日韩一卡2卡3卡4卡新区亚洲_日韩aaa一级片_久久婷婷五月综合色国产_91青青国产在线观看精品_免费在线视频一区_国产乱人视频免费观看网站

How to choose the material of roller

1.The selection of work roll material the work roll (R1) in the front section of roughing mill: the Work Roll in the front section of roughing mill must have strong toughness, wear resistance and hot cracking resistance. The hardness range is about HS40 -- 55. 60CrNiMo cast steel rolls are generallyused.