The current GB/T 700 standard and old GB 700 standard GangHao comparison

GB/T 700-1988 standard
GB 700-1979 standard

steel

number
Technology conditions
Steel grade
Technology conditions

Q195
Regardless of rank, the chemical composition and mechanical properties (σ s, σ b, the delta and the cold bending) are to be guaranteed

Rolling plate and rod of products, the mechanical properties of the guarantee condition, can according to product characteristics and application requirements, in the standard separately
A1

B1
A1 the mechanical properties of the steel guarantee (σ s, σ b, the delta and the cold bending), B1 steel guarantee the chemical composition of the same with Q195

A1 steel cold bending test is additional guarantee conditions

1 no special steel of steel

Q215
Points A, B, grade, the provisions of the chemical composition and performance should ensure that all learn force

Q215A not impact test

Q215B shall be room temperature concussion test, the gap with V
A2

C2
A2 steel the mechanical properties of the guarantee, C2 steel guarantee the chemical and mechanical properties and Q215 basic same

Q235
Points A, B, C, D level, the provisions of the chemical composition and mechanical properties shall be guaranteed

Q235A not impact test

Q235B shall be room temperature concussion test, the gap with V

Q235C, Q235D used for important welding structure, the former at 0 ° be instrumented impact test, the latter in-20 ° for impact test sample is alexandrine
A3

C3
A3 steel guarantee mechanical properties and chemical composition of the C3 steel guarantee and mechanical properties, and basically the same of Q235 steel

A3 steel at additional guarantee impact test sample with U shape gap

C3 steel additional guarantee normal temperature 20 ℃ or-impact test sample is alexandrine

Q255
Points A, B level, the provisions of the chemical composition and mechanical properties shall be guaranteed

Q255A not impact test

Q255B shall be room temperature concussion test, the gap with V
A4

C4
A4 steel the mechanical properties of the guarantee, C4 steel the chemical composition of the guarantee and mechanical properties, and Q255 steel basic same

C4 steel additional guarantee impact test sample with U shape gap

Q275
Regardless of rank, the provisions of the chemical composition and mechanical properties shall be guaranteed
C5
The C5 steel guarantee the chemical and mechanical properties, and basically the same Q275 steel