Yield strength 700MPa grade atmospheric corrosion resistant steel and method for manufacturing same

Abstract

The atmospheric corrosion resistant steel with yield strength of 700 MPa level has the chemical composition comprising C 0.05-0.10 wt%, Si not more than 0.50 wt%, Mn 0.8-1.6 wt%, P not more than 0.020 wt%, S not more than 0.010 wt%, Al 0.01-0.05 wt%, Cu 0.20-0.55 wt%, Cr 0.40-0.80 wt%, Ni 0.12-0.40 wt%, Ca 0.001-0.006 wt%, N 0.001-0.006 wt% and Fe and inevitable impurity for the rest. Its production process includes the following steps: 1. smelting and casting to form steel billet; 2. heating the steel billet to over 1200 deg.c, finish rolling at 950 deg.c in the final temperature lower than 910 deg.c and lowered with the increased plate thickness; and 3. cooling in the rate of 5-15 deg / s to 450-650 deg.c, winding and air cooling to room temperature. The atmospheric corrosion resistant steel has excellent comprehensive mechanical performance, yield strength over 700 MPa, high weather resistance and other advantages.

Description

technical field [0001] The invention relates to the field of low-alloy steel manufacturing, in particular to ultra-high-strength atmospheric corrosion-resistant steel with a yield strength of 700 MPa and a manufacturing method thereof. Background technique [0002] Atmospheric corrosion-resistant low-alloy structural steel is widely used in outdoor steel structure manufacturing fields such as buildings, bridges, containers, vehicles, and masts. It is based on low-carbon manganese steel, adding a small amount of low-alloy corrosion-resistant elements such as Cr, Cu, Ni, etc., to promote the change of the rust layer structure of the steel, which is beneficial to slow down the atmospheric corrosion rate and significantly improve the atmospheric corrosion resistance of the steel. [0003] Chinese Patent Application No. 200410061112.4 discloses "high-strength weathering steel with needle-like structure and its production method". Add two or more of them in combination to control...

AI Technical Summary

Problems solved by technology

Although the patent also adopts Cu-Cr-Ni weather resistance composition design and Nb-Ti-Mo micro-alloy design, but the patent specifically adds V element 0.06-0.14%. Adding V element not only greatly increases the manufacturing cost, but also does not It is beneficial to the welding performance and low temperature impact performance of the steel plate