40MnB, alloy structural steel.

  Unified digital code: A71402

Standard: GB / T 3077-1988
     Outline
     Feature
High strength, hardness, wear resistance and good toughness, is an alternative to the more successful new 40Cr steel steel. Modulation of carbon steel, cold heading die steel. The steel price is moderate, easily processed, after appropriate heat treatment after the availability of a certain toughness, ductility and wear resistance. Normalizing the ball of the organization can promote and improve the hardness of less than 160HBS rough cutting. Temperature of 550 ~ 570 ℃ in the tempering, the steel has the best mechanical properties. Hardenability of the steel is higher than 45 steel, suitable for high-frequency hardening, flame hardening and other surface hardening treatment.

 40MnB steel use
Used cars on the steering arm, steering knuckle, steering shaft, axle, worm, spline shaft, brake adjustment arm, but also a larger cross-section instead of 40Cr steel parts. This steel quenched after for the manufacture of medium load and medium speed to withstand the mechanical parts work, such as automotive steering knuckle, on the machine after the axle and gear, shaft, worm, spline shaft, the top cover, etc.; by quenching and medium-temperature tempering for the manufacture of high load, the impact of work and medium speed parts such as gears, shaft, oil pump rotor, slide, rings, etc.; after quenching and tempering for the manufacture of heavy duty, low impact and wear resistance, cross-sectional thickness of 25mm on the following physical components, such as worm, spindle shaft, ring, etc.; after quenching and after quenching for the manufacture of high-frequency surface has a high surface hardness and wear resistance no significant impact on the parts such as gears, sleeves, shafts, spindles, crankshafts, spindles, pins, connecting rods, screws, nuts, intake valve and so on. In addition, the manufacture of steel and suitable for carbonitriding treatment of a variety of transmission parts, such as large diameter and low-temperature toughness, good gear and shaft.

This steel is generally used in the quenched state, temperature range -20 ~ 425 ℃, the main place of 40Cr steel production, a small section of the quenched parts, such as automotive axle, steering shaft, worm, spline shaft and spindle , gear, etc. They can also replace the 40Cr steel production Φ250 ~ 320mm hoist a large section of the intermediate shaft and other parts. When the production of smaller parts can be replaced when the steel 40CrNi steel use.

   Physical properties
   Chemical composition
Carbon C: 0.37 ~ 0.44

Si Si: 0.17 ~ 0.37

  Manganese Mn: 1.10 ~ 1.40

Sulfur S: to allow the residual content of ≤ 0.35

  Phosphorus P: allow the residual content of ≤ 0.35

Chromium Cr: allow the residual content of ≤ 0.30

Ni: to allow the residual content of ≤ 0.30

  Copper Cu: to allow the residual content of ≤ 0.30

Boron B: 0.0005 ~ 0.0035
    Mechanical properties
Blank sample size (mm): 25

Heat treatment:

  The first quenching temperature (℃): 850; Coolant: Oil

Second quenching temperature (℃): -

Tempering heating temperature (℃): 500; coolant: water, oil

Tensile strength σb (MPa): ≥ 980 (100)

Yield strength σs (MPa): ≥ 785 (80)

Elongation δ5 (%): ≥ 10

Reduction of area ψ (%): ≥ 45

Impact energy Akv (J): ≥ 47

Impact toughness αkv (J/cm2): ≥ 59 (6)

Brinell hardness (HBS100/3000) (annealing or tempering condition): ≦ 207

[Main features]

This is an alternative to 40Cr steel, the more successful of the new steel, which has high strength, hardness, wear resistance and good toughness, its hardenability slightly higher than the 40Cr in the critical oil quenching diameter of 18 ~ 33mm; normalizing good after cutting, cold drawing, rolling, tapping, and forging, heat treatment process performance are good, high temperatures, grain growth, oxidation, decarburization orientation and deformation hardening tendencies are small; but have temper brittleness, tempering somewhat less stable than the 40Cr steel.

[Application Examples]