Method for testing subarea strain in low-cycle fatigue process of non-uniform structure welding joint

Abstract

The invention provides a method for testing subarea strain in the low-cycle fatigue process of a non-uniform structure welding joint. The method comprises the following steps: under the condition of setting strain values, a specimen is subjected to low-cycle fatigue performance testing, corrosion of the fractured specimen is observed, the fracture position is judged, and the strain fatigue life and material properties of the specimen are analyzed; an original position is marked on the same alternative specimen through a microhardness point; the marked specimen is subjected to static stretch testing; the specimen subjected to static stretch testing is subjected to surface corrosion, a subarea corresponding to the hardness mark point is found out, and the plasticity strain capacity generatedby the structure subareas is analyzed; the plasticity strain and total strain which are obtained during low-cycle fatigue testing of all the structure subareas of the specimen are corrected, and theactual strain of all the structure subareas is obtained; according to the actual strain of all the structure subareas and the fracture position of the specimen, the actual strain and the life of the fracture position are calculated; and the different strain values are set, the steps are repeated, and the actual strain-life relation is obtained.

Description

technical field [0001] The invention relates to the field of low-cycle fatigue testing of non-uniform structures of welded joints, in particular to a method for testing zoned strains in the process of low-cycle fatigue of non-uniform welded joints. Background technique [0002] In the current low-cycle fatigue test standard GB-T 15248-2008 "Metallic Materials Axial Equal Amplitude Low-Cycle Fatigue Test Method", only clear requirements are put forward for the low-cycle fatigue performance test method of homogeneous materials. The low-cycle fatigue performance test of welded joints is also generally carried out with reference to this standard. For welded joints, especially thick plate welded joints, the entire test range is composed of the base metal, heat-affected zone and complex structures in the weld. Different structures lead to different hardness and strength in each sub-area. The low cycle fatigue performance test of welded joints is completed by controlling the strai...

AI Technical Summary

Problems solved by technology

The present invention can not only effectively predict the fatigue strength of vermicular graphite cast iron, but also may be applicable to gray cast iron and metal matrix composite materials. At the same time, it can significantly reduce the amount of experiments required for conventional fatigue strength measurement, and the test process is simpler and faster, which obviously saves time , Reduce the cost of manpower and material resources. This method does not correct the fatigue strain according to the material organization partition, and the accuracy of the obtained data needs to be further improved.

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