Controlled cooling process and water cooler for high carbon and chromium bearing steel pipe blank after hot rolling

Abstract

The present invention belongs to the field of alloy steel and its making process, and is especially controlled cooling process and water cooler for high carbon and chromium bearing steel pipe blank after hot rolling. The cooling process includes the following steps: installing 4 water coolers in some interval on the cooling line and water cooling and air cooling the hot rolled pipe alternately in the V-shaped roll way; controlling the finishing temperature of rolled pipe blank to obtain single austenite structure before entering to the water coolers; ensuring the temperature of the hot rolled pipe blank before the first water cooler in 850-910 deg.c and the temperature leaving the fourth water cooler in 560+ / -20 deg.c; air cooling the pipe blank with surface temperature recovered to 650+ / -30 deg.c in the cooling bed; and fast spheroidizing annealing of the pipe blank. The present invention is superior to available technology.

Description

technical field [0001] The invention belongs to the field of alloy steel and its manufacturing process, and in particular relates to a controlled cooling process and a water cooler after hot-rolling of a high-carbon chromium bearing steel billet. Background technique [0002] In the existing technology, the controlled rolling and controlled cooling process of high carbon chromium bearing steel can be basically divided into three categories, the first category is high temperature rolling - controlled cooling; the second category is high temperature rolling - controlled cooling - isothermal rolling The third category is the low temperature rolling process. The isothermal rolling process of bearing steel must keep the temperature of the rolled piece constant, so it is necessary to increase the isothermal equipment, and the power and rigidity of the rolling mill are also required to be improved, so it is still difficult to practice in large-scale production. Low-temperature con...

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Problems solved by technology

In the past, in order to solve the problem of network carbides, the method of waiting for temperature before final rolling was adopted to achieve low-temperature final rolling, which greatly reduced the output of the rolling mill and deteriorated the production environment

And then a long spheroidizing annealing time is required. The spheroidizing annealing time is 20 to 22 hours, which not only increases the production cost, but also cannot obtain the ideal spheroidizing annealing structure, which has an adverse effect on the performance of the bearing steel.

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