API 5L X52Q:
"Q" usually stands for "quenched and tempered". This type of pipe is quenched and tempered during the manufacturing process. After quenching and tempering, the yield strength and tensile strength can better meet the high strength requirements.
The quenching and tempering process can refine the grains and improve the strength and toughness of the material. Its minimum yield strength can reach about 360MPa, and the tensile strength is about 460MPa. It can withstand large pressure and tension to a certain extent and performs well in high-pressure environments.
During welding, due to quenching and tempering, its welding process needs to consider the performance changes of the heat-affected zone. During welding, the welding heat input needs to be strictly controlled to avoid the decrease in strength and toughness due to the change of the structure of the heat-affected zone.
API 5L X52N: "N" stands for "normalized". This means that the pipe has been normalized. In terms of chemical composition, it must also meet the basic composition range of API 5L X52.
The yield strength and tensile strength after normalizing can also meet API 5L X52 The standard of normalizing, but its strength characteristics may be slightly different from those of quenching and tempering. Normalizing is mainly to improve the organizational structure of the material and make it more uniform.
The welding performance in the normalized state is relatively easy to control. Because the organizational structure after normalizing is more uniform, the performance change of the heat affected zone during welding is relatively small. However, it is still necessary to operate according to the welding process regulations and select appropriate welding materials and parameters to ensure the welding quality.
API 5L X52 Hochtemperatur-Leitungsrohr
