过时效段露点对双相钢表面色差的影响

Influence of over-aging dew point on surface color difference of dual phase steel

冷轧双相钢具有较高的抗拉强度和较低的屈强比,成形性能优异,被汽车工业广泛用于生产形状比较复杂的结构件。由于冷轧双相钢中含有较多的易氧化的合金元素如锰、硅等,因此在退火时容易出现表面色差缺陷。采用镀锌模拟器研究了退火的过时效段工艺对该缺陷的影响,分别采用扫描电镜和辉光放电光谱分析了冷轧双相钢试样的表面形貌以及元素分布。结果表明,过时效段的露点温度对表面合金元素的富集和氧化有显著影响,较高的过时效露点温度会导致出现明显的色差缺陷。

With high strength and low yield-tensile ratio, dual phase steel has been applied to manufacture structural parts with complex geometry in automobile industry as good forming property. Due to large amount of alloying elements tended to be oxidized, such as manganese and silicon, contained in the dual phase steel, color difference defect is apt to appear during annealing. In this study, influence of over-aging processes on the defect was studied with a hot-dip pro- cess simulator. The surface micrograph and element depth profile of the dual phase steel samples were investigated by means of scanning electron microscopy （SEM） and glow discharge optical emission spectroscopy （GDOES）, respec- tively. The results indicate that the dew point during over-aging remarkably affects the microstructure and enrichment of alloying elements on the surface. Higher dew point during over-aging results in severe color difference defect.