The addition of an appropriate amount of nitrogen to F51 stainless steel not only improves the pitting and SCC resistance of the steel, but also does not significantly reduce the plastic toughness due to the severe coarsening of the grains in the heat affected zone of the weld, and is also insensitive to welding hot cracks. Therefore, the corrosion resistance and mechanical properties of the heat affected zone of the weld are improved. The SCC resistance, wear corrosion resistance and corrosion fatigue resistance in many media are better than those of austenitic stainless steel [1-5]. In particular, the SCC resistance in a Cl-containing environment is particularly excellent [6]. The H2S SCC resistance is better than that of S30403 and S31603.Steel Pipe Cap is also called Steel Plug, it usually welded to the pipe end or mounted on the external thread of the pipe end to cover the pipe fittings. To close the pipeline so the function is the same as the pipe plug.(You can also to use a blind plate to close the pipeline, differently the blind plate is detachable and the welded steel cap is not removable. The cap includes a convex cap, a conical shell, a variable diameter section, a flat cover and a constricted opening.)