| 摘要 |
PURPOSE:To obtain the steel plate efficient in welding characteristics for high heat input at low cost, by a method wherein the coagulation and coarsening of titanium carbonitride of the titanium containing steel of a fixed composition are controled and further, the uniform distribution of fine titanium carbonitride is achieved. CONSTITUTION:The high temperature slab of the steel consisting of 0.05- 0.15wt% C, 0.2-0.5% Si, 0.5-2.0% Mn, 0.005-0.15wt% Ti, 0.005-0.1% Al, 0.005-0.0030% B, 0.001-0.03% REM and 0.008% max. N, containing not less than one components of 2.0% max. Ni, 1.0% max. Cu, 0.05-0.3% Cr, and 0.01- 0.05% V when required and remainder Fe, is cooled by an average cooling rate 0.3 deg.C/sec min. from melting and solidification to a rolling sart temperature of 1,100 deg.C max., and directly hot-rolled without reheating and keeping before rolling. Because in the steel products thus obtained, titanium carbonitride are finely precipitated, with the larger the heat input, the slower cooling, and the effect of fine titanium precipitation is remarkably generated. |
