晶间腐蚀损伤材料的强度估计方法

An Estimate Method for Tensile Strength of Intergranular Corrosion Damaged Materials

不锈钢焊接可能引起焊缝热影响区敏化,容易引发贫铬效应导致应力腐蚀开裂。产生晶间腐蚀损伤后,材料在细观尺度上不再是均匀的,引起应力重新分布,对材料有效性能产生较大影响。根据这种腐蚀损伤分布不均匀性特点,定义了晶界腐蚀均匀度h对腐蚀损伤分布的不均匀性进行量化,并提出了利用图像处理确定h的方法。根据晶界腐蚀后的细观组织图,将产生晶间腐蚀损伤的材料分为富含腐蚀损伤的晶界等效基体相和不含腐蚀损伤的晶粒等效颗粒相,利用相互作用直推估计法(IDD)研究了材料强度随均匀度h的变化关系。理论分析结果表明,均匀度h对材料强度有较大影响,腐蚀损伤的均匀度越小,材料强度越低,并且在均匀度低于0.2时造成强度的剧烈降低。

The overheated zone around the weld line is easily sensitized by the high temperature of metal welding, and it tends to cause stress corrosion cracking for the poor chruomium effects in the zone. After the intergranular corrosion damage generated, the base-metal was not uniform ever in micro-scale. Stress in the metal redistributed, and this redistributing caused the metal equivalent property changed. Parameter h was defined to quantize the uniformity of intergranular corrosion damage, and an image processing method was introduced to confirm the parameter h. According to the image processing results, damaged material was divided to two parts, namely the effective matrix phase of grain boundary and the effective grain phase of grains. Based on interact direct derivative (IDD) estimate, the relationship between tensile strength and uniformity was analyzed. Results indicated that uniformity h has significant influence to material tensile strength, and the tensile strength reduces with uniformity decreasing, especially when the uniformity h is lower than 0.2.