Disclosed is a non-heat treated steel for soft niriding, which can provide forged parts exhibiting equal to or larger than the limit strain at which cracks occur in straightening by bending and equal to or larger than the fatigue strength when compared with the parts of conventional heat treated steel, such as S48C. The non-heat treated steel for soft nitriding consists essentially of, by weight, C: 0.2-0.6%, Si: 0.05-1.0%, Mn: 0.25-1.0%, S: 0.03-0.2%, Cr: up to 0.2%, sol-Al: up to 0.045%, Ti: 0.002-0.01%, N: 0.005-0.025%, and O: 0.001-0.005%; provided that the conditions, 0.12[Ti%]<[O%]<2.5[Ti%] and 0.04[N%]<[O%]<0.75[N%], are met; the balance being Fe and inevitable impurities; and the structure after hot forging being a mixed structure of ferrite and pearlite.

Se divulga un acero tratado no-calor para niriding suave, a el cual puede proporcionar la exhibición forjada de las piezas igual o más grande que la tensión del límite en a la cual las grietas ocurren en enderezarse doblándose e igual o más grande que la fuerza de la fatiga en comparación con las partes de acero tratado calor convencional, tales como S48C. El acero tratado no-calor para la nitruración suave consiste esencialmente en, al lado del peso, C: 0.2-0.6%, silicio: 0.05-1.0%, manganeso: 0.25-1.0%, S: 0.03-0.2%, cr: hasta 0.2%, solenoide-sol-Al: hasta 0.045%, ti: 0.002-0.01%, N: 0.005-0.025%, y O: 0.001-0.005%; a condición de que las condiciones, el 0.12[Ti%