Method for testing thickness of alpha pollution layer

Abstract

The invention relates to a method for testing the thickness of an alpha pollution layer, and belongs to the technical field of surface quality detection of titanium and titanium alloy castings. The hardness of the alpha pollution layer is relatively high, so that after a base material penetrates through the alpha pollution layer, the hardness of the base material can be reduced. By utilizing the characteristic, the outer surfaces of the titanium and titanium alloy castings are subjected to hardness testing from the surface to the interior of the base material through the alpha pollution layer,and hardness values of a plurality of test points are obtained; and the thickness of the alpha pollution layer is calculated by analyzing the hardness values of the test points. The method disclosedby the invention can be used for more intuitively, rapidly, conveniently, efficiently and accurately calculating the thickness of the alpha pollution layer.

Description

technical field [0001] The invention relates to a method for testing the thickness of an alpha pollution layer, belonging to the technical field of surface quality detection of titanium and titanium alloy castings. Background technique [0002] Titanium and titanium alloys are important structural metals that have been gradually developed in recent years. They have excellent properties such as high strength, good corrosion resistance, and high heat resistance, and are widely used in aviation, aerospace, and military fields. However, in the process of precision casting of titanium alloys, titanium and titanium alloys have high melting point, large heat capacity, small thermal conductivity and active chemical properties, which make them highly chemically active in a high-temperature molten state and are very easy to contact with The interfacial chemical reaction of the casting material will form an alpha pollution layer on the surface of the casting. The pollution layer has h...

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Problems solved by technology

[0003] In the prior art, there are patent literature reports on methods for measuring the thickness of the α-contaminated layer of titanium and titanium alloy castings. For example, the patent literature with the publication number CN107328788A discloses the average thickness of the α-contaminated layer of a cylindrical titanium alloy sample. This method uses the different characteristics of the fracture surface of the α-contaminated layer and the substrate, and uses the fracture method to directly measure the area content of the α-contaminated layer without grinding and dyeing the metallographic sample, and then the circle area calculation formula and the α-contaminated layer The average thickness is indirectly calculated from the layer area content relationship; the disadvantage of this method is that it is only applicable to cylindrical samples, and can only indirectly calculate the average thickness of the α-contaminated layer, and cannot test the thickness of the α-contaminated layer at a specified point

The patent document whose publication number is CN107328788A discloses a method for measuring the depth of the contamination layer on the surface of a cast titanium alloy workpiece. The mixed solution corrodes the surface, and cleans the surface with clean water; blows the surface of the cast titanium alloy workpiece dry; then takes the cast titanium alloy workpiece out of the fixture, observes the surface with an optical microscope and takes pictures; according to the photographed Photo measures the depth of the surface contamination layer; the disadvantage of this method is that the pretreatment process is more complicated

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