某医院矩形脉动真空灭菌器内腔发生开裂事故，通过宏观分析、金相检验和光谱分析等方法，结合工作介质，对内腔开裂的原因进行了分析。结果表明：灭菌器内腔与加强筋不连续焊接处存在焊接残余应力，且靠近内腔弯折处存在局部应力集中现象；灭菌器内腔的工作介质中含有氯离子，而氯离子水溶液是300系列不锈钢发生应力腐蚀开裂的敏感介质。灭菌器内腔在焊接残余应力、含氯离子介质等因素的综合作用下发生起始于靠近内腔弯折的焊接起始处的应力腐蚀开裂。

The inner cavity of rectangular pulsating vacuum sterilizer in a hospital cracked. The causes of cracking on inner cavity were analyzed by means of macro analysis, metallographic examination and spectrum analysis, combined with working medium. The results show that the welding residual stress existed in the discontinuous welding joint between the inner cavity and the reinforcing rib, and the local stress concentration phenomenon existed near the bending part of inner cavity. The working medium of the sterilizer contained chloride ion, and chloride ions aqueous solution was the sensitive medium for stress corrosion cracking of 300 series stainless steel. Under the combined effect of welding residual stress and chloride ion medium, the stress corrosion cracking of the inner cavity of sterilizer started from the welding beginning near the bending of inner cavity.