0Cr18Ni9Ti压力容器焊接工艺特点(国外英文资料).doc

0Cr18Ni9Ti压力容器焊接工艺特点(国外英文资料) Characteristics of welding process of 0Cr18Ni9Ti pressure vessel, a pressure vessel with stainless steel and its welding characteristics Refers to the so-called stainless steel chromium added a certain amount in the steel, the steel is passivated, has the characteristics of no rust. For this purpose, the chromium content must be above 12%. In order to improve the passivation of steel, stainless steel is often added to nickel and molybdenum steel passivation elements. The general point is actually a group of stainless steel and stainless acid resistant steel. Stainless steel is not necessarily acid, and acid resistant steel generally has a stainless steel with good performance. According to the different stainless steel steel structure can be divided into four categories, namely austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, AUSTENITIC FERRITIC duplex stainless steel. 1. austenitic stainless steel and its welding characteristics Austenitic stainless steel is the most widely used stainless steel, with high Cr-Ni type is most common. The austenitic stainless steel can be divided into Cr18-Ni8 type, Cr25-Ni20 type, Cr25-Ni35 type. Have the following characteristics of welding of austenitic stainless steel: The welding hot cracking of austenitic stainless steel due to its low heat conductivity, linear expansion coefficient, therefore in the process of welding, high temperature welded joint weld stay longer, easy to form columnar structure, in the solidification process, if the high impurity content of sulfur and phosphorus, tin, antimony, niobium etc. that will form a low melting point eutectic in intergranular, under high tensile stress of welded joints, is easy to form the solidification cracks in the weld, the formation of liquation crack in the heat affected zone, which belongs to the welding hot crack. The most effective way to prevent hot crack is prone to reduce impurities and low melting point eutec