Abstract: In order to prolong the service life of 20Cr13 steel fertilizer extrusion roller, the hardness, microstructure, and acid corrosion resistance of the 20Cr13 stainless steel after vacuum quenching at different temperatures and tempering at 180 ℃ were studied using metallographic microscope, scanning electron microscope, and Rockwell hardness tester. The results show that when the specimen is quenched in a wide temperature range above Ac₁, a certain amount of martensite structure can be obtained to improve the hardness. As the quenching temperature increases, the austenitization becomes more complete and the alloying degree of the matrix becomes higher, and as the austenite grains gradually grow, the residual austenite increases. Therefore, the hardness of the steel first increases and then decreases after quenching and tempering, but the corrosion resistance improves with the increase of quenching temperature. At the same time, by changing the right angle of the inner hole line cutting keyway of the quenched roller to R0.5-R1, the probability of longitudinal cracks cracking along the bottom right angle of the keyway during use is effectively reduced. After quenching at 1050 ℃ and tempering at 180 ℃, the on-site use verification of the roller shows that obtaining a reasonable microstructure after quenching is more conducive to improving the wear and corrosion resistance of the roller than simply pursuing high hardness, greatly improving its service life. After improvement, the average lifespan of extruded fertilizer particles for each pair of rollers reaches 800-1000, which is more than twice the lifespan compared to that of 1000 ℃ quenched and 180 ℃ tempered rollers.

Key words: fertilizer extrusion roller, Cr13 stainless steel, vacuum quenching, retained austenite, wear corrosion, keyway fillet transition