Preparation method of sample for detecting austenite grain size of steel by oxidation method

Abstract

The invention discloses a preparation method of a sample for detecting austenite grain size of steel by an oxidation method. The preparation method comprises the steps of (1) taking the sample; (2) polishing the detection surface of the sample; (3) placing the polished sample detection surface upwards in a furnace for heat treatment, heating the sample with the carbon content (mass fraction) not larger than 0.35% at the temperature of 890 + / -10 DEG C, heating the sample with the carbon content (mass fraction) larger than 0.35% at the temperature of 860 + / -10 DEG C, and carrying out quenching in cold water or saline water after heat preservation is conducted for 1 h; (4) dropwise adding a hydrochloric acid solution to the detection surface of the sample subjected to heat treatment, and after bubbles appear on the surface of the sample, washing with clear water and blow-drying; (5) polishing the detection surface; and (6) corroding by using a 15% hydrochloric acid alcohol solution, washing by using the alcohol solution, and drying for later detection. The sample obtained by the method is larger in detection area and higher in sample preparation success rate.

Description

technical field [0001] The invention relates to a method for preparing a sample for detecting the austenite grain size of steel, in particular to a method for preparing a sample for detecting the austenite grain size of steel by an oxidation method. Background technique [0002] The direct hardening method is the best and most convenient method for detecting the austenite grain size of steel, which is recognized as the most accurate austenite grain size detection method at home and abroad. The direct hardening method uses a supersaturated picric acid solution to corrode the austenite grain size, but picric acid is a kind of explosive. As the country's control of toxic and explosive substances becomes stricter, picric acid will not be able to be purchased; this The use of methods that result in hardening to reveal austenite grain size is limited. There is an urgent need to use other methods for the detection of austenite grain size in iron and steel materials. [0003] The ...

AI Technical Summary

Problems solved by technology

The standard recommended method is to incline the test surface of the sample by 10° to 15° according to the oxidation condition, lightly grind with sandpaper and polish to remove the oxide scale on the test surface. In this method, it is difficult to grasp the proper inclination of 10° to 15° in manual sample preparation , either the degree of removal of the oxide scale on the detection surface is insufficient, or the removal of the oxide scale on the detection surface is excessive and the grain boundary oxidation network layer is also removed, or only a small area of ​​the grain boundary oxide layer remains, which leads to the failure of sample preparation. Once the surface oxide layer of the particle size sample is worn away, it can only be re-sampled, re-heat-treated, and re-grinded, which greatly increases the inspection cycle and consumes a lot of manpower and material resources.

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