Steel 28Х3СНМВФА (СП28; ЭП326А)

Designation

Name	The value
Designation GOST Cyrillic	28Х3СНМВФА
Designation GOST Latin	28X3CHMBFA
Transliteration	28H3SNMVFA
By chemical elements	28Cr3СНMoWV

Name	The value
Designation GOST Cyrillic	СП28
Designation GOST Latin	CP28
Transliteration	SP28
By chemical elements	СP28

Name	The value
Designation GOST Cyrillic	ЭП326А
Designation GOST Latin	EP326A
Transliteration	EhP326A
By chemical elements	-

Description

28Х3СНМВФА steel is used: for the manufacture of ingots, tube billets, forgings, rolled rings, sheet and hot-rolled bars and strips intended for the manufacture of various components of heavy and power engineering.

Standards

Name	Code	Standards
Sheets and strips	В33	TU 14-1-109-71, TU 14-1-1556-76, TU 14-1-3179-81, TU 14-1-4461-88
Bars and shapes	В32	TU 14-1-1447-75, TU 14-1-2713-79
Welding and cutting metals. Soldering, riveting	В05	TU 14-1-2683-79
Blanks. Of the workpiece. Slabs	В31	TU 14-1-991-74, TU 14-1-2637-79, TU 14-1-871-74

Chemical composition

Standard	C	S	P	Mn	Cr	Si	Ni	Fe	Cu	V	Mo	W
TU 14-1-991-74	0.26-0.31	≤0.01	≤0.01	0.5-0.8	2.8-3.2	0.8-1.2	0.8-1.2	Rest	≤0.15	0.05-0.15	0.35-0.5	0.8-1.2
TU 14-1-871-74	0.26-0.31	≤0.01	≤0.02	0.5-0.8	2.8-3.2	0.9-1.2	0.9-1.2	Rest	≤0.15	0.05-0.15	0.35-0.5	0.8-1.2
TU 14-1-1447-75	0.26-0.31	≤0.01	≤0.015	0.5-0.8	2.8-3.2	0.9-1.2	0.9-1.2	Rest	≤0.15	0.05-0.15	0.35-0.5	0.8-1.2

Fe is the basis.
According to TU 14-1-871-74, the chemical composition is given for steel grade 28Х3СНМВФА-ВД (СП28-ВД).
According to TU 14-1-991-74 the chemical composition is given for steel grade 28Х3СНМВФА-ВД (СП28-ВД; ЭП326А-ВД). It is allowed to increase the content of sulfur and phosphorus by about 0010% with a total content of sulfur and phosphorus not more than 0.020%. Deviations in chemical composition are allowed: carbon ± 0.010%, manganese + 0.050 / -0.20%, silicon, chromium, nickel and tungsten ± 0.050% each, molybdenum ± 0.030%, vanadium +0.020%. Partial or complete replacement of tungsten with molybdenum is allowed, based on: 2.2 parts by weight of tungsten are replaced by one part by weight of molybdenum. When the tungsten is completely replaced, the molybdenum content should be in the range 0.75-0.95%.
According to TU 14-1-4461-88, the chemical composition of the steel should comply with the standards specified in Table 2 (Appendix 1), sent on request by the Central Research Institute of Chemical Technology named after Bardin. The sulfur content of sulfur is not more than 0.011%, phosphorus is not more than 0.015%, while the total content of sulfur and phosphorus should not be more than 0.022%. The residual copper content should not be more than 0.15%. With the consent of the consumer, it is allowed - up to 0.20%. In the finished sheets the following deviations in chemical composition from the norms indicated in Table 2 are allowed: carbon + 0.02 / -0.010%; tungsten ± 0.10%; manganese, silicon, chromium and nickel ± 0.050%; molybdenum ± 0.030%; vanadium +0.020%. Partial or complete replacement of tungsten by molybdenum from the calculation of 2.5 mass fraction of tungsten is allowed with one mass fraction of molybdenum.
According to TU 14-1-1447-75 the chemical composition is given for steel grade 28Х3СНМВФА (СП28). The sum of sulfur and phosphorus should not exceed 0.022%. It is allowed to increase the content of sulfur or phosphorus by 0.0010% with a total content of no more than 0.022%. Deviations in the established norms for the chemical composition are allowed: carbon ± 0.010%, chromium, nickel, silicon, manganese, tungsten ± 0.050%, molybdenum ± 0.030%, vanadium + 0.020%. Full or partial replacement of tungsten with molybdenum is allowed at the rate of 2.5 parts by weight of tungsten is replaced by one part by weight of molybdenum. When molybdenum is completely replaced by tungsten, the molybdenum content should be 0.75-0.95%. In the case of partial replacement of tungsten with molybdenum, the actual content of tungsten is recalculated to molybdenum in a ratio of 2.5: 1 and the conditional total molybdenum and tungsten content in terms of molybdenum should correspond to the specified molybdenum content when the tungsten is completely replaced. In steel without the replacement of tungsten by molybdenum, the residual molybdenum content of 0.10% is allowed. With the complete replacement of tungsten by molybdenum, the residual content of tungsten is allowed up to 0.15%.

Mechanical properties

Section, mm	s_T\|s_0,2, MPa	σ_U, MPa	d₅, %	y, %	KCU, kJ/m²
Ring clinocerinae on the other 14-1-2713-79. In the delivery condition specified cut direction samples. Annealing in air or air-blown with 930-980 °C + Vacation at 280-360 °C (delay 2-3 hours), air cooling
	≥1270	≥1570	≥7.8	≥32	≥392
	≥1270	≥1570	≥8.5	≥40	≥441
The leaves of g/K and x/K on the other 14-1-4461-88. Annealing in air or in oil with 930-980 °C + Vacation at 280-360 °C, air cooling (heating for hardening must eliminate the carburization and decarburization, the samples transverse)
	-	≥1570	≥7	-	-
Forgings on the other 14-1-991-74. Hardening in air, 930-980 °C + Vacation at 280-360 °C (delay 2-3 hours), air cooling
	≥1275	≥1570	≥8.5	≥40	≥490
	≥1275	≥1570	≥7.8	≥32	≥392
Bars and stripes on the other 14-1-1447-75. Quenching in oil with 930-980 °C + Vacation at 280-360 °C (delay 2-3 hours), air cooling
	≥1275	≥1570	≥8.5	≥40	≥490
Tubular billet on the other 14-1-2637-79. Annealing in air or in oil with 930-980 °C + Vacation at 280-360 °C (delay 2-3 hours), air cooling (longitudinal samples)
	-	≥1568	≥8.5	-	-

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

Technological properties

Name	The value
Machinability	In state after quenching and tempering Kn TV.SPL.=0,65 Kn b.St.=0,18.
Macrostructure and pollution	Microstucture steel pipe billet according to TU 14-1-2637-79 must conform to the standards GOST 4543 for stainless steel (steel open arc smelting) and abovetheline steel (steel of vacuum-arc remelting). Pollution steel non-metallic inclusions by the maximum score shall not exceed norms (for metal open arc smelting / metal vacuum-arc remelting): - oxides of stroke (OS) ≤ 4,0/2,0; - oxides of point () ≤ 4,0/2,0; - silicates fragile (CX) ≤ 4,0/2,0; - silicates plastic (SP) ≤ 4,0/1,0; - silicates, non-deformed (SN) ≤ 4,0/2,5; - sulphides (S) ≤ 3,5/2,0. Macrostructure of steel forgings on the other 14-1-991-74 when checking on the etched templeto cut from reforged control of the workpiece cross-section of 80-100 mm square, should not have traces of shrinkage, bubbles, cracks, inclusions, delaminations, and intergranular cracks visible to the naked eye. The macrostructure in the evaluation according to GOST 10243 on scales No. 1, 2, 3b, 4, 5, 6, 7 defects are not permitted above the first score, and the rating scales 9 and 10A is not above the third grade. Metal forgings should not be placenow visible to the naked eye. Pollution steel non-metallic inclusions as measured by scales GOST 1778 at a magnification of 100 times should not exceed average score for stroke oxides, oxides point, silicates fragile, sulphides and silicates, non-deformed 1,5 and 1,0 silicates plastic.
Particularities of production of goods	Bars (tubular billet) on the other 14-1-2637-79 are supplied in the annealed condition with not regulated and not controlled hardness.