热镀锌钢板成形后镀层脱落原因分析

Cause analysis of zinc coating peeling off GI sheet after forming

对成形后镀层脱落的热镀锌钢板镀层组织进行了观察,从抑制层形成机制、热浸镀工艺等方面对镀层脱落的原因进行解析。结果表明,镀层发生脱落原因是由于基板表面抑制层不完整,发生铁锌合金反应生成脆性的铁锌合金相,在变形过程中,镀层从铁锌合金相处破坏并产生剥离脱落。建议通过优化以下关键工艺以提高产品质量:提高带钢表面清洁度、严格控制锌液中铝含量、合理控制热浸镀工艺等。经过以上工艺优化与严格控制,最终得到了抑制层连续致密的合格镀锌板产品。

The galvanized steel(GI) sheet which coating peel off when forming was observed and analyzed by scanning electron microscope(SEM) and energy dispersive spectrometer(EDS).The reasons and solutions were discussed through the formation mechanism of inhibiting layer,the process technology for galvanizing and other aspects.The results show that,the reason for the coating peel off was the incompleteness of the inhibiting layer.Zinc-iron alloy coating formed through ferrum and zinc reaction,which was fragile and peel off from the zinc-iron coating when forming.It is suggested that several critical processes should be optimized to improve the product quality including to improve the strip surface cleanliness,strictly control the aluminum content in melting zinc,rational control the galvanizing process.Qualified GI sheet products with continuous inhibition layer were obtained due to such optimized process and strictly control.