High-carbon steel wire rod tissue grain size grading method

Abstract

The invention discloses a high-carbon steel wire rod tissue grain size grading method. The method can finish high-carbon steel wire rod tissue grain size grading by the steps of manufacturing a sample, mechanically treating, chemically treating, observing and assessing and displaying results. The method disclosed by the invention achieves high-carbon steel wire rod tissue grain size grading by assessing the tissue grain size, namely the microscopy tissue morphology size. According to the method disclosed by the invention, an identical corrosion degree on the surface of a test sample is achieved by limiting nitric acid alcohol concentration and corrosion time; compared with a standard atlas, assessment errors can be reduced. According to the method disclosed by the invention, a supplementary effect among multiples is achieved by respectively grading tissue grade sizes under 100 times and 500 times. According to the method disclosed by the invention, four view fields and a core view field are chosen from on a detection ring of one fourth of the diameter of a high-carbon steel wire rod through observing positions and view field regulations; the choice of the observing positions and the view fields can reflect the tissue grain size situation of the whole cross section; thus, the obtained assessment results has strong representativeness, reality and validity.

Description

technical field [0001] The invention relates to a grading method, in particular to a method for grading the grain size of a high-carbon steel wire rod. Background technique [0002] The high-carbon steel wire rod is hot-rolled after the steel billet is austenitized by heating, and then cooled by air cooling to obtain a sorbite structure that is easy to draw. The actual grain size is obtained after direct erosion with nitric acid alcohol solution. The grain boundaries of this high-carbon steel structure are fine, and the sorbite structure is composed of ferrite and cementite alternately, and the sorbite structure Under the optical microscope at 500 times, it is impossible to distinguish the structure of ferrite and cementite alternately distributed, and the original austenite grain boundary is not easy to be corroded. It is impossible to find out where the grain boundary of the organization group is. Although this method is simple, we cannot use the GB / T 6394-2002 grain size...

AI Technical Summary

Problems solved by technology

[0005] In order to accurately evaluate the grain size of high-carbon steel wire rods by using the grain size standard rating chart, only the austenite grain size can be evaluated, but the actual grain size cannot be evaluated.

To evaluate the austenite grain size of high-carbon steel wire rod, heat treatment must be carried out first, such as direct hardening method, this method is not only cumbersome but also if the temperature and holding time are not handled properly during heat treatment, it will cause austenite Unfavorable factors such as coarse grains or insufficient austenite will further affect the result evaluation

Moreover, the austenite grain size is evaluated instead of the actual grain size, which cannot directly reflect the pros and cons of the production process, so it cannot guide the improvement of the production process

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