Method for displaying original austenitic grain boundary of martensitic heat-resistant steel

Abstract

The invention relates to a method for displaying an original austenitic grain boundary of martensitic heat-resistant steel, and belongs to the technical field of metallographic sample preparation. The method comprises the process steps of polishing and etching. A polished sample is put into an etching agent, the etching time is 5 to 10 seconds, and the sample is taken out when copper decorating the surface of the sample is observed, washed cleanly by alcohol and dried by blowing; and the clear original austenitic grain boundary can be observed under a metallographic microscope. According to the formula, the etching agent comprises the following components: 5 to 15 g of copper sulfate pentahydrate, 30 to 50 ml of hydrochloric acid and 50 to 70 ml of deionized water. The method has the advantages that the clear original austenitic grain boundary of the martensitic heat-resistant steel can be etched out at normal temperature while a martensitic structure is not displayed, the method is convenient to operate, and the corrosion rate of austenite is higher than that of picric acid solution.

Description

technical field [0001] The invention relates to a method for displaying the original Austrian grain boundary of a martensitic heat-resistant steel at room temperature. The surface of a sample is decorated with copper to reveal the original Austrian grain boundary, which belongs to the technical field of metallographic sample preparation. Background technique [0002] The original austenite grain size of the steel can directly affect the microstructure change in the subsequent processing, thus affecting the strength, toughness and fatigue resistance of the steel and other performance indicators. Therefore, it is of great significance to accurately reflect the austenite grain size. Generally, the size of austenite grains is indirectly reflected by the method of etching austenite grain boundaries. Therefore, a good etching effect is essential for the study and calculation of the austenite grain size. However, since the original austenite is the high-temperature phase of steel...

AI Technical Summary

Problems solved by technology

However, because martensitic heat-resistant steel contains high alloying elements and has strong corrosion resistance and oxidation resistance, it is difficult to clearly display the prior austenite grain boundaries by traditional methods.

In addition, the room temperature structure of martensitic heat-resistant steel is mainly martensite structure, so that when the original austenite grain boundary is etched, the martensite structure morphology is also easily etched out, resulting in the identification of original austenite. Increased difficulty at tenite grain boundaries hinders assessment of prior-austenite grain size

In addition, picric acid itself has a low flash point and is easy to explode. If it is inhaled or touches the skin during the experiment, it will cause contact dermatitis or other chronic poisoning, endangering production safety and life and health.

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