Grade Y12
China ISC U71122
Corresponding Standard GB /T 8731-2008
Free-Cutting Structural Steel
Classification Carbon Steel
Y12 Chemical Element Composition Content (%)
Component C Si Mn P S
Minimum Value 0.08 0.15 0.7 0.08 0.1
Maximum Value 0.16 0.35 1 0.15 0.2
Y12 Mechanical Properties
diameter
d
mm
Heat Treatment or Condition
Tensile Strength
σb
Mpa
Elongation or Extension Rate
δ
%
Reduction of Area
ψ
%
Hardness
HBW
d=20 (Sample Diameter) Hot Rolled Delivery Condition 390~540 ≥22 ≥36 ≤170
d = 8~20 (steel size) Cold Drawn State Delivery 530~755 ≥7 152~217
d > 20 ~ 30 (steel size) Cold Drawn State Delivery 510~735 ≥7 152~217
d > 30 (steel size) Cold Drawn State Delivery 490~685 ≥7 152~217
New and Old Grade Replacement List
Corresponding Standard Grade
GB /T 8731-2008
Grade
China ISC
GB /T 8731-2025
Grade
China ISC
1 Approximate Comparison Table Free-Cutting Structural Steel
China Taiwan, China Japan South Korea United States International Organization for Standardization Germany France Russia
GB ISC CNS JIS KS ASTM/AISI ISO DIN EN/DIN W-Nr. NF EN/NF GOST
Y12 U71122 SUM21 SUM21 SUM21 B1112
1211①
10S20 10S20 1.0721 13MF4 А12
2 Approximate Comparison Table Free-Cutting Structural Steel
China United States Germany France European Standard Sweden United Kingdom
GB ASTM/AISI DIN EN/DIN W-Nr. NF EN/NF EN Numerical Grade SS BS EN/BS
Y12 Gr.1108 10S20 1.0721 10F1 10S20 1.0721 1912 210M15
3 Approximate Comparison Table Free-Cutting Structural Steel
China Japan United States International Organization for Standardization Russia
GB ISC JIS ASTM/AISI ISO GOST
Y12 U71122 SUM12 1211
1212
10S20 A12
4 Approximate Comparison Table High-Quality Carbon Structural Steel
China United States
GB ASTM/AISI
Y12 1214
Y12 Corresponding Standards(Same grade name, different standards)

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