24 July 2021 Gear Steel Bar
40MnBH Gear Steel Bar
40MnB gear steel is a new type of steel that has successfully replaced 40Cr steel. It has high strength, hardness, wear resistance and good toughness. Its hardenability is slightly higher than that of 40Cr, and its critical quench hardened in oil. 18～33mm; good machinability after normalizing, cold drawing, rolling, tapping and forging, heat treatment process performance are also good, grain growth at high temperature, oxidation, decarburization tendency and quenching deformation tendency are small, there is temper brittleness, tempering stability is slightly worse than 40Cr steel.
It can be used as a steering arm, steering knuckle, steering shaft, semi-axle, worm, spline shaft, brake adjustment arm, etc. on the car, and can also replace 40Cr steel to make larger-section parts. This type of steel is used for the manufacture of mechanical parts that can withstand medium- and medium-speed work, such as the knuckles and rear axles of automobiles, gears, shafts, worms, spline shafts, and top sleeves on machine tools; After tempering at medium temperature, it is used to manufacture parts that are subjected to high loads, impacts, and medium speeds, such as gears, spindles, oil pump rotors, sliders, and collars. After quenching and low-temperature tempering, they are used to manufacture heavy loads and low loads. Parts with impact and wear resistance, solid thickness below 25mm in section, such as worm, spindle, shaft, collar, etc.; after quenched and tempered and high frequency surface quenched, used for manufacturing with high surface hardness and wear resistance. Parts without major impact, such as gears, sleeves, shafts, spindles, crankshafts, spindles, pins, connecting rods, screws, nuts, intake valves, etc. In addition, this type of steel is suitable for the manufacture of various transmission parts for carbonitriding treatment, such as gears and shafts with larger diameters and low temperature toughness.
Chemical Composition:
C(％) | Si(％) | Mn(％) | P(％) | S(％) | Cr(％) | B(%) | Ti(%) | Other(%) |
|---|---|---|---|---|---|---|---|---|
0.37-0.44 | 0.17-0.37 | 1.00-1.40 | 0.035 | 0.035 | Max 0.35 | 0.0005-0.0035 | — | — |
Mechanical properties:
Yield Strength Rp0.2(MPa) | Tensile Strength Rm(MPa) | Impact KV (J) | Elongation A (%) | Reduction in cross section on fracture Z (%) | Impact toughness value αkv (J / cm2) | Hardness |
|---|---|---|---|---|---|---|
≥ 871 | ≥ 785 | 41 | 44 | 43 | ≥69 (7) | ≤ 207HB |
Physical properties:
Property | Density kg/dm3 | Temperature T °C/F | Specific heat J / kgK | Thermal conductivity W/mK | Electric resistance µΩ·cm |
|---|---|---|---|---|---|
558 (≥) | 581 (≥) | 43 | 32 | 22 | Solution and Aging, Annealing, Ausaging, Q+T,etc |
Temp. °C/°F | Creep strain limit (10000h) (Rp1,0) N/mm2 | Creep rupture strength (10000h) (Rp1,0) N/mm2 | - | - | - |
339 | 425 | 698 | - | - | - |
Heat treatment and microstructure specifications:
Heat treatment specifications: normalizing, 880 ~ 900 ℃, air cooling; quenching, 850 ± 20 ℃, oil cooling; tempering, 510 ± 30 ℃, water-cooled.
Delivery Status:
Delivery by rolling or forging. According to the demand side can also heat treatment (normalizing, annealing or high temperature tempering) state delivery.