Method for judging sensitivity of reheat cracks in coarse grain area

Abstract

The invention discloses a method for judging the sensitivity of reheat cracks in a coarse grain area, and belongs to the technical field of welding evaluation. The method comprises the following steps: firstly, carrying out a thermal simulation experiment on a low-alloy heat-resistant steel sample according to an actual thermal cycle process of low-alloy heat-resistant steel welding to obtain a sample with a coarse grain region structure, then carrying out a creep experiment on the sample, applying a preset stress to the sample under the conditions of constant temperature and constant strain until the sample is broken, and determining the welding quality of the low-alloy heat-resistant steel according to a stress relaxation curve in the experiment process. Calculating a creep strain value, and finally establishing a relationship between the creep strain and the percentage reduction of area in combination with an evaluation index of a short-time creep fracture test, so as to establish an evaluation criterion for evaluating the reheat crack sensitivity of the low-alloy heat-resistant steel welding coarse grain region. The method solves the problems of large calculation error of the percentage reduction of area and inaccurate evaluation of the reheating crack sensitivity of the coarse grain area caused by inaccurate measurement of the sectional area of the sample after interruption of the evaluation experiment of the reheating crack sensitivity of the coarse grain area of the low-alloy heat-resistant steel.

Description

technical field [0001] The invention belongs to the technical field of evaluation of welded joints, and in particular relates to a method for evaluating the sensitivity of reheat cracks in a coarse-grained region. Background technique [0002] Alloy steel with a total mass fraction of alloying elements below 5% is generally called low-alloy heat-resistant steel, and its alloy series are: C-Mo, C-Cr-Mo, C-Cr-Mo-V-Nb, C-Mo-V , C-Cr-Mo-V, C-Mn-Mo-V, C-Mn-Ni-Mo and C-Cr-Mo-W-V-Ti-B, etc. In recent years, with the advent of low-alloy Mo steel, Cr-Mo steel, and Cr-Mo-V steel, low-alloy heat-resistant steel has been widely used in boilers, It has been widely used in the fields of pressure vessels and chemical equipment. Nevertheless, precipitation-strengthened low-alloy heat-resistant steel welded joints have obvious tendency to reheat cracks in long-term use under high temperature and high pressure, and they mainly occur in the coarse-grained region of the heat-affected zone. T...

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Problems solved by technology

[0004] In order to solve the above-mentioned defects in the prior art, the object of the present invention is to provide a method for judging the sensitivity of reheat cracks in the coarse-grained region, which solves the problem of reheating crack sensitivity evaluation in the coarse-grained region of low-alloy heat-resistant steel. Inaccurate measurement of the cross-sectional area of ​​the sample leads to a large error in the calculation of the reduction of area and inaccurate evaluation of the sensitivity to reheat cracks in the coarse-grained area

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