According to the metallurgical quality of CARBON structural steel Q235 in GB/T 700-2006, it is divided into four grades A, B, C and D, and the chemical composition of each grade steel is

Q235 Grade 4: A, B, C, D (GB/T 700-2006)

Q235A grade C 0.14-0.22% Mn 0.30-0.65% Si ≤0.30% S ≤ 0.050P ≤0.045

Q235B grade C 0.12-0.20% Mn 0.30-0.70%Si ≤ 0.30%S ≤ 0.045p ≤0.045

Q235C grade C ≤0.18% Mn 0.35-0.80% Si ≤0.30% S ≤ 0.040P ≤0.040

Q235D grade C ≤0.17% Mn 0.35-0.80% Si ≤0.30% S ≤ 0.035P ≤0.035

In China, there are many examples of cold working die with low carbon martensite rigid quenching process.

Mo-cr co-osmosis was carried out on the surface of the steel by double-glow ion metallizing technique, followed by supraturated carburizing, quenching and tempering. The thickness of Mo-Cr cap layer was over 100 microns, and the content of Mo and Cr on the surface was up to 20% and 10%, respectively. The carbon content on the supraturated carburizing surface was over 2.0%, and the surface composition was close to that of molybdenum high-speed steel. After quenching and tempering, the surface hardness is up to 1300HV, which exceeds the general metallurgical high speed steel. Wear tests show that the friction coefficient increases with the increase of contact stress, and the average relative wear resistance is 2.2 times that of GCr15 carburized and hardened steel.

1, can be used for all kinds of grinding tool handle and other unimportant grinding tool parts.

2, used to choose GCr15, 9SiCr, T8 and 45 steel, due to the workpiece bite die, stick die phenomenon, forging blank is difficult to rush out of the die, resulting in plastic deformation, bending and fracture punch, short life, every 10 punch about 800~1200 bolts; After the use of Q235 steel punch material, after quenching without tempering direct use, hardness of 36~40HRC, every ten pieces of punch can be more than 2000 pieces of bolt, and the failure form for plastic deformation, to solve the phenomenon of the punch in use, to ensure the operator's personal safety.