液化裂纹敏感性评价试验方法综述

A Review of Test Methods for Evaluating on Liquation Cracking Susceptibility

在机械装备制造业中,由焊接缺陷引起的事故频发,焊接热裂纹是典型焊接缺陷之一。液化裂纹作为热裂纹的常见形态,是由于母材受焊接热作用或多道焊的前道焊缝金属受后续焊道再热作用,局部晶界液化而导致的裂纹,易引发金属结构失效及事故,客观评价和理解材料的液化裂纹敏感性尤为重要。目前已开发140多种试验方法用于评价金属材料焊件液化裂纹敏感性,其中热延性试验、程控平板拉伸试验等方法在压力容器、航天航空、石油化工等领域得到广泛应用。综述了其中适用性较广的几种方法,并总结了不同试验方法所采用的敏感性判据,主要包括温度区间和裂纹长度等。但是不同判据的适用条件有所差异,因此未来推进已有材料液化裂纹评价试验方法的优化以及判据结果的标准化研究尤为重要,这将有助于机械装备中液化裂纹的预测和防治,提高机械装备的使用寿命。

In the machinery equipment manufacturing industry,accidents caused by welding defects occur frequently.Welding hot crack is one of the typical welding defects.As common forms of hot cracks,liquation cracks can easily lead to metal structure failures and accidents.The objective evaluation and understanding of the liquation crack susceptibility of materials is particularly important.Liquation cracks are cracks caused by local grain boundary liquefaction due to the heat of the base metal or the reheating of the previous weld metal of the multi-pass weld.More than 140 test methods have been developed to evaluate the susceptibility of liquation crack in metal welding parts,among which thermal ductility test,programmierter verformungs test is widely used in pressure vessels,aerospace,petrochemical and other fields.In this paper,several kinds of widely-used method are reviewed,and the different test methods adopted by the susceptibility criterion have been discussed,which mainly includes temperature range and cracking length.However,the applicable conditions of different criteria are different,so it is particularly important to promote the optimization of liquation crack evaluation test of existing materials and the standardization of criterion results in the future,which will help to predict and prevent liquation cracking in machinery equipment and improve the service life of machinery and equipment.