Supplanting some carbon in martensitic hardened steels by nitrogen is a new development.[when?] The restricted dissolvability of nitrogen is expanded by the pressing factor electroslag refining (PESR) measure, in which liquefying is done under high nitrogen tension. Steel containing up to 0.4% nitrogen has been accomplished, prompting higher hardness and strength and higher consumption opposition. As PESR is costly, lower yet huge nitrogen substance have been accomplished utilizing the standard argon oxygen decarburization (AOD) measure
