Displaying method of hot-rolled product austenite grains

Abstract

The invention discloses a displaying method of hot-rolled product austenite grains. The displaying method includes the steps that (1) a sample is taken, specifically, the sample is taken from a hot-rolled product to be detected; (2) heat treatment is carried out, specifically, the sample is loaded into a heating furnace under the furnace temperature of 500 DEG C or below and heated to 930 DEG C orabove with the furnace, heat preservation is carried out for 3 hours or above, and the sample is out of the furnace to be water-cooled; and (3) corrosion is carried out, specifically, after heat treatment, the sample is cut, ground, polished, and then corroded by a corrosive agent until a grain boundary is corroded to be clear. According to the displaying method of the hot-rolled product austenite grains, by changing the charging temperature of 930 DEG C or above, the charging sample at 500 DEG C or below is adopted to be heated slowly with the furnace, thus carbides in the hot-rolled productare separated out preferentially along the grain boundary, growth of the austenite grains can be prohibited effectively, the smaller grains are obtained, thus the grain size is changed from a mixed-grain state to a uniform-grain state, coarse grains are changed to the fine grains, the inspection qualification rate of the hot-rolled product austenite grain size is effectively increased, and the qualification rate reaches 90% or above.

Description

technical field [0001] The invention relates to the field of grain size inspection, in particular to a method for displaying austenite grains of a hot-rolled material. Background technique [0002] The inspection of austenite grain size of hot-rolled materials produced by various domestic enterprises is mainly based on GB / T6394-2017 "Metal Average Grain Size Inspection Method", and the laboratories of various enterprises usually use the direct hardening method in this method to inspect austenite grain size. According to this method, the hot-rolled material is usually heat-treated after the furnace reaches the set temperature, and the pass rate of the austenite grain size is greater than 95%. However, some customers of hot-rolled materials proposed that the austenite grain size should be at 930°C or above, and the heat preservation time should be 3h or above, and the inspection should be carried out after water cooling, complete hardening and quenching. Using the above metho...

AI Technical Summary

Problems solved by technology

However, some customers of hot-rolled materials proposed that the austenite grain size should be at 930°C or above, and the heat preservation time should be 3h or above, and the inspection should be carried out after water cooling, complete hardening and quenching. Using the above method to check the grain size is prone to mixed crystal phenomenon, and the pass rate is only 63%. about

Images