法兰用低铬超纯铁素体不锈钢开裂失效分析  

Cracking failure analysis of low-chromium ultrapure ferritic stainless steel for flange

作　　者：王志军[1] 齐江涛 WANG Zhijun;QI Jiangtao(Manufacturing Department,Shanxi Taiyuan Stainless Steel Co.,Ltd.,Taiyuan 030033,China)

机构地区：[1]山西太钢不锈钢股份有限公司制造部,山西太原030033

出　　处：《物理测试》2023年第4期49-52,共4页Physics Examination and Testing

摘　　要：低铬超纯铁素体不锈钢是法兰用钢的主要产品之一,对冲压法兰检验发现其端部有无规律的开裂缺陷,开裂发生在厚度方向的端面或单面起贯穿厚度方向。对法兰开裂处取20 mm×20 mm试样,利用X荧光能谱仪测定试样的化学成分;并对试样与轧制方向垂直截面进行打磨抛光,经FeC1_(3)+HC1混合酸溶液侵蚀后,利用光学显微镜(OM)观察组织形貌,最后利用扫描电镜(SEM)对试样进行析出物分析。经分析认为:在高温下退火时间过长,造成低铬超纯铁素体不锈钢基体晶内和晶界析出大量硬而脆的颗粒状金属间化合物(Fe_(2)Ti和Fe_(3)P),并沿厚度方向呈不规则带状分布,这些金属间化合物的析出,特别是P元素的冷脆效应引起的局部应力集中增加,导致法兰冷加工局部开裂。Low-chromium ultrapure ferritic stainless steel is one of the main products of flange steel.Some irregular crack defects were observed in the end of the stamped flange during inspection.The cracks occurred at the end face or single face in the thickness direction.A sample with dimension of 20 mm×20 mm was sampled from the cracking part of flange,and the chemical composition was determined by X-ray fluorescence spectrometer.The section perpendicular to the rolling direction of the sample was polished and etched by FeCl_(3)+HCl mixed acid solution.The microstructure and morphology were observed by optical microscope(OM),and the precipitated phases of sample were analyzed by scanning electron microscope(SEM).The analysis showed that the annealing time at high temperature was too long,resulting in the precipitation of a large number of hard and brittle granular intermetallic compounds(Fe_(2)Ti and Fe_(3)P)in the crystal and grain boundary of the low-chromium ultrapure ferritic stainless-steel matrix.These precipitated phases were irregularly distributed in the form of strips along the thickness direction.The precipitation of these intermetallic compounds,especially the cold brittleness effect of P element,caused the increase of local stress concentration,leading to local cracking during cold working of flanges.

关 键 词：铁素体不锈钢 法兰 开裂 P元素 

分 类 号：TG142.71[一般工业技术—材料科学与工程]