| 摘要 |
PURPOSE:To obtain a hot-rolled steel plate for general use which can be covered on the surface by performing a forming processing without surface treatment by hot-rolling a continuous billet of low carbon steel of a specified compsn. by directly heating or mildly heating and winding at a specified temp. thereafter, and cooling to a specified temp. in a nonoxidizing atmosphere. CONSTITUTION:Hot billet is obtd. by melting and then casting continuously a compsn. consisting of 0.03-0.25wt% C, <0.03wt% Si, 0.20-1.00wt% Mn, <=0.020 wt% P, <=0.020wt% S, <=0.05wt% Al, <=0.03wt% Cu, <=0.03wt% Cr, and residual wt% Fe. The product is roughly or finishedly rolled at hot as it is or after heating (mildly) its end part, etc. where temp. drop is liable to be cuased, to prepare plate of desired thickness, and wound at high temp. at 550-700 deg.C. The wound coil 1 is placed on a supporting stand 4 on the working floor 2 and is held in air-tight closed state by covering with a closing cover 8. Then, N2 or Ar is blown from nozzles 5a-5f, and the coil 1 is cooled in inert atmosphere until it attains 350 deg.C. |
