采用宏观分析、金相检验、断口宏观及微观分析以及能谱分析等方法, 对某炼油厂裂化车间4台热交换器不锈钢管束先后发生大面积断裂的性质及原因进行了分析。结果表明: 该热交换器管束断裂是由在交变载荷和腐蚀介质作用下发生的由外向内的腐蚀疲劳开裂引起的; 腐蚀疲劳裂纹起始于管外壁的点蚀坑等应力集中处, 促进腐蚀疲劳裂纹扩展的管束外部介质主要是Cl-和H2S; 裂纹先以腐蚀疲劳开裂方式扩展, 而后又呈典型的应力腐蚀开裂方式继续扩展, 当应力腐蚀裂纹扩展达到管束断裂强度时便发生断裂。最后提出了预防管束断裂的措施及建议。

The nature and cause of massive fracture of stainless steel tube bundles of four heat exchangers of a petrochemical oil refinery work were analyzed by means of macroscopic examination, metallographic examination, fracture macro and micro analysis and energy spectrum analysis. The results show that the fracture of the stainless steel tube bundles was caused by corrosion fatigue cracking from outer wall to inner wall under the action of alternating load and corrosive medium, the corrosion fatigue cracks started from the outer wall corrosion pits, and Cl- and H2S in outside medium of the stainless steel tube bundles accelerated the propagation of the cracks. The cracks first propagated in corrosion fatigue mode, then continued to propagate in stress corrosion mode, and finally fracture happened when the crack propagation reached to fracture strength of the tube bundles. At last, measures and suggestions to prevent fracture were put forward.