15CrMo alloy steel pipe is a common alloy carbon steel, and the implementation standard is GB3087.

The microstructure of 15CrMo alloy steel pipe in normal supply state is ferrite plus pearlite. 15CrMo alloy steel pipe will produce pearlite spheroidization, alloying elements in solid solution and carbonization during long-term operation in the working temperature range of 500℃-550℃. The redistribution of objects and the change of carbide phase structure, the thermal strength and mechanical properties of 15CrMo alloy steel pipe will gradually decrease with the degree of pearlite spheroidization and solid solution depletion of alloying elements, so that the material gradually deteriorates. It even fails. Therefore, the degree of pearlite spheroidization in the structure of 15CrMo alloy steel pipe has been widely used as one of the important criteria for judging the usability of this type of steel for a long time.