Microstructure and Growth Kinetics of High Strength Low-alloy Steel with Hot-dipping of 55%Al-Zn-1.6%Si (≤0.1%Ti)
PEI Jin-bang WU Guang-xin ZHANG Jie-yu WANG Bo
School of Materials Science and Engineering, Shanghai University College of Materials Science and Engineering, Shanghai University College of Materials Science and Engineering, Shanghai University Department of Nonferrous Metallurgy, Northeastern University
Abstract：Microstructure and growth kinetics of high strength low-alloy steel (H420) with hot-dipping 55%Al-Zn-1.6%Si (≤0.1%Ti) and 55%Al-Zn-1.6%Si were comparatively investigated. Optical microscope, SEM with energy dispersive spectrometer (EDS) and XRD were used to study the intermetallic layer thickness, microstructure, elemental distribution and phase composition. The results showed that the intermetallic layer was composed of Fe2Al5, Fe4Al13 and Fe-Al-Si intermetallic compound. A small amount of Fe-Al-Si-Mn solid solution existed in the border area between Fe2Al5 and Fe4Al13 phases, the reason was possibly that Mn diffused into the intermetallic layer. Meanwhile, the growth mechanism of intermetallic layer was characterized. The growth rate of intermetallic layer followed the parabolic law, Ti addition decreased the thickness of total intermetallic layer and Fe2Al5 layer about 3.25 and 1.83 mm. Ti-Al bond-energy was greater than Fe-Al one, Ti addition affected the interaction of Fe-Al bond, so the growth of intermetallic compound was restrained, and eventually reduced the intermetallic layer thickness.
2013, Vol. 13 
