a non - heat treated soft - nitrided steel part respective contents of c , si , mn , p , cr , ti , v , n , al , pb , s and ca of which are in specific ranges and which satisfies the following formulas to . this part can be produced in a process of hot working , machining and soft - nitriding without any prior heat treatment , and has superior properties such as high fatigue strength and wear resistance . fn1 =− 141 . 5 − 19 . 6 + 1280 + 95 . 6 ≦ 60 fn2 =− 103 . 8 + 59 . 1 + 850 . 4 + 360 . 9 ≧ 350 fn3 =− 13 . 4 − 3 . 45 + 112 . 7 + 13 . 2 ≧ 7