STEEL SHEET FOR SOFT-NITRIDING AND METHOD FOR MANUFACTURING THE SAME

摘要

A steel sheet for soft-nitriding has a composition containing: C: 0.05% or more to 0.10% or less; Si: 0.5% or less; Mn: 0.7% or more to 1.5% or less; P: 0.05% or less; S: 0.01% or less; Al: 0.01% or more to 0.06% or less; Cr: 0.5% or more to 1.5% or less; Nb: 0.005% or more to 0.025% or less; and N: 0.005% or less, on a mass percent basis, such that C and Nb satisfy 0.10≦Nb/C≦0.30 (where C and Nb are respective contents of the elements (by mass %)), wherein balance comprises Fe and incidental impurities, and a microstructure that is a complex-phase microstructure containing ferrite and pearlite, and the microstructure having a ratio of a microstructure other than the ferrite and the pearlite of 1% or less, and the microstructure having a ratio of polygonal ferrite in the ferrite of less than 50%.

主权项

1. A steel sheet for soft-nitriding, having:
a chemical composition containing:
C: 0.05% or more to 0.10% or less;Si: 0.5% or less;Mn: 0.7% or more to 1.5% or less;P: 0.05% or less;S: 0.01% or less;Al: 0.01% or more to 0.06% or less;Cr: 0.5% or more to 1.5% or less;Nb: 0.005% or more to 0.025% or less; andN: 0.005% or less, on a mass percent basis, such that C and Nb satisfy the formula 0.10≦Nb/C≦0.30, where C and Nb are respective contents of the elements (by mass %),wherein balance comprises Fe and incidental impurities, and a microstructure that is a complex-phase microstructure containing ferrite and pearlite, the microstructure having a ratio of a microstructure other than the ferrite and the pearlite of 1% or less, the microstructure having a ratio of polygonal ferrite in the ferrite of less than 50%.