Cold work effct on thermal strength of 12Kh1MF steel bends

A study was made on the effect of cold metal working on the efficiency of 12Kh1MF steel tube joints at 540-565 deg. C operation temperature. It was established that hardening during cold bending resulted to sharp growth of strength and decrease of plasticity of stretched tube part; long-term strength decreases by 25%, longevity under cyclic loads deteriorates 1.5-2 times. High-temperature bend tempering at 700-740 deg. C adjusts strength and plasticity characteristics, approaching them to the values of these characteristics for straight tube sections