高压内缸服役期裂纹产生原因分析及预防

Cause Analysis and Prevention of Crack in HP Inner Cylinder During Service

采用电子显微镜和XRD能谱分析等方法,对高压内缸在服役期间产生裂纹的原因进行分析。结果表明:晶间疏松、晶界上存在的非金属夹杂物是裂纹产生的主要原因,同时无损检测工艺不合理也造成了裂纹未检出。通过改善R角处的补缩条件、提高脱碳量到0.3%~0.4%,能够避免裂纹的产生;采用10 mm×10 mm的斜探头,并把扫查灵敏度提高到?3 mm+12 dB,确保检测出R角区域的缺陷。

the causes of crack in HP inner casing during service were analyzed by means of metallographic structure and X-RD energy spectrum analysis. The results showed that the cracks were mainly caused by intergranular porosity and non-metallic inclusion on grain boundary, and the cracks were not detected because of unreasonable nondestructive testing technology. The crack could be avoided by improving the feeding condition at R Angle and increasing the decarburization amount to 0.3%~0.4%. The defects in r-angle area could be detected by using a 10 mm×10 mm oblique probe and increasing the scanning sensitivity to ?3 mm+12 dB.