Repair method of backup roll surface of steckel mill and special repair powder used thereon

The invention relates to a machinery part surface repairing method in the metallurgical industry, in particular to a repairing method of steekle mill supporting roller surface and specially used repairing powder; the repairing powder contains the components with the following weight percent: 0.2 percent to 0.5 percent of C, 14 percent to 20 percent of Cr, 6 percent to 12 percent of Ni, 0 percent to 1.5 percent of Mn, 1 percent to 2.5 percent of Mo, 0.5 percent to 2.5 percent of W, 1.5 percent to 2.5 percent of Si, 2.0 percent to 3.0 percent of B, and the rest is Fe. When a supporting roller cannot be used any more because the roller surface is worn or locally falls off, areas to be repaired are molten through a laser process with the repairing powder, so that the missing and damaged parts are repaired and the performance of the repaired parts can meet the use requirements; and then, the shape of the roller surface is recovered through mechanical processing, and a reusable supporting roller can be obtained without heat treatment.