预镀镍层对一种C-Mn-Si高强钢选择性氧化行为的影响

Influence of Prior Nickel Plating on Selective Oxidation Behavior of a C-Mn-Si High Strength Steel

目的抑制高强钢中合金元素在表面选择性氧化。方法在一种C-Mn-Si体系高强钢表面预先电镀100 nm厚度的镍,然后在镀锌模拟器上进行模拟退火处理。使用扫描电镜及其附属的X射线能谱仪观察分析了试样表面形貌和元素构成,使用辉光放电光谱仪研究了样品退火后表面的元素深度分布,使用X射线光电子能谱鉴定了样品退火后的表面化合物种类。结果预镀镍样品退火后,表面存在一层疏松的镍层,少量颗粒状氧化物分布在镍层表面;而未镀镍样品退火后,则在表面晶界和晶粒中均出现颗粒分布的氧化物。延长退火时间会显著增加表面氧化物的数量,降低表面镍含量。辉光放电光谱分析表明,表面沉积的镍镀层能够抑制合金元素在表面的选择性氧化。退火10 s后,Mn元素的表面富集量减少了52%,Si元素的表面富集量减少了23%;而退火50 s后,Mn元素和Si元素的表面富集量均减少42%。X射线光电子能谱分析表明,镀镍样品表面的氧化物以不定型氧化物为主,而未镀镍样品表面的氧化物主要为晶态氧化物。结论100 nm厚度的预镀镍能够有效降低Si和Mn向外的扩散速率,抑制Si和Mn元素在表面的富集程度,改变表面选择性氧化产物的种类,减少高强钢表面氧化物的数量。

The study aims to suppress selective oxidation on the surface of an advanced high strength.A C-Mn-Si highstrength steel was electrodeposited with prior nickel plating with the thickness of 100 nm,and then annealed in a galvanizing simulator.The surface morphology and elemental composition of the samples were studied using scanning electron microscopy(SEM)and energy dispersive X-ray spectroscopy(EDS)attached,respectively.The element depth distribution in the surface layer of the samples was studied through a glow discharge spectrometer(GDS).X-ray photoelectron spectroscopy(XPS)was used to identify the category of the compounds on the external surface.The annealed sample with prior-nickel plating could be found to have a loose nickel layer on the surface and some oxides could be observed on the nickel layer.For the annealed sample without prior-nickel plating,oxides could be found in the boundaries and in the grains.With annealing time prolonging,more oxides appeared on the surface and less nickel content was detected.GDS results revealed that the nickel plating deposited on the surface could inhibit the selective oxidation of alloy elements on the external surface.As annealed for 10 s,enrichment of Mn on the surface was reduced by 52%and enrichment of Si on the surface was reduced by 23%.As annealed for 50 s,enrichment of Mn and Si on the surface were both reduced by 42%.X-ray photoelectron spectroscopy analysis showed that the oxides on the surface of the nickel-plated samples were mainly amorphous oxides,while a large amount of crystalline oxides appeared on the surface of the nickel-free samples.It was indicated that that prior nickel plating with 100 nm thickness can effectively decrease diffusion rate of Si and Mn,suppress the enrichment of Si and Mn on the external surface,change the type of surface selective oxidation products,and reduce the amount of surface oxides on high-strength steel.