Influence of Quenching On-line on Properties of X70 Steel for Sour Service Seamless Pipe

It is always hard to resolve the low strength problem of grade X70 sour service seamless steel pipes with large diameter and heavy thickness using traditional quenching off-line, when low carbon and low alloy steel had been used to produce the pipes. In this paper, the influence of quenching on-line on the property and microstructure of such a product was reported. It was shown that the strength can be improved and good toughness can be obtained. At the same time, production cost may be reduced.