Measuring method for real stress-strain curve of metal welding structure

Abstract

A measuring method for a real stress-strain curve of a metal welding structure comprises the steps: firstly, measuring a real stress-strain curve of a notch tensile test, wherein a real fracture strain at a maximum load is a strain hardening index of a metal of a to-be-measured position; calculating real stress-strain curves of notch tensile samples by finite element calculating software, to obtain the real stress-strain curves of the notch tensile samples with different notch sizes, fitting and establishing the relationship between the notch size and a geometric factor, and establishing a geometric factor expression containing the notch size and the real fracture strain at the maximum load and other influence factors; according to a load separation theory and the obtained relational expression and expression, the real stress-strain curve of the metal of the to-be-measured region of the metal welding structure is obtained. Through the small-size notch tensile test and a series of established relationships, the locality of the to-be-measured material region is accurately transmitted to a whole single-region material.

Description

technical field [0001] The invention belongs to the technical field of materials, and in particular relates to a method for measuring the true stress-strain curve of a metal welded structure. Background technique [0002] For welded structural parts, the material is heterogeneous in nature, and the mechanical properties of the base metal, weld, and heat-affected zone are different. The full true stress of each material area is required for fracture evaluation of welded structures. true strain curve. Due to the economy and convenience, the transverse tensile test of welded joints is widely used in the evaluation of weld quality. For example, the occurrence of fracture failure in the base metal represents good weld quality, while the occurrence of fracture failure in the weld metal or the heat-affected zone indicates that the weld Seam quality is poor. The transverse tensile test of welded joints can record the relationship between load and axial elongation. Obviously, this ...

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Problems solved by technology

The transverse tensile test of welded joints can record the relationship between load and axial elongation. Obviously, this curve cannot be used for failure assessment of welded structures, because the curve depends largely on the initial measurement of the gauge length of the sample and the sampling method , the position of the necking and the termination zone, etc., and the test results of this test characterize the overall quality of the three different material regions of the welded joint, and cannot accurately measure the stress-strain curve of each region, and cannot give a clue to the fracture evaluation of the welded structure. to provide effective material performance information

In the transverse tensile test of welded joints, strain gauges can be pasted on different material regions in the sample or optical measurement can be used to measure the real strain of the material, but these methods have obvious limitations, and it is difficult to directly convert the surface strain and deformation into the material. Full stress-strain relationship

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