The specified content of any element specified in steel conforms to the limit value range of the corresponding elements of non-alloy steel, low alloy steel and alloy steel, and these steels are referred to as non-alloy steel, low alloy steel and alloy steel.

1 non-alloy steel includes carbon steel (ordinary carbon structural steel, high-quality carbon structural steel, carbon tool steel, carbon spring steel, free-cut carbon structural steel), pure iron (electrical pure iron, raw pure iron) ) and other special non-plate steel with special properties.

2 The heat treatment is not specified, but the annealing, normalizing, stress relieving, and softening treatment are not treated as heat treatment.

3 If the product standard or technical conditions stipulate, the characteristic value shall meet the following conditions:

The highest carbon content ≥0.10%

The highest sulfur and phosphorus content ≥0.045%

The highest nitrogen content ≥0.007%

The lowest tensile strength ≤ 690MPa

Minimum yield point or yield strength ≤360MPa

The lowest elongation (Lo = 5.65) ≤ 33%

Minimum diameter of the bending center ≥0.5X thickness of the test piece

The lowest impact energy (20 ° C, V-shaped, longitudinal standard sample) ≤ 27J

Rockwell hardness highest value (HRB) ≥60

The above specified values of mechanical properties refer to the properties measured by longitudinal or transverse specimens made of steel having a thickness of 3 to 16 mm.

4 No other quality requirements are specified.