (Cu), etc.	Contains zinc (Zn), magnesium (Mg), copper (Cu), etc.
Heat Treatment	Solution heat treatment + artificial aging	Solution heat treatment + long-time aging
Tensile Strength	Higher (better than T62)	Slightly lower than T6
Yield Strength	High	Slightly lower than T6
Brinell Hardness	Relatively low	Slightly higher than T6
Elongation at Fracture	Relatively high (better ductility)	Slightly lower than T6
Fatigue Strength	Relatively low	Relatively high
Corrosion Resistance	Good, better than 2000 series, but not as good as 5000 series	Good, better than 2000 series, but not as good as 5000 series
Ductility	Relatively good	Worse (compared to T6)
Toughness	Relatively low (more brittle at low temperatures)	Slightly better (better toughness than T6)
Applications	Aerospace, aircraft structures, high-stress structural components	Aerospace, components subjected to repeated loads, wear-resistant applications
Main Advantages	High tensile strength and yield strength, good toughness and ductility	Higher fatigue strength and hardness, excellent wear resistance
Main Disadvantages	Poor fracture toughness, prone to embrittlement, relatively low fatigue strength	Lower strength, poor ductility and toughness

7075 T6 Aluminum and 7075-T62 Aluminum Mechanical Properties

Property	7075-T6 Aluminum	7075-T62 Aluminum
Brinell Hardness	150	160
Elastic (Young's, Tensile) Modulus (GPa)	70	70
Elongation at Break (%)	7.9	7.2
Fatigue Strength (MPa)	160	170
Poisson's Ratio	0.32	0.32
Shear Modulus (GPa)	26	26
Shear Strength (MPa)	330	330
Tensile Strength: Ultimate (UTS, MPa)	560	560
Tensile Strength: Yield (Proof, MPa)	480	460

Tensile Strength: The tensile strength of 7075-T6 is slightly higher than that of 7075-T62, particularly in terms of yield strength, where T6 is slightly superior. T6 alloys are suitable for applications requiring higher strength.
Brinell Hardness: The hardness of 7075-T62 is slightly higher than 7075-T6, indicating that T62 has a more wear-resistant surface. This characteristic makes 7075-T62 potentially more advantageous in applications requiring wear resistance.
Elongation at Fracture: 7075-T6 has slightly higher elongation at fracture, meaning it will have more ductility under extreme loads and can withstand more deformation before breaking.
Fatigue Strength: 7075-T62 has slightly higher fatigue strength than 7075-T6, meaning T62 maintains its performance under repeated stress for a longer time, making it suitable for structural components subjected to repeated loading.

7075 T6 Aluminum vs. 7075-T62 Aluminum Heat Treatment Process

7075 T6: In the T6 condition, 7075 aluminum alloy undergoes solution heat treatment (where the material is heated to a specific temperature to dissolve the alloying elements) followed by artificial aging (cooling and reheating the alloy to a lower temperature to enhance its hardness and strength).
7075 T62: The T62 condition is slightly different from T6, usually involving a longer aging time during the process to adjust its microstructure for optimized fatigue strength and ductility. This variation results in 7075-T62 having slightly higher hardness than T6 but lower toughness.

7075 T6 vs. 7075-T62 Corrosion Resistance

The corrosion resistance of 7075 aluminum alloy is generally better than that of 2000 series alloys but not as good as 3000 or 5000 series alloys. This is due to its higher zinc content, which provides good corrosion resistance, although in certain corrosive environments (such as marine environments), it may face some challenges.

7075 T6 vs. 7075-T62 Ductility and Toughness

7075-T6 has good ductility, but its toughness is slightly inferior to other aluminum alloys (like 6061), especially at very low temperatures. While its strength and fatigue performance are high, it may not be suitable for extreme environments due to its brittleness.

7075-T62 has better ductility than T6, with superior elongation at fracture, making it suitable for structures that require larger deformation or are used under repeated loads.

7075 T6 vs. 7075-T62 Applications

7075-T6 is the most common material used in aerospace and military applications, widely used for aircraft bodies, wing spars, airframe structures, aircraft engine components, and high-stress structures. Its high strength and adequate ductility make it outstanding for structural components.
7075-T62, with its higher fatigue strength and hardness, is more suitable for applications subjected to repeated loading or requiring wear resistance, such as aerospace components and mechanical structures that need high fatigue resistance.

7075-T6: If a project focuses primarily on tensile strength and higher yield strength, T6 may be the more appropriate choice. It is suitable for high-load applications requiring strength and toughness, but its fracture toughness may not be as high as other aluminum alloys.

7075-T62: If the design requires higher fatigue strength and surface hardness, with slightly less emphasis on ductility, T62 may be more suitable. Its advantage lies in performance under long-term repeated loading and better wear resistance.