| 摘要 |
PURPOSE:To obtain a stainless clad steel plate of >=5mm. product thickness having high corrosion resistance in the stage of cooling the clad steel plate after the end of hot rolling by specifying temp. region and cooling rate. CONSTITUTION:After stainless steel is laminated on a carbon steel or low alloy base material, the materials are hot-rolled to produce a stainless clad steel plate of >=5mm. product thickness. Here, the clad steel plate after the end of the hot rolling is quickly cooled at 1,200-7,200 deg.C/hr cooling rate in the temp. region of the lower temp. of either the rolling end temp. and the Ar3 transformation point of the base material steel plate -600 deg.C. Here if the thickness is <5mm., there is no formation of Cr23C6 near the clad interface which degrades corrosion resistance even if the steel plate is allowed to air-cool. The quick cooling temp. region is made the temp. lower than the Ar3 transformation point or the rolling finish temp. which is seldom lower extremely than said point because the diffusion of C to the stainless steel layer is mainly from the ferrite of the base material. Since the deposition of the Cr23C6 is highest at 720-600 deg.C, the temp. range is limited at 600 deg.C. The cooling rate is required to be higher than the lower limit in order to suppress the diffusion of C but in excess of the upper limit, bainite is deposited. |
