MANUFACTURING METHOD OF STRIPS OF LOW-ALLOYED WELD STEEL Russian patent published in 2015 - IPC C21D8/02 C22C38/58 B21B1/26 

FIELD: metallurgy.

SUBSTANCE: rolling in a roughing train is performed till rolling thickness is at least 4.3 of thickness of a finished strip, finishing rolling is performed at the rolling beginning temperature equal to A_r3+70°C to A_r3+170°C, and coiling temperature is determined depending on rolling end temperature based on the following ratio: T_finish-370°C≤T_coiling≤T_finish-270°C. Steel contains the following, wt %: C = 0.05-0.11, Si = 0.30-0.65, Mn = 0.40-0.70, V = 0.04-0.12, Nb≤0.04, Al = 0.02-0.06, Ti≤0.03, Mo≤0.30, N≤0.008, Cr≤0.30, Ni≤0.30, Cu≤0.30, S≤0.005, P≤0.018, Ca = 0.001-0.006, Fe and impurities are the rest when the following ratios are met: Cr+Ni+Cu≤0.6 wt %, Nb+V+Ni≤0.15 wt %, Ca/S≥1. With that, steel structure includes ferrite with grain number of at least 9 at banding of not more than 2 points and non-metallic inclusions of not larger than 2.5 points.

EFFECT: increasing corrosion resistance, cold resistance and yield ratio of hot-rolled strips.

5 cl, 3 tbl, 1 ex