在TP347H不锈钢大小头管生产过程中表面出现了环向裂纹:通过对钢管的化学成分、硬度、夹杂物、晶粒度、显微组织、裂纹处微观形貌和能谱微区成分等进行了分析,找出了裂纹产生的原因.结果表明:不锈钢管的表面裂纹是应力腐蚀裂纹:不锈钢管在成型过程中产生残余应力是裂纹产生的内因,在酸洗过程中带来的氯离子是裂纹产生的外因,晶界碳化铬的析出加剧了应力腐蚀开裂.

Circumferential annular cracks generated during manufacture were found on the surface of TP347H stainless steel tube.The cracking cause was analyzed by some experimental methods such as chemical composition analysis,hardness check,inclusion analysis,grain size test,microstructure and crack morphology observation,and energy spectrum analysis.The results show that the surface cracks of the stainless steel tube were stress corrosion cracks.The internal cause for the cracks were the residual stress from the drawing process of the stainless steel tapered tube and the external cause was the chloride ions generated in the course of the acid pickling.The precipitation of chromium carbide at the grain boundaries accelerated the stress corrosion crack.