A metallographic phase corrosive used for displaying a tempered sorbite tissue austenite crystal boundary and a corroding method

Abstract

The invention discloses a metallographic phase corrosive used for displaying a tempered sorbite tissue austenite crystal boundary and a corroding method. The metallographic phase corrosive comprises saturated picric acid, sodium dodecylbenzenesulfonate and alkanolamide, wherein the corrosive comprises 0.1-15 wt% of the sodium dodecylbenzenesulfonate and X wt% of the alkanolamide, with the balance being the saturated picric acid, wherein the X is any value between 0 and 1 with the 0 and the 1 being inclusive. The metallographic phase corrosive prepared by adopting a formula and through the preparing method can allow the tempered sorbite crystal boundary to be presented clearly and continuously and to be not influenced by tissues, and allows each crystal grain to be clearly observed, thus improving accuracy and precision of judgment. Corrosion is performed at room temperature, is free of heating, wide in corrosion time range, free of over-corrosion, economical, practical, convenient in operation, time-saving, labor-saving, and free of pollution.

Description

technical field [0001] The invention relates to an etchant and a corrosion method, in particular to an etchant and a corrosion method for displaying tempered sorbite structure austenite grain boundaries, and belongs to the technical field of metallographic analysis. Background technique [0002] Metal materials get different structures under different heat treatment states. The properties of materials often depend on the state of the structure. The size of the grain size is also a key factor affecting the performance. Therefore, in metallographic analysis, the evaluation of grain size has attracted much attention. Tempered sorbite refers to a composite structure in which fine-grained cementite is distributed in a ferrite matrix formed after martensite is tempered at a high temperature. Corrosion and evaluation of tempered sorbite grain size has always been a difficult problem in the industry. [0003] In the prior art, saturated picric acid solution or 4wt% nitric acid alc...

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Problems solved by technology

[0003] In the prior art, saturated picric acid solution or 4wt% nitric acid alcohol is often used to display the tempered sorbite grain size, and the corrosion results are shown in the attached figure 1 , attached figure 2 As shown, there are also reagents such as special detergent, but the effects are not good; in addition, the patent CN103454187A mentions the room temperature corrosion method with supersaturated picric acid and sodium dodecylbenzenesulfonate solution

[0004] However, the above method often faces four problems: 1) 80-100 ℃ hot etching, accompanied by high temperature danger, and short corrosion time, which can easily cause over-corrosion; secondly, hot etching usually cannot achieve the corrosion effect at one time, Multi-pass grinding and polishing are required, and the proficiency requirements for operators are relatively strict, and in many cases, the grain boundary display is not very obvious; 2) The microstructure after corrosion by nitric acid alcohol solution is obvious, which greatly affects the grain size. 3) The references of special detergents are mostly based on empirical methods, and there is no unified and clear statement on their specific components and efficacy; 4) Sodium dodecylbenzene sulfonate is volatile, and its content may change during the experiment. Decreasing, not quantifiable

[0005] Therefore, the corrosion of tempered sorbite grain boundaries has no recognized representative etchant and preparation and corrosion methods so far.

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