40Cr alloy structural steel
Shanghai Lijia Special Steel Co.
According to the standard GB/T 3077-1999
Characteristics: Medium-carbon modulating steel, cold heading die steel. The steel price is moderate, easy to process, after appropriate heat treatment can obtain a certain toughness, plasticity and wear resistance. Normalization can promote the organization of spheroidization, improve the hardness less than 160HBS blank cutting performance. Tempered at a temperature of 550 ~ 570 ℃, the steel has the best overall mechanical properties. The hardenability of the steel is higher than 45 steel, suitable for high-frequency quenching, flame quenching and other surface hardening treatment, etc..
Chemical composition (mass fraction, %)
Carbon C ?0.37~0.44
Silicon Si ?0.17~0.37
Manganese Mn ?0.50~0.80
Chromium Cr ?0.80~1.10
Nickel Ni ? ≤0.30.
Mechanical Properties:
Sample blank size (mm): 25
Heat Treatment:
First Quenching Heating Temperature (℃): 850; Coolant: Oil
Second Quenching Heating Temperature (℃): -
Tempering Heating Temperature (℃): 520; Coolant: Water, Oil
Tensile Strength（σb/MPa）:≧980
Yield Point（σs/MPa）:≧785
Extensibility after Breaking（δ5/%）:≧9
Sectional Shrinkage（ψ/%）:≧45
Impact Absorption Function（Aku2/J）:≧47
Brinell Hardness（HBS100/ 3000) (annealed or high-temperature tempered state):≦207
Critical point temperature (approximate value): Acm=780℃
Normalizing specification: Temperature 850~870℃, hardness 179~229HBS.
Cold-pressed blanks softening treatment specification
Temperature 740~760℃, holding time 4~6h, and then at a rate of 5 ~10 ℃ / h of the cold rate, cooling down to ≤ 600 ℃, out of the air-cooled.
Hardness before treatment ≤ 217HBS, after softening hardness ≤ 163HBS.
Tempering treatment specification
Quenching temperature 850 ℃ ± 10 ℃, oil cooling; tempering temperature 520 ℃ ± 10 ℃, water and oil air-cooled.
Use:
This steel is used to manufacture medium load and medium speed mechanical parts after tempering, such as automobile steering knuckles, rear half shafts, and machine tools on the gears, shafts, worm gears, spline shafts, top bushings, etc.; quenched and tempered at medium temperatures for the manufacture of high loads, impacts, and medium-speed parts, such as gears, spindles, pump rotors, sliders, rings, etc.; quenched and low tempered used to manufacture high loads, impact and medium speed parts, such as gears, rotor, sliding block, ring etc.; after quenching and low-temperature tempering for the manufacture of heavy loads, low impact and wear resistance, cross-section of the entity thickness of 25mm or less parts, such as worm gears, spindles, shafts, rings, etc.; tempered and high-frequency surface quenching is used for the manufacture of high surface hardness and abrasion resistance without a great deal of impact on the parts, such as gears, bushings, axles, shafts, crankshafts, arbors, pins, connecting rods, screws, nuts, intake valves, etc.. Valves, etc. In addition, this steel is suitable for the manufacture of carbon nitrogen **** infiltration treatment of a variety of transmission parts, such as gears and shafts with large diameter and good low-temperature toughness.
Supply state and hardness
Annealed state, hardness ≤ 207HBS.
Modulus of elasticity: modulus of elasticity E (20 ℃) /MPa 200000 ~ 211700, the shear modulus G (20 ℃) 80800