42CrMo hot rolled steel sheet/bar

42CrMo4 is a steel for quenching and tempering, which has a good combination of strength and toughness in the quenched and tempered condition. After the oil quenching, the steel will be through hardened up to ø60 mm bar diameter. The microstructure of larger dimensions is not fully martensite. The steel is applicable to induction hardening. The surface hardness will exceed min. 53 HRC. 42CrMo4 can be delivered M-treated in order to optimize the machinability.

Chemical Composition
Steel Grade	C	Si	Mn	P	S	Cr	Mo	Cu
35CrMo	0.38～0.45%	0.17～0.37%	0.50～0.80%	≤0.035%	≤0.035%	0.90～1.20%	0.15～0.25%	≤0.30%

Mechanical properties
 

Yield strength σs/MPa (>=)	Tensile strength σb/MPa (>=)	Elongation δ5/% (>=)	Reduction of area ψ/% (>=)	Impact absorbing energy Aku2/J (>=)	Hardness HBS 100/3000 max
≥930(95)	≥1080(110)	≥12	≥45	≥78(8)	≤217HB

In order to increase the die life to more than 800,000 die times, the pre-hardened steel can be hardened by quenching and low temperature tempering. When quenching, preheat at 500-600℃ for 2-4 hours, and then keep it at 850-880℃ for a certain period of time (at least 2 hours), then put it in oil and cool to 50-100℃ and air cooling, the hardness can reach 50 after quenching -52HRC, in order to prevent cracking, 200℃ low temperature tempering treatment should be carried out immediately. After tempering, the hardness can be maintained above 48HRC.
 

42CrMo Steel Heat Treatment

Annealing

Annealing in 760±10℃, furnace cooling to 400℃ then air cooling.

Normalizing

Normalizing in 760±10℃, air cooling after out of the furnace.

Notes About Quenching and Tempering Treatment

Must pay attention to the temperature of liquid coolant. And must make sure there are no oil contamination or other impurities. Otherwise, the hardness of steel will be not enough or out of the balance.

Quenching and tempering for billet steel material without processing, then it will get non-uniform hardness. So processing of forging or grinding is necessary before the Q+T.