Manufacturing method of increasing high strength flat-bulb steel low temperature impact properties percent of pass

Abstract

The invention discloses a production method for improving low temperature impact property qualified rate of high strength ball flat steel, which consist of steps of rough rolling, finish rolling, final rolling and cooling after rolling. The web temperature of the final rolling is ranging from 870 DEG C to 930 DEG C and the ball-end temperature is ranging from 910 DEG C to 990 DEG C. For cooling after rolling, air cooling is adopted. By controlling the final rolling temperature and speed of the cooling after rolling, the invention eliminates or reduces granular bainite and widmanstatten in the microstructure of the ball flat steel, thereby greatly improving the low temperature impact property qualified rate of the high strength ball flat steel.

Description

technical field

[0001] The invention relates to a production method of high-strength flat bulb steel, in particular to a production method for improving the qualified rate of low-temperature impact performance of high-strength flat bulb steel. Background technique

[0002] High-strength bulb flat steel is a special profile for the shipbuilding industry. Due to the vigorous development of the domestic shipbuilding industry, the demand for bulb flat steel has also increased accordingly. However, the low pass rate of high-strength bulbous flat steel A36 and D36 has been perplexing the production of section steel. From the production situation, the pass rate of the initial test is only 87.8%. economic loss. According to statistical analysis, the main problem of high-strength bulbous flat steel is the unstable low-temperature impact performance, and the unqualified low-temperature impact performance is the main reason affecting the qualified rate of high-strength bulbous flat s...