High strength steel hot-dip galvanizing technology high strength steel has always been the focus of research.
Identity of often contain more Si, Mn and other elements, these elements in the substrate surface enrichment, makes the hot galvanizing occurs when a variety of surface defects, Japan through the adjustment of chemical composition, especially Mo element, add, has realized the commercial production of hot dip galvanized dual phase steel alloying, low Si containing, dual phase steel has been on the traditional hot galvanizing production line, for commercial production, for example: DP600:0.07% 0.10% C, 1.0% 1.8% Mn, Si, 0.4% 0.6% to 1.2%.(Cr+ Mo), <0.01%S, <0.06%P, 0.02%0.06%Al, <0.03% (Ti+Nb), its yield strength and tensile strength reached 320MPa and 630MPa respectively, with a total elongation rate of 26% and an n value of 0.18. High-strength steel with high Si content is still the main research direction at present. Therefore, it is necessary to study the control of atmosphere and dew point in the furnace of the annealing furnace, and pretreatment of the substrate can also solve the surface enrichment problem of Si and other elements.
On the basis of alloying hot dip galvanized dual phase steel, kawasaki, Japan iron and steel company has developed the 590-980 mpa grade with good sex of spot welding of low carbon equivalent type alloying galvanized steel , recent IFE Japan iron and steel company was successfully developed a higher level of degree of alloying hot dip galvanized dual phase steel 21.TRIP steel (i.e., phase-change induced plastic steel) has excellent formability, strength and impact resistance, and is used to reduce weight and save energyIdeal steel. However, TRIP steel with high Si content is not suitable for production on existing hot-dip galvanizing production line, which is also because the enrichment of Si tends to lead to the leakage of plating defects. Although by controlling annealing furnace in the dew point can change the strip surface chemical composition, so as to improve the quality of coating, but not completely eliminate the plating leakage area, in addition, the isothermal transformation temperature due to the limitation of zinc pot temperature is too high, so can't get enough of residual austenite in 129], the study found that replace Si with Al of TRIP steel· it can be comparable to the performance of traditional CMnSi TRIP steel, and.It is suitable for the existing hot dip process, has the very good plating can be , but as A result of A1 elements added, to the steelmaking and hot rolling process brings many problems, how to solve these problems is one of the focus in the study of TRIP steel galvanizing, X.V anden Eynde et al., 130 type containing Si TRIP steel is put forward to pre heating forming A first oxidation layer, and then the reduction of new technology, in the experiment, the room in the study found that the process of hot dip galvanized steel have good don't TRIP.