Abstract: A thick-wall L80-13Cr seamless steel pipe was austenitized at 1000 ℃ for 150 min, and then cooled by air, water immersion and water spray respectively, followed by tempering at 710 ℃ for 200 min. The effects of the quenching media on the microstructure and mechanical properties of the steel pipe were studied by means of microstructure observation and mechanical property testing. The results show that the cooling performance of the three quenching media from high to low are water immersion cooling process, water spray cooling process, and air cooling process; the strength and impact absorbed energy are increased with the acceleration of cooling rate. After quenching of the steel pipe, the average impact absorbed energy and the tensile strength under air cooling are 23.67 J and 764 MPa respectively, that under water spray cooling are 42.00 J and 787 MPa respectively, and that under water immersion cooling are 50.33 J and 800 MPa respectively. However, the process of water immersion cooling is prone to quenching cracking and resulting in the scrapping of the material. The water spray cooling produces fine and uniform microstructure and excellent performance, so it is the most suitable quenching cooling method.

Key words: thick-wall L80-13Cr seamless steel pipe, quenching media, microstructure, mechanical properties