99热这里-欧亚av-色先锋av-国产草逼视频-91在线亚洲-成人性生活免费视频-午夜影院污-樱桃香蕉视频-精品久久久一区-男人天堂亚洲天堂-国产美女视频一区-欧美一级性片-av在线色-99r在线视频-一区二区的视频

      The factors that increase the cold brittleness of high-precision cold drawn tubes are:

       1. Solid solution strengthening elements. Phosphorus increases the toughness-to-brittleness transition temperature very strongly; there are also molybdenum, titanium and vanadium; elements that have little effect when the content is low but increase the toughness-to-brittleness transition temperature when the content is high include silicon, chromium and copper; elements that lower the toughness-to-brittleness transition temperature include nickel, and manganese that first lowers and then increases the toughness-to-brittleness transition temperature.

       2. Elements that form two phases. The element that is very important in increasing cold brittleness in the second phase is carbon. With theHigh precision cold drawn tubeAs the medium carbon content increases, the pearlite content increases. For every 1% increase in pearlite volume, the ductile-brittle transition temperature increases by an average of 2.2°C.

       3. The grain size affects the toughness-to-brittleness transition temperature. As the grains coarsen, the toughness-to-brittleness transition temperature increases. Refining the grains reduces the cold brittleness tendency of high-precision cold drawn tubes, which is a widely used method.