Effect of Trace Elements Al and N on Quenching Microstructure and Hardenability of SWRCH35K Steel

SWRCH35K hot-rolled wire rods with different content (microscale) of Al and N were produced by converter smelting-LF furnace refining-continuous casting-controlled rolling-controlled cooling process. The quenching microstructure and hardenability of SWRCH35K steel were investigated by quenching and Jominy test. The results show that the microstructure of SWRCH35K steel after quenching was martensite and troostite. Martensite content decreased with the increase of N content after quenching and the hardenability of steel degraded when Al content was almost the same. Martensite content decreased with the increase of Al content after quenching and the hardenability of steel degraded when N content was almost the same. AlN or carbonitride formed by Al and N elements promoted grain refinement and prevented the formation of martensite.