Method used for testing residual stress in welding heat affected zone

Abstract

The invention relates to the field of material mechanical property characterization, and in particular relates to a method used for testing residual stress in a welding heat affected zone. The methodcomprises the steps that different press-in displacements h are loaded in a welding sample base zone to acquire corresponding press-in force F, and corresponding contact stiffness S is acquired at theinitial phase of unloading; according to the curve of the press-in force F and the press-in displacements h, curvature K1 is acquired; curvature K2 is acquired according to the curve of the contact stiffness S and the press-in displacements h; the set press-in displacement hx is loaded in the welding sample base zone to acquire the average press-in force F0 of the welding sample base zone; the set press-in displacement hx is loaded in the welding sample welding heat affected zone to acquire the press-in force FHAZ of the welding sample heat affected zone; and the welding residual stress of the welding sample heat affected zone is acquired. According to the method, a welding seam is prevented from being damaged; the test application range is expanded; the problem of inaccurate contact area calculation caused by the wear of an indenter is avoided; the problem of inaccurate contact area caused by the stacking effect is avoided; and the testing accuracy is ensured.

Description

technical field [0001] The present application relates to the field of characterization of mechanical properties of materials, in particular to a method for testing residual stress in a welding heat-affected zone. Background technique [0002] Welding is a process in which two or more materials of the same or different materials are connected together through the bonding and diffusion between atoms or molecules. Specifically, the workpiece and the solder are melted to form a molten area, and the molten pool is cooled and solidified to form a gap between materials. Connection. During welding, due to the temperature gradient generated inside the material during the heating or cooling process, residual stress will be generated in different micro-areas of the welding interface, and the welding residual stress will affect the fatigue strength, stress corrosion, cracking, deformation and reliability of the component. Therefore, testing the residual stress in the welding area has ...

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Problems solved by technology

Among them, the drilling method is specifically to drill a small hole on the component with residual stress, so that the corresponding displacement and strain will be generated in the zero zone of the small hole due to the release of part of the residual stress to test the residual stress; the peeling method is to start from the surface of the component Using methods such as cutting or corrosion to peel off the component layer by layer to release the residual stress in the component and test the residual stress; the cutting method is to cut grooves on the surface of the component to release the residual stress in the groove area, measure its strain and The method of obtaining the residual stress here; it can be seen from the above that the destructive testing is destructive to the weld, and the measurement accuracy is easily affected by external factors. In addition, the destructive testing cannot measure the thermal influence of the weld at the micro scale Residual stresses produced when zone material occurs

The X-ray diffraction method of non-destructive testing has high requirements on the surface of the welded sample, and can only be tested at a surface depth of about 30 μm, and has certain restrictions on the size and shape of the welded sample. The ultrasonic testing method is suitable for testing the three-dimensional residual stress of large components , the reliability of the residual stress test for the thermal influence of the welded joint is poor. It can be seen from the above that the scope of application of non-destructive testing is small and the test reliability is poor

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