Researches on the Fatigue Crack Propagation of Pipeline Steel

Researches and industrialization of pipeline steel fatigue crack propagation are summarized, especially the X60 and X70 pipeline steel after mechanical damage and in the synthetic soil solution. The results show that the fatigue crack propagation of the pipeline steel has the similar law after mechanical damage or in the synthetic soil solution. It is very clearly that the fatigue crack propagation is deeply depending on the ΔK, and there are all have threshold characters. The mechanical damage and the synthetic soil solution can increase the fatigue crack propagation rate, decrease the fatigue crack propagation threshold ΔKth, accelerate crack propagation rate and shorten the service life of the pipe.