鍛造-圧延プロセスによる連続鋳造スラブ製高品質極厚鋼板の製造

抄録

Heavy section steel plates have been usually manufactured in ingot casting process for the requirement of good internal properties. We have newly applied the combined forging and plate rolling process using continuous casting slabs in place of ingot casting process for the economical point of view. The applying of this manufacturing process was possible both homogeneous and sound internal properties of steel plates. The forging method with reduction in widthwise and thickness wise direction of slabs was greatly effective for annihilation of center porosities. By the application of this process, the excellent internal properties can be obtained in the manufacture of heavy section steel plates with thickness of up to 240mm which means the reduction ratio of thickness from a strand cast slab to plate: 1.29. The properties at the center of plate thickness could be greatly improved by increase of slab reheating time before forging due to easy diffusion of center segregation elements in continuous casting slabs.
This combined forging and plate rolling process was approved as special practices mitigating the reduction ratio limitation on ASME 2002 Addenda SA-20⁄SA-20M (Standard specification for general requirements for steel plates for pressure vessels).