Steel austenite grain boundary display method and steel austenite grain size evaluation method

Abstract

The invention provides a steel austenite grain boundary display method and a steel austenite grain size evaluation method, and belongs to the technical field of steel structure analysis. The steel austenite grain boundary display method comprises the steps of heating a to-be-tested sample with a carbon content of 0.95-1.10wt% to a temperature higher than a preset critical temperature, carrying outheat preservation to completely austenitize the to-be-tested sample, putting the to-be-tested sample into a cooling liquid within 5s, and cooling at a speed of not less than 150 DEG C / s to obtain theto-be-tested sample with a cracked surface; and cutting the to-be-tested sample with the cracked surface to expose a fracture surface formed by cracking, and shooting a backscattered electron image of the fracture surface by using a backscattered electron probe. The steel austenite grain size evaluation method comprises the step of obtaining a back scattering electron image by adopting the display method; and evaluating the austenite grain size of the backscattered electron image by using an area method or an intercept point method. Metallographic sample preparation and corrosion treatment are not needed, and an austenite grain boundary line can be clearly displayed.

Description

technical field [0001] The present application relates to the technical field of iron and steel structure analysis, in particular, to a method for displaying austenite grain boundaries of steel and a method for evaluating austenite grain size of steel. Background technique [0002] Grain size is a measure of the grain size. The austenite grain size will affect the size and structure of the microstructure after the transformation of the subsequent heat treatment, and then affect the mechanical properties of the steel. Therefore, for the steel that needs to be heat treated, the austenite Grain size is an important index to measure the properties of steel. Metallographic method is currently a commonly used method for detecting austenite grain size. The current metallographic method needs to heat the steel to a certain temperature and hold it for a certain period of time, then cool it to room temperature in a certain way, and then carry out metallographic sample preparation, tha...

AI Technical Summary

Problems solved by technology

[0003] At present, when the metallographic method is used to detect the austenite grain size, due to the limitation of the etchant, the grain boundary and the structure are often displayed at the same time, making it difficult to distinguish the grain boundary. All are difficult to show, affecting the observation and evaluation of grain size

At present, the ideal etchant for grain boundary display is saturated picric acid etchant, but picric acid is a flammable and explosive reagent, it is difficult to purchase and requires a high storage environment

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