汽车用合金化热镀锌板镀层剥离行为的分析

Peeling Behavior of Hot-Dipped Galvanizing Alloying Coating on Automobile Steel Sheets

为了研究合金化热镀锌层与基体的剥离性能,设计了一种用于剥离合金化热镀锌层的特殊试验装置和专用胶。利用该装置可以在普通的万能拉伸仪上将合金化热镀锌层从镀锌板基体上剥离下来,同时测定出其镀层脱落过程的剥离力,发现镀层剥离时剥离力曲线趋于水平线。扫描电镜观察结果显示,镀层整体与基体分离,X射线衍射分析剥离前试样由Г,Г1,δ和α-Fe相构成,剥离后基体侧含有Г,Г1,α-Fe相,镀层侧只有Г,Г1和δ相。这说明合金化热镀锌层在外力的作用下出现了沿镀层与基体的交界层(Г+Г1)开裂而发生剥离。

A special apparatus was developed to peel hot-dipped galvanizing coating from automobile steel sheet substrate.Using the apparatus,the galvanized coatings were peeled off zinc-plated steel sheets with a universal drawing test rig,and the peeling load of the galvanized coatings was meas-ured.Moreover,the morphology of the cross-section of the galva-nized coating was observed using a scanning electron microscope,and the changes in the phase composition of the samples before and after peeling test was analyzed by means of X-ray diffraction.Results indicated that the curve of peeling force during the peel-ing process tends to horizontally.The original coating sample was mainly composed of Г,Г1,δ,and α-Fe phases.The fractured sub-surface near to the substrate consisted of Г,Г1,and a-Fe phases,but only Г,Г1,and δ phases were detected at the frac-tured zones in the galvanized coatings.Thus it was inferred that the coating experienced fracture along the interface of the coating and substrate and was further peeled off.