42CrMo steel vs 42CrMo4 steel

42CrMo grade is from China GB/T 3077 standard steel material. It is a medium carbon alloy structural steel with good mechanical properties, good hardenability and wide application. In the machinery industry, 42CrMo alloy is often used to manufacture gears, connecting rods, high strength bolts and other important parts. China factory create 42CrMo follow SAE 4140 steel standard.
42CrMo4 grade is from European standard-EN10083. It is a kind of alloy steel with high hardenability, good toughness and small deformation during quenching. 42CrMo4 steel has high creep strength and endurance strength at high temperature.
 

The comparison of 42CrMo steel and 42CrMo4 steel composition

Grades	C	Si	Mn	S	P	Mo	Cr	Ni
42CrMo	0.38-0.45	0.17-0.45	0.5-0.8	≤0.04	≤0.035	0.15-0.25	0.90-1.20	0
42CrMo4	0.38-0.45	≤0.40	0.6-0.9	≤0.035	≤0.035	0.15-0.30	0.90-1.20	≤0.40

 
In GB3077, 42CrMo alloy steel is usually delivered in hot rolling or forging. If the buyer requires delivery in heat treatment (annealing, normalizing or high temperature tempering), it needs to be specified in the contract.
 
EN10083 standard specifies the relevant requirements of hardenability. When 42CrMo4 steel is selected as gear workpiece, it is convenient to choose this standard for ordering.

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