| 摘要 |
It is devised to further enhance strength and straightening ability of a nitrocarburized raw material for crankshafts. A nitrocarburized raw material for crankshafts is formed so as to have a composition composed of C, Si, Mn, Cu, Ni, Cr, V, S, s-Al, Ca and N in prescribed % by mass, with the balance being Fe and inevitable impurities and having a structure of ferrite + pearlite; after smelting a steel having the foregoing composition, hot forging is performed; thereafter, a normalizing treatment is applied to the subject hot forged material at a treatment temperature in the range of from 780°C to 850°C; and straightening process for correcting bending to be caused due to the nitrocarburizing treatment is later applied. |
