Tendency of corner welded joints to brittle fracture under creep conditions

Long-term strength and ductility of welded joints of dissimilar steels applied in heat exchangers have been investigated. 12Kh1MF and 12Kh2MFSR steels as well as steel-20 have been tested at 600 deg C under bending conditions. Suggested is a sample model which permits to reproduce under laboratory conditions fractures occuring during operation. It is established that one of the main reasons of weld fracture in 12Kh1MF and 12Kh2MFSR steel joints is insufficient ductility caused by deviations from optimum conditions of heat treatment after welding. Welded joints of 20 and 12Kh1MF steels fractured about weld irrespective to heat treatment. Recommendations on using welding electrodes for joints of the above type are presented