The grain boundary character distributions of TP347H stainless steel after different thermo-mechanical processes in terms of grain boundary engineering (GBE) were investigated by EBSD. DL-EPR and electrolytic oxalic acid etch tests were carried out to evaluate the improvement of GBE treatment on intergranular corrosion. The low-Σ CSL grain boundary proportion of the TP347H can be increased to about 90% through a single-step thermo-mechanical treatment consisted of a slight tensile deformation (3%) and subsequent annealing process at 1150°C for 1 h. Compared with conventional TP347H, the optimum GBE microstructure suppressed intergranular corrosion due to the high proportion of low-Σ CSL grain boundaries, particularly the twin (Σ3) boundaries which is almost immune to intergranular corrosion.

通过EBSD研究了TP347H不锈钢在晶界工程（GBE）方面经过不同热机械工艺后的晶界特征分布。进行了 DL-EPR 和电解草酸蚀刻测试，以评估 GBE 处理对晶间腐蚀的改进。TP347H 的低 Σ CSL 晶界比例可以通过单步热机械处理增加到约 90%，该处理包括轻微的拉伸变形 (3%) 和随后在 1150°C 下退火 1 小时的过程。与传统的 TP347H 相比，由于低 Σ CSL 晶界比例高，特别是几乎不受晶间腐蚀影响的孪晶 (Σ3) 晶界，最佳 GBE 显微组织抑制了晶间腐蚀。