31CrMoV9/1.8519

31CrMoV9 is a nitriding steel which has at least 2.3%Cr,0.15%Mo,0.1%V as strengthening alloy elements. Due to its high wear resistance,it is mainly used in the automotive industry and general components mechanical engineering.30CrMoV9 is difficult to weld and therefore should not be used in weld constructions.It can attain surface hardness of 800 HV after nitriding.

Chemical Composition

Grade	C	Mn	P	S	Si	V	Cr	Mo
31CrMoV9/1.8519	0.27-0.34	0.40-0.70	≤ 0.025	≤ 0.035	≤ 0.4	0.1-0.2	2.3-2.7	0.15-0.25

Mechanical Properties

Diameter d mm	16-40	40-100	100-160	160-250
Yield Strength Mpa	≥900	≥800	≥700	≥650
Tensile Strength Mpa	1100-1300	1000-1200	900-1100	850-1050
Elongation, %	≥9	≥10	≥11	≥12
impact，J	≥25	≥30	≥35	≥40
Hardness,HB	331-380	298-359	271-331	253-319

Forging

Heat the temperature between 1050℃-1150℃,hold suitable time for the steel to be thoroughly heated.Reheat the steel once temperature  below 850°C. Crack is easily occured when improper cooling way after forged,so it  should be cooled as slowly as possible in the furnace or in sand after forged.

Heat Treatment

Heat Treatment Process	Temperature Range	Holding Time	Cooling Method	Maximum Hardness
Soft Annealing	Heat to 650-720℃	N/A	Cool slowly in furnace	248 HB
Hardening	Harden from 870-930℃	N/A	Oil/Polymer or Water Quenching	N/A
Tempering	Tempering temperature: 580-700℃	N/A	Air Cooling	N/A
Nitriding	Gas/Plasma Nitriding Temperature: 570-580℃ (Gas, Salt Bath) <br> Gas/Plasma Nitriding Temperature: 580℃ (Powder, Plasma)	N/A	N/A	Surface Hardness after Nitriding: 800 HV

Application

31CrMoV9 nitriding steel is used in mechanics automotive and general mechanics, which must be nitrided for very high wear forces, for example, gears, rods or axes.Structural parts of medium and large cross sections and high surface hardness, e.g., valve and gate valves, cylinders for combustion engines, superheated steam valves and fittings.