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. The socket elbow is a type of high-pressure fitting used for pipeline connections, mainly formed by press-forging round steel or steel ingots into blanks, which are then machined on a lathe. Due to its unique structural design, this elbow can withstand high pressures and is widely used in various high-pressure pipeline systems.The socket elbow is part of the forged socket series of pipe fittings, and its connection method is a socket type, meaning one end is inserted into the socket of the other end, and tight connections are achieved through threads or other fastening methods. This connection method is not only easy to operate but also has good sealing performance, making it suitable for the transport of various media.