| 摘要 |
PURPOSE:To prevent hot cracking by subjecting a stainless steel billet contg. specific ratios of Mo and N and having a columnar crystal to soaking in a specific high temp. region and blooming at a large rolling reduction then to hot rolling. CONSTITUTION:The billet consisting of the stainless steel contg., by weight, >=4% Mo and >=0.10% N and having the columnar crystal is soaked at 1,200-1,260 deg.C and is bloomed at the increased rolling reduction (about >=8mm) per pass at 1,250-1,150 deg.C. The resulted bloom is thereafter hot rolled and in this case, the rolling temp. at <=1,150 deg.C can be adopted. With the steel ingot or slab having a large thickness, the temp. falls before rolling down to the thickness for finish rolling and the required rolling reduction is not obtainable in the above-mentioned temp. range in some cases. In such a case, the better result is obtd. if the blooming is interrupted at the point of the temp. when the temp. falls down to about 1,150 deg.C, then the blooming is executed after reheating. The surface crack of the slab during the rough rolling in particular and the edge crack of the hot rolled coil are decreased and prevented by the above-mentioned method. |
