The poor machining characteristics of super duplex stainless steels (SDSS) affect the surface integrity as it induces tensile residual stress in the parts. When this machined part is exposed to hostile chloride conditions, it results in the stress corrosion crack (SCC) formation, thereby impacting their service life. To understand the cracking phenomenon involved, it is important to study the distinct characteristics of cracks formed in compliance with the machining (turning) process. This study focusses on studying the effects of machined surface integrity on the stress corrosion cracking of SDSS. Following machining, the specimens were subjected to SCC examination in the chloride condition at different immersion time of 1 h, 2 h, and 5 h. The testing was done in pursuant with ASTM G36 standard. The result indicated that major cracks generated along both parallel as well as the perpendicular direction of machining marks due to the high magnitude of biaxial tensile residual stress. With the increase in immersion time (5 h), new forms of crack and localized corrosion were noticed on the surface. At 1 h and 2 h, only the major cracks were evident, along with minor pit formation on the surface. But at 5 h, selective attack/selective leaching occurred on the turned surface along with the formation of network of cracks. Analysis of the transition pit/crack behaviour of revealed that different pits merge to form a detrimental crack with more intensity than the major cracks. The crack density continue to grow with immersion time of 5 h and also there is no evidence was observed on reduction of crack density. However, the quantification of crack density was not possible at 5 h due to the complex network of high density crack formation. The microstructure analysis revealed that the ferrite phase was more vulnerable to SCC than the austenite phase in chloride environment.

超级双相不锈钢（SDSS）较差的加工性能会影响表面完整性，因为它会在零件中引起拉伸残余应力。当该机械零件暴露于不利的氯化物条件下时，会导致应力腐蚀裂纹（SCC）的形成，从而影响其使用寿命。要了解所涉及的开裂现象，研究符合机加工（车削）过程而形成的裂纹的独特特征非常重要。这项研究的重点是研究机械加工表面完整性对SDSS应力腐蚀开裂的影响。加工后，将样品在氯化物条件下于1h，2h和5h的不同浸没时间进行SCC检查。该测试是根据ASTM G36标准进行的。结果表明，由于双轴拉伸残余应力的幅度较大，沿加工标记的平行和垂直方向均产生了大裂纹。随着浸泡时间（5小时）的增加，在表面上发现了新形式的裂纹和局部腐蚀。在1 h和2 h时，只有主要的裂纹是明显的，并且在表面上形成了较小的凹坑。但在5 h时，随着裂纹网络的形成，选择性腐蚀/选择性浸出发生在车削表面上。分析的过渡坑/裂纹行为表明，不同的坑合并形成了比主要裂纹强度更大的有害裂纹。随着5h的浸没时间，裂纹密度继续增长，并且也没有观察到裂纹密度降低的证据。然而，由于高密度裂纹形成的复杂网络，不可能在5 h量化裂纹密度。显微组织分析表明，在氯化物环境下，铁素体相比奥氏体相更易受SCC腐蚀。