锌液中的Al含量对热冲压钢锌层组织的影响

Effect of Al Content on the Microstructure of Hot-Depped Zinc Coating on Hot Stamping Steel

采用热镀锌模拟实验装置在四种不同铝含量锌液中进行连续热镀锌实验,分别制备出具有不同锌层组织的热冲压钢。用扫描电镜、能谱仪和辉光放电光谱仪等手段研究了锌液中不同铝含量对热冲压钢镀层组织形貌的影响。结果表明,在不同铝含量的锌液中热冲压钢均具有良好的可镀性,锌液中的铝含量对锌层/钢界面处的合金层组织、形貌、化学成分和锌层光亮性均有较大的影响。在光亮退火过程中钢板表面发生锰、硅等元素的富集及选择性氧化,且Mn-Si氧化物与锌液中的铝发生氧化还原反应。锌液中的铝含量(质量分数,下同)为0.11%时,锌层/钢界面处形成了连续的ζ相;当锌液中的铝含量为0.17%时,锌层/钢界面处由Fe-Al相和ζ相组成;当铝含量为0.25%时,界面层主要为粗糙的Fe2Al5颗粒;铝含量为0.43%时颗粒状的Fe2Al5相消失,界面层变得光滑。同时,随着锌液中铝含量的提高锌层的光亮性逐渐变差。

Different galvanized coatings on hot stamping steel was obtained by using hot dip galva- nizing simulation experiment device dipping in zinc baths with four different AI contents. The effect of AI content on the microstructure of galvanized was investigated using SEM/EDS and glow discharge optical emission spectrometer （GDOES）.The results show that press-hardened steel has good reactive wetting in different AI content zinc bath. The AI content （mass fraction） in zinc bath has a significant influence on coating/steel interface composition, morphology and light property. Enrichment of Mn, Si elements oc- curred in the steel surface during bright annealing process, and the Mn-Si oxides react （redox reaction） with Al in zinc bath. For 0.11% dissolved Al bath, continuous ζ phases formed at the coating/steel inter- face. For 0.17% dissolved Al bath, the coating/steel interface consist of ζ, phases and Fe-AI phases. A continuous Fe2Al5 inhibition layer achieved in baths with AI content 0.25% and 0.43%, and the morpholo- gy of interface layer became coarser when AI content in zinc bath was 0.25%. In addition, with the in- crease of AI content in zinc bath, the light property of zinc coatings gradually became worse.