核级不锈钢大尺寸应力腐蚀裂纹的制备技术研究

Investigation on the Preparation Technology of Large-size Stress Corrosion Cracks of Nuclear-grade Stainless Steel

采用316L奥氏体不锈钢小尺寸试样进行预研制,初步确定了预制大尺寸试样应力腐蚀裂纹的参数。结果表明:3.5%(质量分数)NaCl溶液,-1.2 V(相对于SCE)外加电位,降低应变速率,并延长极化作用时间有利于应力腐蚀的发生,且降低断后伸长率。在此基础上,100 kN保载24 d后,以0.5×10^(-6) s^(-1)应变速率进行慢应变速率试验,可在大尺寸试样上成功制得长度超过25 mm的裂纹,且大尺寸试样的断后伸长率仅为12%。

316 L austenitic stainless steel small-size sample was pre-developed,and the stress corrosion cracking parameters of prefabricated large-size sample was preliminarily determined.The results showed that 3.5%(mass fraction)NaCl solution,-1.2 V(vs.SCE)applied potential,reducing the strain rate and prolonging the polarization time were conducive to the occurrence of stress corrosion and reduced the elongation after fracture.On this basis,after a holding load of 100 kN for 24 d,a slow strain rate test was carried out at a strain rate of 0.5×10^(-6) s^(-1),and a crack with a length of more than 25 mm could be successfully produced on a large-size sample.And the elongation after fracture of the large size sample was only 12%.