The strength and hardness of aluminum alloys vary significantly depending on the alloy grade (such as 6061, 7075, 2024, etc.) and heat treatment state (such as T4, T6, T651, etc.). The following is an explanation from the specific grade, performance data, pressure bearing capacity and application scenarios:
I. Comparison of strength and hardness of common aluminum alloy grades
1. 6 series aluminum alloy (taking 6061-T6 as an example)
Strength:
Tensile strength: ≥290 MPa (equivalent to about 29 kg force per square millimeter).
Yield strength: ≥240 MPa (critical stress at which the material begins to produce permanent deformation).
Hardness:
Brinell hardness (HB): ≥95 (equivalent to the indentation hardness measured with a 10mm steel ball and a load of 3000kg).
Features: Balanced comprehensive performance, corrosion resistance, easy processing, commonly used in bicycle frames, skis, and mechanical parts.
2. 7 series aluminum alloy (taking 7075-T6 as an example)
Strength:
Tensile strength: ≥572 MPa (close to the strength level of ordinary steel).
Yield strength: ≥503 MPa.
Hardness:
Brinell hardness (HB): ≥150 (hardness close to medium carbon steel).
Features: high strength and high hardness, commonly known as "aircraft-grade aluminum alloy", used for aircraft structural parts, high-end molds, and racing car parts.
3. 2 series aluminum alloy (taking 2024-T3 as an example)
Strength:
Tensile strength: ≥470 MPa.
Yield strength: ≥325 MPa.
Hardness:
Brinell hardness (HB): ≥120.
Features: Strength is second only to 7 series, with good toughness, used for aviation skins and high-strength bolts.
4. 5 series aluminum alloy (taking 5052-H32 as an example)
Strength:
Tensile strength: ≥215 MPa.
Yield strength: ≥145 MPa.
Hardness:
Brinell hardness (HB): ≥60.
Features: Excellent corrosion resistance, medium strength, used for ship decks, pressure vessels, and automobile fuel tanks.
II. Pressure bearing capacity: How to quantify?
The "pressure bearing capacity" of aluminum alloys needs to be comprehensively evaluated in combination with material strength, structural design, and stress form (such as compression, tension, and shear):
1. Compressive strength (uniform compression scenario)
Formula reference:
Compressive strength ≈ yield strength × safety factor (the safety factor in engineering is usually 1.5-3.0).
Case:
The yield strength of 7075-T6 aluminum alloy is 503 MPa. If the safety factor is 2.0, the allowable compressive strength is 251.5 MPa (equivalent to about 2515 tons of pressure per square meter).
In practical applications, such as aircraft landing gear, structural optimization (such as hollow tubular design) is required to improve compressive stability.
2. Tensile strength (tensile scenario)
Directly corresponding indicators: tensile strength is the maximum stress before the material is broken.
The tensile strength of 6061-T6 is 290 MPa, which can be understood as an aluminum rod with a diameter of 10mm can withstand a tensile force of about 22.7 kilonewtons (about 2.3 tons).
3. Shear strength (shear force scenario)
Empirical formula: shear strength ≈ tensile strength × 0.6-0.8 (slightly different for different alloys).
The tensile strength of 2024-T3 aluminum alloy is 470 MPa, and the shear strength is about 282-376 MPa.
III. Key factors affecting strength and hardness
1. Alloying elements and heat treatment
Solid solution + aging treatment: For example, after 6061 aluminum alloy is treated with T6 (solid solution + artificial aging), the strength is increased by about 50% compared with the untreated state (O state).
Typical element effects:
Zinc (7 series): forms strengthening phase AlZnMgCu, significantly improving strength.
Copper (2 series): forms Al₂Cu phase, enhancing hardness and heat resistance.
2. Processing technology
Extrusion molding: For example, the 6063 aluminum alloy profile refines the grains through extrusion, and the strength is increased by 20%-30% compared with the casting state.
Cold work hardening: For example, after cold deformation (H32 state) of 5052 aluminum alloy, the yield strength is increased by about 50% compared with the annealing state (O state).
3. Environmental factors
Temperature: The strength of aluminum alloy decreases significantly at high temperature (for example, the tensile strength of 6061-T6 at 200℃ drops to 60% of room temperature).
Corrosion: After the surface oxide film is damaged, the strength may be reduced due to corrosion pits (need to be protected by processes such as anodizing).
IV. Strength design cases in application scenarios
1. Automobile wheel hub (6061-T6 aluminum alloy)
Design requirements: It needs to withstand vehicle weight, road impact and centrifugal force, tensile strength needs to be ≥260 MPa, and fatigue life needs to be ≥1 million cycles.
Structural optimization: Spoke-type lightweight design is adopted, and finite element analysis (FEA) is used to ensure uniform stress distribution.
2. Aircraft engine bracket (7075-T651 aluminum alloy)
Extreme working conditions: Withstand high temperature (≤120℃) and vibration load, yield strength needs to be ≥480 MPa, and fracture toughness test (such as KIC value ≥24 MPa・√m) needs to be passed.
3. Building curtain wall profile (6063-T5 aluminum alloy)
Load calculation: It needs to withstand wind pressure (such as 5000 Pa) and dead weight, and the allowable stress is 1/1.8 of the yield strength (160 MPa) = 89 MPa to ensure safety redundancy.
V. How to choose a suitable aluminum alloy?
Sort by strength requirements:
Low strength (<200 MPa): 5 series (5052), 3 series (3003) → corrosion-resistant scenarios (such as containers and pipes).
Medium strength (200-400 MPa): 6 series (6061/6063) → structural parts (such as doors and windows, industrial frames).
High strength (>400 MPa): 2 series (2024), 7 series (7075) → aerospace, high-load machinery.
Combined with processability:
For scenarios that require welding, choose 5 series (aluminum-magnesium alloy) or 6 series (good weldability), and avoid 2 series and 7 series (containing copper and zinc, easy to crack during welding).
Summary
The strength and hardness of aluminum alloys can be adjusted in a wide range through alloy design and process control, from "soft as a can" (pure aluminum) to "strong as steel" (7075-T6). The actual pressure bearing capacity needs to be comprehensively evaluated in combination with the brand, status and structural design. It is recommended to ensure safety through mechanical tests (such as tensile tests, compression tests) or reference to industry standards (such as ASTM, GB/T) in engineering.
The strength and hardness of aluminum alloys vary significantly depending on the alloy grade (such as 6061, 7075, 2024, etc.) and heat treatment state (such as T4, T6, T651, etc.). The following is an explanation from the specific grade, performance data, pressure bearing capacity and application scenarios:
I. Comparison of strength and hardness of common aluminum alloy grades
1. 6 series aluminum alloy (taking 6061-T6 as an example)
Strength:
Tensile strength: ≥290 MPa (equivalent to about 29 kg force per square millimeter).
Yield strength: ≥240 MPa (critical stress at which the material begins to produce permanent deformation).
Hardness:
Brinell hardness (HB): ≥95 (equivalent to the indentation hardness measured with a 10mm steel ball and a load of 3000kg).
Features: Balanced comprehensive performance, corrosion resistance, easy processing, commonly used in bicycle frames, skis, and mechanical parts.
2. 7 series aluminum alloy (taking 7075-T6 as an example)
Strength:
Tensile strength: ≥572 MPa (close to the strength level of ordinary steel).
Yield strength: ≥503 MPa.
Hardness:
Brinell hardness (HB): ≥150 (hardness close to medium carbon steel).
Features: high strength and high hardness, commonly known as "aircraft-grade aluminum alloy", used for aircraft structural parts, high-end molds, and racing car parts.
3. 2 series aluminum alloy (taking 2024-T3 as an example)
Strength:
Tensile strength: ≥470 MPa.
Yield strength: ≥325 MPa.
Hardness:
Brinell hardness (HB): ≥120.
Features: Strength is second only to 7 series, with good toughness, used for aviation skins and high-strength bolts.
4. 5 series aluminum alloy (taking 5052-H32 as an example)
Strength:
Tensile strength: ≥215 MPa.
Yield strength: ≥145 MPa.
Hardness:
Brinell hardness (HB): ≥60.
Features: Excellent corrosion resistance, medium strength, used for ship decks, pressure vessels, and automobile fuel tanks.
II. Pressure bearing capacity: How to quantify?
The "pressure bearing capacity" of aluminum alloys needs to be comprehensively evaluated in combination with material strength, structural design, and stress form (such as compression, tension, and shear):
1. Compressive strength (uniform compression scenario)
Formula reference:
Compressive strength ≈ yield strength × safety factor (the safety factor in engineering is usually 1.5-3.0).
Case:
The yield strength of 7075-T6 aluminum alloy is 503 MPa. If the safety factor is 2.0, the allowable compressive strength is 251.5 MPa (equivalent to about 2515 tons of pressure per square meter).
In practical applications, such as aircraft landing gear, structural optimization (such as hollow tubular design) is required to improve compressive stability.
2. Tensile strength (tensile scenario)
Directly corresponding indicators: tensile strength is the maximum stress before the material is broken.
The tensile strength of 6061-T6 is 290 MPa, which can be understood as an aluminum rod with a diameter of 10mm can withstand a tensile force of about 22.7 kilonewtons (about 2.3 tons).
3. Shear strength (shear force scenario)
Empirical formula: shear strength ≈ tensile strength × 0.6-0.8 (slightly different for different alloys).
The tensile strength of 2024-T3 aluminum alloy is 470 MPa, and the shear strength is about 282-376 MPa.
III. Key factors affecting strength and hardness
1. Alloying elements and heat treatment
Solid solution + aging treatment: For example, after 6061 aluminum alloy is treated with T6 (solid solution + artificial aging), the strength is increased by about 50% compared with the untreated state (O state).
Typical element effects:
Zinc (7 series): forms strengthening phase AlZnMgCu, significantly improving strength.
Copper (2 series): forms Al₂Cu phase, enhancing hardness and heat resistance.
2. Processing technology
Extrusion molding: For example, the 6063 aluminum alloy profile refines the grains through extrusion, and the strength is increased by 20%-30% compared with the casting state.
Cold work hardening: For example, after cold deformation (H32 state) of 5052 aluminum alloy, the yield strength is increased by about 50% compared with the annealing state (O state).
3. Environmental factors
Temperature: The strength of aluminum alloy decreases significantly at high temperature (for example, the tensile strength of 6061-T6 at 200℃ drops to 60% of room temperature).
Corrosion: After the surface oxide film is damaged, the strength may be reduced due to corrosion pits (need to be protected by processes such as anodizing).
IV. Strength design cases in application scenarios
1. Automobile wheel hub (6061-T6 aluminum alloy)
Design requirements: It needs to withstand vehicle weight, road impact and centrifugal force, tensile strength needs to be ≥260 MPa, and fatigue life needs to be ≥1 million cycles.
Structural optimization: Spoke-type lightweight design is adopted, and finite element analysis (FEA) is used to ensure uniform stress distribution.
2. Aircraft engine bracket (7075-T651 aluminum alloy)
Extreme working conditions: Withstand high temperature (≤120℃) and vibration load, yield strength needs to be ≥480 MPa, and fracture toughness test (such as KIC value ≥24 MPa・√m) needs to be passed.
3. Building curtain wall profile (6063-T5 aluminum alloy)
Load calculation: It needs to withstand wind pressure (such as 5000 Pa) and dead weight, and the allowable stress is 1/1.8 of the yield strength (160 MPa) = 89 MPa to ensure safety redundancy.
V. How to choose a suitable aluminum alloy?
Sort by strength requirements:
Low strength (<200 MPa): 5 series (5052), 3 series (3003) → corrosion-resistant scenarios (such as containers and pipes).
Medium strength (200-400 MPa): 6 series (6061/6063) → structural parts (such as doors and windows, industrial frames).
High strength (>400 MPa): 2 series (2024), 7 series (7075) → aerospace, high-load machinery.
Combined with processability:
For scenarios that require welding, choose 5 series (aluminum-magnesium alloy) or 6 series (good weldability), and avoid 2 series and 7 series (containing copper and zinc, easy to crack during welding).
Summary
The strength and hardness of aluminum alloys can be adjusted in a wide range through alloy design and process control, from "soft as a can" (pure aluminum) to "strong as steel" (7075-T6). The actual pressure bearing capacity needs to be comprehensively evaluated in combination with the brand, status and structural design. It is recommended to ensure safety through mechanical tests (such as tensile tests, compression tests) or reference to industry standards (such as ASTM, GB/T) in engineering.
