不卡视频一区二区三区,婷婷成人av,国产精品一区视频,久久夜色精品国产噜噜av小说,国产精品性夜天天视频,亚洲日产永久经典,九九国产精品入口麻豆

　　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.