R9M4K8 (EP688)

Steel has an increased tendency to decarburize, lower viscosity, increased wear resistance, reduced grindability.

For the manufacture of tools used in the processing of high-strength stainless and heat-resistant steels, alloys and improved alloyed steels under conditions of increased heating of the cutting edge (gear-cutting tools, cutters, shaped cutters, countersinks, taps). for processing high-strength stainless and heat-resistant steels and alloys under conditions of increased heating of the cutting edge: gear-cutting tools, mills, shaped cutters, countersinks, taps.

Classification

Country	Section	Category
Country	Section	Category
CIS, Russia, Ukraine	Tool steel	High speed tool steel

Chemical composition

Standard	Fe, %	Si, %	Mn, %	Co, %	Cr, %	Cu, %	Ni, %	V, %	P, %	C, %	S, %	Mo, %	W, %
Standard	Fe, %	Si, %	Mn, %	Co, %	Cr, %	Cu, %	Ni, %	V, %	P, %	C, %	S, %	Mo, %	W, %
GOST 19265-73	68.39–72.59	0.2–0.5	0.2–0.5	7.5–8.5	3–3.6	< 0.25	< 0.6	2.3–2.7	< 0.03	1–1.1	< 0.03	3.8–4.3	8.5–9.5

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Physical characteristics

Temperature, °C	$E\cdot 10^{9}$ , $MPa$	$\varkappa$ , $\frac{W}{m\cdot K}$	$\rho$ , $\frac{kg}{m^3}$
Temperature, °C	$E\cdot 10^{9}$ , $MPa$	$\varkappa$ , $\frac{W}{m\cdot K}$	$\rho$ , $\frac{kg}{m^3}$
20	2.29		8930
100		25
200		27
300		28
400		29
500		30
600		31
700		32
900		32

Mechanical properties at 20 °C

Rolling	Standard	Size, mm	Tension	Classifiers	$\sigma _{U}$ , $MPa$	$\sigma_{P}$ , $MPa$	$\psi$ , %	$KCU\cdot 10^{3}$ , $\frac{J}{m^2}$	d5, %	Treatment
Rolling	Standard	Size, mm	Tension	Classifiers	$\sigma _{U}$ , $MPa$	$\sigma_{P}$ , $MPa$	$\psi$ , %	$KCU\cdot 10^{3}$ , $\frac{J}{m^2}$	d5, %	Treatment
Alloy	GOST 19265-73			annealing	960	540	10	80	7	delivery condition

Brinell hardness number

Rolling	Standard	Classifiers	Value, HBW
Rolling	Standard	Classifiers	Value, HBW
Alloy	GOST 19265-73	annealing	285

Critical point temperatures

Ac₁, K	Ac₃(Ac_m), K	Ar₃(Arc_m), K	Ar₁, K
Ac₁, K	Ac₃(Ac_m), K	Ar₃(Arc_m), K	Ar₁, K
800	840	790	750

Analogues

USA	Germany
USA	Germany
T11348	S10-4-3-10

Standards

Standard	Description
Standard	Description
GOST 19265-73

Description of chemical elements

Element	Units of measurement	Description
Element	Units of measurement	Description
Fe	%	Iron
Si	%	Silicon
Mn	%	Manganese
Co	%	Cobalt
Cr	%	Chrome
Cu	%	Copper
Ni	%	Nickel
V	%	Vanadium
P	%	Phosphorus
C	%	Carbon
S	%	Sulfur
Mo	%	Molybdenum
W	%	Tungsten

Description of physical characteristics

Parameter	Units of measurement	Description
Parameter	Units of measurement	Description
$E\cdot 10^{9}$	$MPa$	Elastic modulus
$\varkappa$	$\frac{W}{m\cdot K}$	Coefficient of thermal conductivity (the heat capacity of the material)
$\rho$	$\frac{kg}{m^3}$	The density of the material

Description of mechanical properties

Parameter	Units of measurement	Description
Parameter	Units of measurement	Description
d5	%	Elongation at break
$\sigma _{U}$	$MPa$	Ultimate tensile strength
$\sigma_{P}$	$MPa$	Proportionality limit
$\psi$	%	Reduction in cross section on fracture
$KCU\cdot 10^{3}$	$\frac{J}{m^2}$	Impact toughness

Description of temperatures of critical points

Parameter	Units of measurement	Description
Parameter	Units of measurement	Description
Ac₁	K
Ac₃(Ac_m)	K
Ar₃(Arc_m)	K
Ar₁	K