划痕对冷轧汽车钢板DC04磷化膜质量的影响

Effects of Scratch on Quality of Phosphating Film for Cold Rolled Automobile Steel Sheet DC04

冷轧汽车钢表面形貌对磷化膜的形貌、致密性及相组成有很重要的影响,但在包装、运输等过程中难免会产生部分划痕。采用表面粗糙度仪、扫描电镜、X射线衍射仪等检测设备,分析人工划痕对冷轧汽车钢DC04表面粗糙度、磷化膜形貌及物相组成的影响。结果表明,DC04母板表面的粗糙度Ra平均值为1.124μm,峰值密度RPc平均值为76.5 cm^(-1),人工打磨后,粗糙度Ra基本不变,峰值密度RPc略有降低;和磷化前相化,DC04所有试样表面的粗糙度Ra变化不大,但峰值密度RPc略有升高;有人工划痕试样表面磷化膜局部结构不连续,磷化相中不致密四水合磷酸锌Zn_(3)(PO_(4))_(2)·4H_(2)O的含量为100%,致密的四水合磷酸亚铁锌Zn_(2)Fe(PO_(4))_(2)·4H_(2)O的含量为零,“P比”值为零,磷化效果较差。

The effects of surface morphology for cold rolled automobile steel on the morphology,compactness and phase composition of phosphating film are very important,but there would be inevitably some scratches in such processes as packaging and transportation.The effects of artificial scratches on the surface roughness,morphology of phosphating film and phase composition of cold rolled automobile steel DC04 are analyzed with such test equipment as the surface roughometer,scanning electron microscope and x-ray diffractometer.The results showed that the average value of surface roughness Ra was 1.124μm for mother blank of DC04,average value of peak density RPc was 76.5 cm^(-1),Ra basically unchanged and RPc decreased slightly after artificial grinding;Ra of all samples for DC04 changed a little,but RPc increased slightly compared with those before phosphating;local structure of phosphating film on the surface of sample with artificial scratch was discontinuous,content of incompact zinc phosphate tetrahydrate,Zn_(3)(PO_(4))_(2)·4 H_(2)O in the phosphating phase was 100%,content of compact zinc ferrous phosphate tetrahydrate,Zn_(2)Fe(PO_(4))_(2)·4 H_(2)O and value of“P ratio”were zero,so the phosphating effect was poor.