Variation microstructure and properties of X80 pipeline steel in the rapid induction tempering process

A self-developed electromagnetic induction-heating device was used to investigate the variation in the microstructure and properties of X80 pipeline steel in the rapid induction tempering process at different process parameters. The effects of the tempering condition on toughness,microstructure,size and distribution of precipitates of X80 pipeline steel were observed using a metallographic microscopy and scanning electron microscopy.Compared with the samples prepared via traditional tempering techniques,results showthat the samples prepared via rapid induction tempering had improved performances. When the heating temperature is 590 ℃,at a holding time of90 s,it was found that acicular ferrite was refined,carbonite precipitation was small,and precipitates were evenly distributed in the matrix. The low-temperature impact energy,also known as the impact absorption energy,at- 40 ℃ was found to be 430. 5 J for the rapid induction tempering samples and 323. 2 J for the traditionally tempered sample. The low-temperature impact energy at- 60 ℃ was found to be 351. 3 J for the rapid induction tempered sample and 312. 1 J for the tradition tempering sample.