国产色诱视频在线播放丝袜,国产丝袜无码一区二区三区,无码人妻丰满熟妇区五十路免费中文午夜精品久久久久久,精品高潮呻吟99AV无码视频,精品无码一区二区三区蜜臀很多小伙伴都喜欢看短视频,久久精品国产亚洲AV未满十八,99在线精品国自产拍中文字幕,国产精品一区不卡在线观看

Xingtai steel successfully developed and produced cold heading steel containing Nb for high end for the first time
  Updatetime:2018-11-19 Hits:

   Recently, Xingtai steel successfully developed and produced cold heading steel containing Nb for high end for the first time. The successful production of this steel fills the blank of cold heading steel containing Nb and diversifies the structure of high-end cold heading steel in Xingtai Steel.

  36MnB4 is a trademark of European standard. It belongs to typical middle carbon cold heading steel containing boron, which is mainly used to produce the rivets for new-energy vehicles. 36MnB4 also can replace the imported materials.This rivet not only requires high tensile strength, but also good toughness and formability after heat treatment. The toughness can be improved by adding Nb-base alloy refined grain to rivets. However, it is difficult to produce Nb containing steel slab which has strong crack sensitivity because it’s easy to occur cross cracks in its corner. The Technician of our company optimized the design of Nb content, selected ferroniobium, controlled nitrogen in LF refining, optimized second cooling technology and whole-course protected casting so that chemical component and surface quality of slab could meet customers’ requirements, which marks cold heading steel containing Nb for high end 36MnB4 was developed successfully at once.

国产午夜福利100集发布| 无码人妻精品一区二区蜜桃老年人| 久久AV无码精品人妻出轨| 天天综合网欲色天天影视 | 国偷自产一区二区三区在线观看| 99久久99久久精品免费看蜜桃| 最近中文字幕大全免费版在线| 在线观看少妇免费三级| 人妻av制服av中文字幕| 色欲久久久中文字幕综合| 丁香激情五月影院| 国产精品亚洲综合一区| 亚洲网站免费观看| 免费的黄色网站中文日韩欧美| 国产老妇伦国产熟女老妇视频| 国产最新a级毛片无码专区| 国产午夜亚洲精品理论片不卡| 天天天欲色欲色WWW免费| 亚洲精品无码?v人在线观| 国产精品永久久久久久久WWW| 国产一区二区三区精品视频| 99国产强伦姧在线看Rape| 国产麻豆乱子伦午夜视频观看| 人妻丰满熟妇无码区免费| 亚洲av无码国产日韩久久| 精品乱码一区内射人妻无码| 伊人色综合久久天天五月婷| 久久久久精品国产三级| 午夜福利无码国产精品中文| 闺蜜和我被黑人4P到惨| 亚洲AV秘无码一区二区在线| 亚洲制服丝袜另类中文字幕| 久久乐国产精品亚洲综合| 精品国在线观看视频在线播放| 成人免费视频深夜视频在线看网站| 国产精品综合专区中文字幕免费播放| 午夜性刺激在线观看| 亚洲无码一区二区在线观看| 欧洲亜洲中文日韩色图| 亚洲欧美一区二区成人片| 97欧美精品激情在线观看最新|