Abstract: The present invention provides an abrasion resistant steel having a hardness of HB400 to HB520, having little change of hardness during long term use, and superior in toughness, characterized by containing, by mass %, C: 0.21% to 0.30%, Si: 0.30 to 1.00%, Mn: 0.32 to 0.70%, P: 0.02% or less, S: 0.01% or less, Cr: 0.1 to 2.0%, Mo: 0.1 to 1.0%, B: 0.0003 to 0.0030%, Al: 0.01 to 0.1%, and N: 0.01% or less, further containing one or more of V: 0.01 to 0.1%, Nb: 0.005 to 0.05%, Ti: 0.005 to 0.03%, Ca: 0.0005 to 0.05%, Mg: 0.0005 to 0.05%, and REM: 0.001 to 0.

Abstract: A corrosion-resistant steel excellent in toughness of a base metal and a weld portion said steel slab contains, in % by weight, C: 0.2% or less; Si: 0.01 to 2.0%; Mn: 0.1 to 4% or less; P: 0.03% or less; S: 0.01% or less; Cr: 3 to 11%; Al: 0.1 to 2%; and N: 0.02%, and has values of 1150 or above, and 600 or above respectively for Tp and Tc expressed by the equations below using concentrations of Cr, Al, C, Mn, Cu and Ni respectively given as % Cr, % Al, % C, % Mn, % Cu and % Ni. Tp=1601?(34% Cr+287% Al)+(500% C+33% Mn+60% Cu+107% Ni); and Tc=910+80% Al?(300% C+80% Mn+15% Cr+55% Ni).

Abstract: The present invention provides steel plate excellent in machineability and in toughness and weldability and a method of production of the same. Steel with C, Si, Mn, P, S, Al, and N limited to predetermined ranges and further containing, as necessary, Mo, Cr, Nb, Ti, V, Cu, Ni, B, REM, Ca, Zr, or Mg is further strictly defined in the balance of steel ingredients and strictly controlled in the conditions of rolling, water cooling, etc.