1.2738/40CrMnNiMo8-6-4

TOOL STEEL FOR PLASTIC MOULDING AND EXTRUSION

NORM: ISO 4957

APPLICATION:

Steel susceptible to dies for forming plastic products, large injection moulds, large plastic moulds highly stressed in the core and pressure products, deeply machined tools etc.

MECHANICAL PROPERTIES:

Hardness after	Tempering ºC	Symbol	Value
Soft annealing	–	HB	≤235
Toughening		HB	300
Quenching with 860 ºC in oil	–	HRC	52
Quenching with 860 ºC in oil and tempering (cooling during quenching can be performed gradually in the salt bath at 180–220 ºC and then cooled in the air)	200	HRC	51
	300	HRC	48.5
	400	HRC	46
	450	HRC	44
	500	HRC	42
	550	HRC	38.5
	600	HRC	33

PHYSICAL PROPERTIES:

Property	Unit	Value
Density, ρ	g*cm-3	7.85
Thermal expansion, α20-100ºC)	K-1	12.2*10-6
Thermal conductivity, λ20ºC)	W*m-1*K-1	36

Technological treatment processes:

Technological treatment processes			Possible application	Temperature, °C
Hot forming	Forging		+	1050-850
	Rolling		+	1050-850
Treatment	Heat treatment	Quenching	+	840-870
		Tempering	+	500-650
	Precipitation strengthening	Supersaturation	–	–
		Ageing	–	–
	Annealing	Soft annealing	+	710-740
		Stress relieving	+	600-700
Thermochemical treatment	Nitriding		+	470-540
	Other		–	–

INTERNATIONAL STEEL GRADES: