Posted 16 Dec 2010 02:52
Hot dip galvanized dual phase steel, is through the returns processing, galvanizing and alloy microstructure obtained after processing of ferrite and martensite in the main, the surface layer of galvanized steel. Production, when cooling from the two-phase area, get some ferrite, the required rapid cooling, so that the cooling of austenite into martensite. Access to ferrite plus martensite dual-phase steel. Hot dip galvanizing process required under 460 ?galvanized infiltration, to continue to 500 ? the alloying hot dip galvanized. Therefore, the production of hot galvanized dual phase steel, the cooling rate is relatively low undercooling is small, get a good dual-phase steels is difficult. Currently, to solve this problem, commonly used methods are two kinds: one is the use of alloying elements, 2 is the use of zinc quenching. Quenching method as the cooling rate of zinc is too large, the quality of thin plate shape seriously affected, while difficult to control coating quality, the application is relatively small. The current widely used approach is to add some alloying elements, the system through a rational process to obtain the mechanical properties and coating quality are excellent products. The main alloying elements added to the main elements of Mo, while adding excess C, Si, Mn and other elements have a negative impact. Austenite into martensite before the C mass fraction of the maximum of not more than 0.3% is appropriate, the proposed C mass fraction of substrate should be less than 0.1%. The results show that, Mo elements that can improve the strength of dual phase steel, galvanized and can get good quality. Mo makes less prone to surface oxidation, there is no surface segregation does not affect the infiltration of liquid zinc; followed by Mo alloy galvanized steel sheet is not delayed reaction can be carried out at lower temperatures can reduce the alloy plating phase and the amount of powder coating; In addition, the added Mo CCT curve was shifted to the right will expand the area of ferrite, pearlite transformation occurs to prevent the cooling, which is conducive to the martensite phase when hot dip galvanized Steel .