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

　　Xingtai steel’s XG10B21 products are mainly used in the production of 8.8 bolt. Customers reflects the product composition is stable, high dimensional accuracy. For the free of annealing processing, it can directly reduce the production cost. Because of containing B elements, it has good hardenability. Drawing performance stability, cold heading does not crack, performance stability after heat treatment. The end products made by this material widely used in mechanical fasteners.