Steel 74 (M74)

Designation

Name	The value
Designation GOST Cyrillic	74
Designation GOST Latin	74
Transliteration	74
By chemical elements	74

Name	The value
Designation GOST Cyrillic	М74
Designation GOST Latin	M74
Transliteration	M74
By chemical elements	Mo74

Description

74 steel is used: for the manufacture of railway rails P50.

Note

M74 — steel open-hearth rail.
Allowed production of rails P50 of the oxygen-Converter steel when you stop the purge of iron in the carbon content not less than 0.60%. Thus in the designation of steel grades the letter «M» is replaced by letter «K» — К74.

Standards

Name	Code	Standards
Rails. Lining. Lining. Crutches	В42	GOST 7174-75, GOST 18267-82, GOST 24182-80

Chemical composition

Standard	C	S	P	Mn	Si	Fe
GOST 24182-80	0.69-0.8	≤0.045	≤0.035	0.75-1.05	0.18-0.4	Rest

Fe is the basis.
In rails made of Kerch ores, the content of phosphorus is not more than 0.040%, sulfur is not more than 0.050%, arsenic is not more than 0.15%.
The rails of Group II must be made of calm open-hearth steel, deoxidized with aluminum or manganese-aluminum alloy.

Mechanical properties

Section, mm	s_T\|s_0,2, MPa	σ_U, MPa	d₅, %	y, %	KCU, kJ/m²	HB, MPa
The mechanical properties of rails type R50 GOST 18267-82. Bulk quenching in oil + Furnace vacation
	≥794	≥1176	≥6	≥25	≥245	341-388
Mechanical properties of steel for rails type R50 GOST 24182-80 on delivery
	-	≥860	≥5	-	-	-

Description mechanical marks

Name	Description
s_T\|s_0,2	Yield strength or limit of proportionality with a tolerance for residual deformation of 0.2%
σ_U	Limit short-term strength
d₅	Elongation after rupture
y	The relative narrowing
KCU	Toughness
HB	Brinell hardness number