温度、水化学环境及冷加工程度对321不锈钢应力腐蚀裂纹扩展速率的影响

Effect of Temperature,Water-chemical Environment and Cold Work on Stress Corrosion Crack Growth Rate of 321SS

压水堆(PWR)一回路水的水化学环境、温度及冷加工程度对一回路管道的应力腐蚀开裂(SCC)具有重要影响,因此研究不同因素对一回路管道材料应力腐蚀开裂的影响具有重要意义。本文采用恒应力场强度因子法研究了不同温度、水化学环境及不同冷加工程度对321不锈钢(321SS)在高温高压水中应力腐蚀裂纹扩展速率(SCCGR)的影响,并研究这些因素的协同作用。研究结果表明,在B-Li及B-Li-O_(2)环境中,随温度升高材料的SCCGR先增大后减小,而在B-Li-O_(2)-Cl^(-)环境中,随温度升高SCCGR不断增大;水中溶氧(DO)及Cl^(-)对材料的SCCGR有协同促进作用,且O_(2)的加入对SCCGR的影响较Cl^(-)大;在B-Li环境中,冷加工对材料的SCCGR影响较小,而在腐蚀性环境(B-Li-O_(2)、B-Li-O_(2)-Cl^(-))中冷加工对材料的SCCGR影响较大,且腐蚀性环境越强,冷加工对SCCGR影响越大。经实验表明,温度、水化学环境及冷加工程度对321SS应力腐蚀裂纹扩展的影响具有协同作用。

The water-chemical environment,temperature,and cold work have an important influence on the stress corrosion cracking(SCC)of the primary loop pipe of pressurized water reactor(PWR).Therefore,it is of great significance to study the influence of different factors on the SCC of the primary loop pipe.The effect of temperature,water-chemical environment,and cold work on stress corrosion crack growth rate(SCCGR)of 321 stainless steel(321SS)with experiment of constant stress field intensity factor was studied.And the synergistic effect of these factors on SCCGR of 321SS was also studied.It is found that with the increase of temperature,the SCCGR of the materials increases first and then decreases in the B-Li and B-Li-O_(2) environments.But SCCGR increases with the temperature in the B-Li-O_(2)-Cl^(-)environment.Dissolved oxygen(DO)and Cl-have synergistic effect on the SCCGR,and the effect of O_(2) on SCCGR is greater than that of Cl^(-).In B-Li environment,cold work has little effect on SCCGR of the material.However,in corrosive environments(B-Li-O_(2),B-Li-O_(2)-Cl^(-)),cold work has a greater influence on SCCGR of materials,and the stronger the corrosive environment,the greater the impact of cold work on SCCGR.The experimental results show that water-chemical environment,temperature,and cold work have synergistic effect on the stress corrosion crack growth of 321SS.