GB/T 37601-2019Hot rolled steel sheet and strip of alloy structure steel (English PDF)

5.1.2

The thickness allowable deviation is implemented according to the thickness allowable deviation of steel strips (including continuous rolled steel sheets) with minimum yield strength Re greater than 360 MPa as specified in

5.1.3

The flatness is agreed upon between the supply and demand parties and indicated in the contract.

5.1.4

Agreed upon between the supply and demand parties, steel of other dimensions, shapes and allowable deviations may be supplied.

5.2 Narrow steel strips and shear steel sheets

The dimension, shape, weight and allowable deviation of narrow steel strips and shear steel sheets shall comply with the provisions of Annex A.

6.1 Designation and chemical composition

6.1.1

The designation and chemical composition of steel (melting analysis) shall comply with the provisions of Table 1. See Annex B for the comparison of similar designations with relevant standards.

6.1.2

When Cr, Ni, Cu and Mo in steel are taken as residual elements, the Cr,

Ni and Cu contents shall not exceed 0.30 % respectively and the Mo content shall not exceed 0.10 %. If it can be guaranteed by the supply party, the analysis may be exempted.

6.1.3

The P content in steel shall not exceed 0.030 %, and the S content shall not exceed 0.020 %.

6.1.4

The allowable deviation of chemical composition of finished steel sheets and strips shall comply with the provisions of GB/T 222.

6.1.5

Agreed upon between the supply and demand parties, the supply party may provide other designations other than those specified in Table 1. The designations and chemical composition shall comply with the provisions of

the provisions of Table 3. If the demand party has a higher level requirement, the qualification level shall be determined by agreement between the supply and demand parties.

Table 3 -- Non-metallic inclusions

Class A Class B Class C Class D

Thin series Thick series Thin series Thick series Thin series Thick series Thin series Thick series

6.8 Surface quality

6.8.1

The surface of steel sheets and strips shall be free of cracks, blisters, folding, inclusions, crusting or obvious scratches. Steel sheets and strips shall not have visible laminations. If the above surface defects are present, the removal is allowed, and the removal depth shall not exceed half the thickness tolerance of steel sheets and strips. Other defects are allowed, but the depth and height shall not exceed half the thickness tolerance of steel sheets and strips, and the minimum thickness of steel sheets and strips shall be guaranteed.

6.8.2

During the continuous production of steel strips, local surface defects are not easily found and removed, thus allowing delivery with defects, but the defective portion shall not exceed 6 % of the total length of each coil of steel strip.

6.8.3

Surface quality characteristics of steel sheets and strips shall comply with the requirements of Table 4.

Table 4 -- Surface quality characteristics of each grade

Grade and code

Applicable surface treatment method

Characteristics

Normal grade surface (FA)

Rolled surface

Pickled surface

The surface is allowed to have slight or local defects such as pitting, concave, scratches with a depth (or height) not exceeding half the thickness tolerance of the steel strip, and the minimum allowable thickness of the steel sheet and strip shall be ensured.

It is allowed to have local defects such as slight jagged edges, partially uncut edges, under pickling, over pickling and parking spots

Higher grade surface (FB) Pickled surface

The surface is allowed to have local defects that do not affect the formability, such as: slight scratches, slight indentations, slight pitting, slight roll marks and chromatic aberration. The surface is allowed to have slight parking spot that is not obvious after oiling. It is not […]