Brand: 38CrMoALA
Standard: GB/T 3077- 1988
● Features and scope of use
It has high surface hardness, wear resistance and fatigue strength, good heat resistance and corrosion resistance, and low hardenability. Used to manufacture nitrided parts, which have high wear resistance, high fatigue strength, considerable strength and high dimensional accuracy after treatment, such as copying dies, cylinder liners, gears, high-pressure valves, boring bars, worms, grinding machine spindles, etc. However, larger parts are not suitable.
38crmoal is a kind of high-grade nitrided steel, which is mainly used for nitrided parts with high wear resistance, high fatigue strength and considerable strength, or nitrided parts with high wear resistance with small impact load, such as boring bars, grinding machine spindles, automatic lathe spindles, worms, precision screws, precision gears, high-pressure valves, valve stems, gauges, templates, rollers, copying dies, cylinders, compressor piston rods, steam turbines, etc.
chemical composition
C: 0.35 ~ 0.42
Silicon Si: 0.20-0.45
Manganese Mn: 0.30-0.60
Sulfur S: allowable residual content ≤0.035.
Phosphorus P: allowable residual content ≤0.035.
Chromium Cr: 1.35 ~ 1.65
Al: 0.70 ~ 1. 10
Nickel Ni: allowable residual content ≤0.030.
Copper and copper: allowable residue ≤0.030.
Mo: 0. 15 ~ 0.25
mechanical character
● Mechanical properties:
Tensile strength σ b (MPa): ≥ 980 (100)
Yield strength σ s (MPa): ≥ 835 (85)
Elongation δ 5 (%): ≥ 14
Area shrinkage ψ(%):50
Impact work akv (j): ≥ 7 1
Impact toughness value α kV (j/cm2): ≥ 88 (9)
Hardness: ≤229HB
Sample size: the blank size of the sample is 30mm.
Heat treatment specification
● Heat treatment specification and metallographic structure:
Heat treatment specification: 940℃ quenching, water cooling and oil cooling; Tempering at 640℃, water cooling and oil cooling.
● Delivery status: The goods are delivered in heat-treated (normalizing, annealing or high-temperature tempering) or non-heat-treated state, and the delivery status shall be indicated in the contract.
Use of 38CrMoAlA
38CrMoAlA alloy steel is a special steel with seawater corrosion resistance.
1.38CrMoAlA alloy steel material is mainly used for manufacturing pipelines and equipment. It has the advantages of strong corrosion resistance and convenient installation.
Second, the reasons for corrosion resistance:
Al (aluminum) in (1)38CrMoAlA alloy steel can react with O (oxygen) in the air to form Al2O3 (aluminum trioxide), thus forming a protective film, which is both corrosion-resistant and corrosion-resistant.
(2) (2) Cr (Cr), Mo (Mo) and ions in 38crmoala alloy steel can automatically replenish the gap formed by pitting corrosion of steel by Cl (Cl) ions in seawater, and form a dense protective layer to prevent pitting corrosion from developing in depth. So as to resist corrosion and prolong the service life.
Third, welding.
38CrMoAlA seamless steel pipe has good weldability and special corrosion-resistant covered electrode "HaiO3", so there is no special welding requirement.
Fourth, application examples
38CrMoAlA seamless steel pipe material is the most ideal pipeline and processing material for transporting water, oil, gas and seawater-containing media in coastal power plants, coastal oil fields, coastal natural gas and petrochemical plants.
What's the difference between 38CrMoAlA and 42CrMo models?
38CrMoAlA is a special nitrided steel, which is generally only used for nitrided parts requiring high surface wear resistance. Usually, the surface hardness after nitriding is above 920HV, and the pretreatment is tempering (usually, the quenching and tempering hardness is required to be ≥260HB, such as 262~302HB). The nitriding speed of 38CrMoAl is faster, and the depth of nitrided layer can be deeper, but the brittleness of nitrided layer is relatively large, which is not suitable for making parts subjected to great impact. Aluminum-containing nitride steel (Cr-Mo-V nitride steel is recommended) is generally not recommended for important heavy-duty gears abroad.
42CrMo has high strength and hardenability, good toughness, small deformation during quenching, and high high temperature creep strength and endurance strength. It can be used to manufacture forgings with higher strength and larger quenched and tempered section than 35CrMo steel, such as locomotive traction gear, supercharger transmission gear, rear axle, connecting rod under heavy load, spring clip, etc., and can also be used for drill pipe joints and fishing tools in deep wells below 2000 m. ..
Comparison of Chinese and foreign brands
China GB/T3077: 38CrMoAlA
International standard ISO: 4 1CrAlMo74
The former Soviet Union гост: 38X2MA (38XMA)
American ASTM:-
United Nations USA:-
Japan JIS: SACM645
German DIN: 4 1CrAlMo7 34CrAlMo5
British BS: 905M39 905M3 1
French franc: 40 Canadian dollars