Kane, Dalsimer, Kane, Sullivan and Kurucz
Precipitation hardening type stainless steel for spring
 Precipitation hardening type stainless steel comprising in % by weight, 0.03<C.ltoreq.0.08, 0.3.ltoreq.Si.ltoreq.2.5, Mn.ltoreq.4.0, 5.0.ltoreq.Ni.ltoreq.9.0, 12.0.ltoreq.Cr.ltoreq.17.0, 0.1.ltoreq.Cu.ltoreq.2.5, 0.2.ltoreq.Ti.ltoreq.1.0, and Al.ltoreq.1.0, the balance being Fe and impurities, the elements being further adjusted so that EQU A'=17.times.(C/Ti)+0.70.times.(Mn)+1.times.(Ni)+0.60.times.(Cr)+0.76.times. (Cu)-0.63.times.(Al)+20.871 is less than 42.0, ##EQU1## is not more than 2.7, and EQU .DELTA.Hv=205.times.[Ti-3.times.(C+N)]+205.times.[Al-2.times.(N)]+57.5.time s.(Si)+20.5.times.(Cu)+20 is within the range between 120 and 210, said steel as solution treated and optionally slightly cold worked having a substantial martencite structure. The steel has a good mechanical workability before aging, and when age hardened, it develops improved hardness and toughness as well as an isotropic and improved spring performance. 
Nisshin Steel Co., Ltd.
C
C22C
inventional
Sadao Kazuo Masahiro Teruyoshi
Hirotsu Hoshino Nishimura Iida