Steel U8A
Designation
Name |
The value |
Designation GOST Cyrillic |
У8А |
Designation GOST Latin |
U8A |
Transliteration |
U8A |
The chemical elements |
8 |
Description
U8A steel is used: for the manufacture of tools, working in conditions without heating of cutting edge; the tool for tree processing (milling cutters, countersinks, zekovic, axes, chisels, chisels, longitudinal, and circular saws; rollers, plates and rods for mold molding tin-swinomish alloys; calibers simple form and low accuracy classes; cold-rolled heat-treated ribbon with a thickness of from 2.5 to 0.02 mm, intended for manufacturing of flat and wire springs and spring-loaded parts of complex configuration (valves, styli, reeds, slats dolnych knives structural fine details, including hours, etc. (tape is produced according to GOST 2283, GOST 21996 and a number of special technical conditions); 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 the crown; measuring tapes.
Standards
Name |
Code |
Standards |
Sheets and stripes |
В23 |
GOST 103-2006 |
Sectional and shaped rolling |
В22 |
GOST 1133-71, GOST 2590-2006, GOST 2591-2006, GOST 2879-2006 |
Sectional and shaped rolling |
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 |
Tapes |
В34 |
GOST 2283-79, GOST 10234-77, GOST 21996-76, GOST 21997-76, TU 3-939-81, TU 14-1-2993-80, TU 14-1-3656-83, TU 14-175-80-89, TU 14-175-81-89, TU 14-4-99-73 |
Sheets and stripes |
В33 |
GOST 4405-75, TU 14-19-81-90, TU 14-131-971-2001 |
Steel wire medium- and high-carbon |
В72 |
GOST 5468-88, GOST 9389-75 |
Classification, nomenclature and general norms |
В20 |
OST 1 90005-91 |
Bulls. Blanks. Slabs |
В31 |
TU 14-1-3300-81 |
Tapes |
В24 |
TU 14-4-104-72 |
Chemical composition
Standard |
C |
S |
P |
Mn |
Cr |
Si |
Ni |
Fe |
Cu |
GOST 1435-99 |
0.75-0.84 |
≤0.018 |
≤0.025 |
0.17-0.28 |
≤0.2 |
0.17-0.33 |
≤0.25 |
The 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 in the steel grade U8A, intended for the manufacture of wire for the metal cord, the carbon content should be 0.74-0.80%. By agreement of the parties for special purpose hardware, steel must be supplied with reduced content limits of elements without treatment with synthetic slag and purging with argon.
For the tape according to TU 14-1-2993-80 produced in accordance with GOST 2283, the deviation in chromium content is allowed up to +0,020%.
Mechanical characteristics
Section, mm |
sT|s0,2, MPa |
σB, MPa |
d5, % |
d4 |
d |
y, % |
Brinell hardness number, MPa |
HRC |
HV, MPa |
Tape flatted average strength of 0.1-4.0 mm according to GOST 10234-77 in the state of delivery (indicated delivery) |
- |
- |
740-1270 |
- |
- |
- |
- |
- |
- |
- |
- |
- |
≤780 |
- |
- |
≥8 |
- |
- |
- |
- |
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 |
Cold-rolled steel strip sagatovna (specified strength class) |
0.1-4 |
- |
750-900 |
- |
- |
- |
- |
- |
- |
- |
Quenching in oil from 780 °C to + Leave at 400 °C (samples a smooth diameter 6.3 mm) |
- |
≥1230 |
≥1420 |
≥10 |
- |
- |
≥37 |
- |
- |
- |
Gradation of performance properties of the finished heat-treated parts for OST 1 90005-91 |
- |
- |
- |
- |
- |
- |
- |
- |
44-48 |
- |
Cold-rolled steel strip sagatovna (specified strength class) |
0.1-4 |
- |
900-1050 |
- |
- |
- |
- |
- |
- |
- |
Quenching in oil from 780 °C to + Leave at 400 °C (samples a smooth diameter 6.3 mm) |
- |
≥1270 |
≥1450 |
≥11 |
- |
- |
≥36 |
- |
- |
- |
Cold-rolled steel strip sagatovna (specified strength class) |
0.1-4 |
- |
1050-1200 |
- |
- |
- |
- |
- |
- |
- |
Quenching in oil from 780 °C to + Leave at 400 °C (samples a smooth diameter 6.3 mm) |
- |
≥1300 |
≥1470 |
≥12 |
- |
- |
≥35 |
- |
- |
- |
Cold-rolled steel strip of 0.1-4.0 mm according to GOST 2283-79 on delivery |
0.1-4 |
- |
740-1180 |
- |
- |
- |
- |
- |
- |
- |
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 |
≥58 |
- |
- |
≥91 |
- |
- |
- |
Cold-rolled steel strip of 0.1-4.0 mm according to GOST 2283-79 on delivery |
0.1-1.5 |
- |
≤640 |
- |
≥15 |
- |
- |
- |
- |
- |
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 |
- |
- |
≥91 |
≥58 |
- |
- |
≥100 |
- |
- |
- |
Cold-rolled steel strip of 0.1-4.0 mm according to GOST 2283-79 on delivery |
1.5-4 |
- |
≤740 |
- |
≥10 |
- |
- |
- |
- |
- |
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 |
- |
- |
≥55 |
≥62 |
- |
- |
≥100 |
- |
- |
- |
Cold-rolled steel strip of 0.1-4.0 mm according to GOST 2283-79 on delivery |
1.5-4 |
- |
≤640 |
- |
≥10 |
- |
- |
- |
- |
- |
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 |
- |
- |
≥33 |
≥62 |
- |
- |
≥100 |
- |
- |
- |
- |
- |
≥21 |
≥80 |
- |
- |
≥100 |
- |
- |
- |
- |
- |
≥15 |
≥69 |
- |
- |
≥100 |
- |
- |
- |
Annealing or normalizing |
- |
- |
≤710 |
≥17 |
- |
- |
≥24 |
≤195 |
- |
- |
- |
- |
≤640 |
≥15 |
- |
- |
≥15 |
≤205 |
- |
- |
- |
- |
≤580 |
≥17 |
- |
- |
≥16 |
≤205 |
- |
- |
- |
- |
≤540 |
≥19 |
- |
- |
≥23 |
≤190 |
- |
- |
- |
- |
≤500 |
≥23 |
- |
- |
≥29 |
≤170 |
- |
- |
- |
- |
≤370 |
≥28 |
- |
- |
≥39 |
≤150 |
- |
- |
- |
- |
≤255 |
≥33 |
- |
- |
≥50 |
≤120 |
- |
- |
Description mechanical marks
Name |
Description |
Section |
Section |
sT|s0,2 |
Yield strength or limit of proportionality with a tolerance for residual deformation of 0.2% |
σB |
Limit short-term strength |
d5 |
Elongation after rupture |
d4 |
Elongation after rupture |
d |
Elongation after rupture |
y |
The relative narrowing |
HRC |
Rockwell hardness (indenter diamond spheroconical) |
HV |
The Vickers hardness |
Physical characteristics
Temperature |
Е, ГПа |
G, ГПа |
r, кг/м3 |
l, Вт/(м · °С) |
R, НОм · м |
a, 10-6 1/°С |
С, Дж/(кг · °С) |
0 |
209 |
81 |
7839 |
- |
- |
- |
- |
100 |
205 |
80 |
7817 |
49 |
230 |
114 |
477 |
200 |
199 |
77 |
7786 |
46 |
305 |
122 |
511 |
300 |
192 |
74 |
7752 |
42 |
395 |
13 |
528 |
400 |
185 |
71 |
7714 |
38 |
491 |
137 |
548 |
500 |
175 |
67 |
7676 |
35 |
625 |
143 |
565 |
600 |
166 |
62 |
7638 |
33 |
769 |
148 |
594 |
700 |
- |
- |
7600 |
30 |
931 |
152 |
624 |
800 |
- |
- |
7852 |
24 |
1129 |
145 |
724 |
900 |
- |
- |
- |
25 |
1165 |
- |
- |
1000 |
- |
- |
- |
- |
- |
152 |
724 |
1200 |
- |
- |
- |
- |
- |
157 |
703 |
A description of the physical symbols
Name |
Description |
Е |
The normal elasticity modulus |
r |
Density |
l |
Coefficient of thermal conductivity |
R |
UD. the resistivity |
a |
The coefficient of linear expansion |
С |
Specific heat |
Technological properties
Name |
The value |
Weldability |
Does not apply to welded structures. Method of welding - CCC. |
Propensity to temper brittleness |
tend not |
Forging temperature |
Start - 1180 °C, the end - of 800 °C. the cooling of the workpiece cross-section up to 100 mm in the air, 101-300 mm in the pit. |
Flock-sensitive sensitivity |
not sensitive. |
Workability by cutting |
When NV 187-227 Kn TV.SPL.=1,2 Kn b.St.=1,1. |
Microstructure |
The microstructure of the untreated strips with thickness up to 2.2 mm on the other 14-1-2993-80 must meet: lamellar pearlite is not more than 6 points; tsementita mesh - no more than 3 points. |
Features of production |
Rod on the other 14-1-505-73 comes Makiivka metallurgical plant. |
Grindability |
Good. |