成人免费a视频,李雅在线观看一区国产,五月婷婷狠狠,精品国产自在2o18,狼伊人,五月天丁香婷婷网,久久亚洲精品无码观看不卡

　　The material QML45Mn2 of Xingtai Iron and Steel Corp.,Ltd mainly used to produce the rivets for train. For this steel ,it has stable composition, low content of residual elements and strict size control. A terminal customers used the product for a long time, very few quality question, and has switched all procurement of raw materials to our products.