Steel U12A

Designation

Name	The value
Designation GOST Cyrillic	У12А
Designation GOST Latin	U12A
Transliteration	U12A
By chemical elements	12

Description

Steel U12A is used: for the manufacture of cores; hand taps, files, metal scrapers; parts dies of cold forming, trimming and punching of small size and no transitions in the cross section; cold forging punches and dies for small sizes; calibers simple form and low accuracy classes; tools with low wear resistance at moderate and high specific pressure (without heating the cutting edge): nail files, razor blades and knives, sharp surgical tools, scrapers, engraving tools; cold-rolled heat-treated ribbon with a thickness of 0.05 to 1.30 mm and rolled heat-treated strip thickness 0.15−2.00 mm for the manufacture of spring details and springs, with the exception of clockwork.

Standards

Name	Code	Standards
Sheets and strips	В23	GOST 103-2006
Bars and shapes	В22	GOST 1133-71, GOST 2590-2006, GOST 2591-2006, GOST 2879-2006
Bars and shapes	В32	GOST 1435-99, GOST 5210-95, GOST 7417-75, GOST 8559-75, GOST 8560-78, GOST 14955-77, TU 14-1-505-73, TU 14-11-245-88, TU 14-1-1271-75
Tape	В34	GOST 21996-76, GOST 21997-76
Sheets and strips	В33	GOST 4405-75
Steel wire medium and high carbon	В72	GOST 5468-88, GOST 9389-75

Chemical composition

Standard	C	S	P	Mn	Cr	Si	Ni	Fe	Cu
GOST 1435-99	1.1-1.29	≤0.018	≤0.025	0.17-0.28	≤0.2	0.17-0.33	≤0.25	Rest	≤0.25

Fe is the basis.
According to GOST 1435-99, the mass fraction of chromium, nickel and copper is indicated for 1 group of metal products. The mass fraction of sulfur in steel obtained by the electroslag remelting method should not exceed 0.013%. In the metal products of the 2nd group, the mass fraction of Cr ≤ 0.12%, Ni ≤ 0.12%, Cu ≤0.20% and their total mass fraction ≤ 0.40%. In the metal products of the third group, the mass fraction of Cr ≤ 0.20-0.40%, Ni ≤ 0.25%, Cu ≤0.25%. In metal products of the 1 st and 3 rd groups, made of steel obtained by scrap-process, the mass fractions of nickel, copper and chromium are increased by 0.05% of each element as compared to those in the table. In a metal designed for the manufacture of cold-rolled strip, an increase in the mass fraction of nickel, copper and chromium is not allowed.
According to TU 14-1-505-73, by agreement of the parties for special purpose hardware, steel should be supplied with reduced content limits of elements without treatment with synthetic slag and purging with argon.

Mechanical properties

Section, mm	t отпуска, °C	s_T\|s_0,2, MPa	σ_U, MPa	d₅, %	d₄	y, %	KCU, kJ/m²	HRC	HV, MPa
Tape cold-rolled heat-treated (0,05-1,30 mm) for spring parts and springs according to GOST 21996-76 and flattened strip (0,15-2,00 mm) according to GOST 21997-76 (listed group strength tape)
-	-	-	1270-1570	-	-	-	-	-	375-485
-	-	-	1580-1860	-	-	-	-	-	486-600
-	-	-	≥1860	-	-	-	-	-	≥600
Annealed cold-rolled tape of the highest quality
0.08-3	-	-	≤750	-	≥10	-	-	-	-
Samples section 21-30 mm. Quenching in water 810-830 °C + Vacation
-	400	≥1370	≥1570	≥9	-	≥24	≥20	≥52	-
A sample with a diameter of 5 mm and a length of 25 mm, the deformed and annealed. The rate of deformation of 10 mm/min strain Rate 0,007 1/C
-	-	-	≥105	≥60	-	≥68	-	-	-
Samples section 21-30 mm. Quenching in water 810-830 °C + Vacation
-	500	≥880	≥1040	≥11	-	≥30	≥29	≥40	-
A sample with a diameter of 5 mm and a length of 25 mm, the deformed and annealed. The rate of deformation of 10 mm/min strain Rate 0,007 1/C
-	-	-	≥100	≥52	-	≥96	-	-	-
Samples section 21-30 mm. Quenching in water 810-830 °C + Vacation
-	600	≥650	≥760	≥18	-	≥52	≥44	≥26	-
A sample with a diameter of 5 mm and a length of 25 mm, the deformed and annealed. The rate of deformation of 10 mm/min strain Rate 0,007 1/C
-	-	-	≥60	≥40	-	≥100	-	-	-
-	-	-	≥34	≥65	-	≥100	-	-	-
-	-	-	≥18	≥74	-	≥100	-	-	-
-	-	-	≥15	≥92	-	≥100	-	-	-
Rolled steel. Annealing (at 20 °C HB=207)
-	-	≥325	590-690	≥28	-	45-55	-	-	-
-	-	≥320	≥570	≥23	-	≥47	-	-	-
-	-	≥310	≥450	≥41	-	≥60	-	-	-
-	-	≥110	≥140	≥56	-	≥74	-	-	-
-	-	≥59	≥76	≥56	-	≥82	-	-	-
-	-	≥53	≥72	≥59	-	≥85	-	-	-
-	-	≥34	≥40	≥52	-	≥91	-	-	-
-	-	≥20	≥28	≥55	-	≥98	-	-	-

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
d₄	Elongation after rupture
y	The relative narrowing
KCU	Toughness
HRC	Rockwell hardness (indenter diamond spheroconical)
HV	The Vickers hardness

Physical characteristics

Temperature	Е, HPa	G, HPa	r, kg/m³	l, W/(m · °C)	R, Mr. · m	a, 10^-6 1/°C	С, J/(kg · °C)
0	209	82	7830	-	-	-	-
100	205	80	7809	45	252	105	469
200	200	78	7781	43	333	118	503
300	193	75	7749	40	430	126	519
400	185	72	7713	37	540	134	536
500	178	69	7675	35	665	141	553
600	166	63	7634	32	802	148	720
700	-	-	7592	28	964	153	611
800	-	-	7565	24	1152	15	712
900	-	-	7489	25	1196	-	-
1000	-	-	-	-	-	163	703
1200	-	-	-	-	-	168	699

A description of the physical symbols

Name	Description
Е	The normal elasticity modulus
G	Modulus of elasticity shear torsion
r	Density
l	Coefficient of thermal conductivity
R	UD. the resistivity
a	The coefficient of linear expansion

Technological properties

Name	The value
Weldability	Does not apply to welded structures. Method of welding - CCC.
Склонность к отпускной хрупкости	Tend not.
The temperature of forging	Start - 1100 °C, the end - 750 °C. slow Cooling in air.
Flock-sensitive sensitivity	not sensitive.
Machinability	In the annealed condition with HB 207 Kn TV.SPL.=1,0 Kn b.St.=0,9.
Particularities of production of goods	Rod on the other 14-1-505-73 comes Beloretsky metallurgical plant.
Sanding behaviour	Good.