熔焊对碳钢渗铝层组织和抗氧化性能的影响

Influence of Fusion Welding on Microstructure and Oxidation Resistance of Aluminized Layer on Carbon Steel

采用钨极氩弧焊焊接了热浸镀铝后真空扩散的Q235钢板,采用光学显微镜、SEM、EDS、XRD等研究了熔焊对渗铝层组织及高温(800℃)抗氧化性能的影响。结果表明:渗铝层与焊缝之间实现冶金结合,铬、镍、铝元素在熔合线附近呈现梯度分布,熔合线附近的主要物相为Al_2Cr、AlCrFe_2以及(Fe,Cr)固溶体;焊后试样的氧化-增重曲线近似抛物线,熔合区氧化膜的主要物相为Al_2O_3、Cr_2O_3和Fe_2O_3,焊后渗铝试样的高温抗氧化性能比焊接前仅下降了22.8%。

Vacuum diffusion Q235 steel after hop dip aluminizing was welded by tungsten gas arc welding. The effect of fusion welding on microstructure and high-temperature （800 ℃ ） oxidation resistance of the aluminized layer was investigated by means of optical microscopy, scanning electron microscopy, energy dispersive spectra and X-ray diffraction. The results show that the interface between aluminized layer and welding seam was metallurgical bonding. The elements of Cr, Ni and Al near fusion line gradiently distributed. The main phases near fusion line were Al2Cr, AlCrFe2 and （Fe, Cr） solid solution. The oxidation-mass gain curves of the post-weld sample were nearly parabolic. The main phases of the oxidation film in fusion zone were Al2O3, Cr2 Oa and Fe2O3. Comparing with the high-temperature oxidation resistance of the aluminized sample before welding , the one of the sample after welding only decreased by 22. 8%.