| 摘要 |
Provided is an abrasion resistant steel plate or steel sheet, suitable for use in construction machines, industrial machines, and the like, excellent in resistance to stress corrosion cracking and a method for manufacturing the same. A steel plate or steel sheet has a composition containing 0.20% to 0.27% C, 0.05% to 1.0% Si, 0.30% to 0.90% Mn, P, S, 0.005% to 0.025% Nb, 0.008% to 0.020% Ti, 0.1% or less Al, and 0.0010% to 0.0060% N on a mass % basis, the composition further containing one or more of Cr, Mo, W, and B, the composition containing one or more of Cu, Ni, V, an REM, Ca, and Mg as required, the remainder being Fe and inevitable impurities. The steel plate or steel sheet has a DI* of 45 or more and a microstructure having a base phase or main phase that is tempered martensite. Nb/Ti-containing precipitates having a grain size of 0.01 µm to 0.5 µm in terms of equivalent circle diameter is present in the steel plate or steel sheet at 2 × 10 2 grains/mm 2 or more. After being heated, a semi-finished product having the steel composition is hot-rolled and is subjected to reheat-quenching or direct quenching. |
