Modern large-scale cold strip mill has realized endless and semi endless rolling. The requirements for strip quality, such as surface flatness and thickness difference of cold-rolled strip, are higher and higher, and the requirements for work roll quality are also higher and higher. The requirements for surface hardness and hardened layer depth are greatly improved. The research of cold rolling work roll material has been highly valued by the roll industry, from the initial bearing steel gradually developed to 2% Cr, 3% Cr, 5% Cr section steel, its development is usually characterized by the continuous improvement of chromium content. In recent years, semi high speed steel and high speed steel roll materials have appeared, and the research on their microstructure and carbides has been reported. The technical personnel of Anhui huanbowan high speed steel roll Co., Ltd. studied the quenching process of a newly developed forging high speed steel cold rolling work roll material, analyzed the influence of quenching temperature on the microstructure, grain size, retained austenite and hardness of high speed steel roll, and provided theoretical and experimental basis for the development of high-end cold rolling work roll.
The new forged high speed steel roll material was melted in 50kg vacuum induction furnace, then forged into 100 mm × 100 mm × 250 mm billet at high temperature, and the original material was obtained after annealing at 700 ℃ for 4 h. The metallographic sample is 15mm × 15mm × 15mm square. The box resistance furnace is used for heating at different temperatures and air cooling quenching. Hardness was measured by 660rld / T Rockwell hardness tester, retained austenite was measured by x'perpro X-ray diffractometer, microstructure and grain size were measured by axiovert 200mat optical microscope, and carbide was observed by Quanta 400 scanning electron microscope.
The as cast microstructure of the new forged high speed steel roll is lower bainite + ledeburite + a small amount of martensite + strip car