摘要
研究低强度电磁交互作用(EMILI)对改进间接电弧(MIEA)焊7075-T651铝合金板(厚度为13 mm)的显微组织和耐腐蚀性能的影响。焊接过程为单道次,热输入约为1.5k J/mm。通过测量显微硬度和电化学阻抗谱分别研究EMILI对局部力学性能和天然海水中耐蚀性的影响,并将其与焊缝的显微组织观察结果相关联。焊缝的显微组织表征表明,在电磁搅拌作用下,3mT的EMILI使焊缝金属的晶粒细化。此外,扫描电镜观察表明,热影响区(HAZ)的富铜相析出和共晶偏析也因受到EMILI的影响而减少。使用3 mT的EMILI焊接可以减少7075-T651焊缝在天然海水中的腐蚀溶解性和热影响区的过时效程度。因此,EMILI结合MIEA技术可使焊接接头具有更好的显微组织特征,能改善热影响区的力学性能,降低电化学活性。
The effects of applying an electromagnetic interaction of low intensity(EMILI) on the microstructure and corrosion resistance of 7075-T651 Al alloy plates(13 mm in thickness) during modified indirect electric arc(MIEA) welding were investigated. The welding process was conducted in a single pass with a heat input of ~1.5 kJ/mm. The microstructural observations of the welds were correlated with the effect of EMILI on the local mechanical properties and the corrosion resistance in natural seawater by means of microhardness measurements and electrochemical impedance spectroscopy, respectively. Microstructural characterization of the welds revealed a grain refinement in the weld metal due to the electromagnetic stirring induced by EMILI of 3 mT during welding. In addition, observations in the scanning electron microscope showed that the precipitation of Cu-rich phases and segregation of eutectics were reduced in the heat affected zone(HAZ) also as an effect of EMILI. The high corrosion dissolution of the 7075-T651 welds in natural seawater and the extent of overaging in the HAZ were reduced when welding with EMILI of 3 mT. Thus, EMILI along with the MIEA technique may lead to welded joints with better microstructural characteristics, improved mechanical properties in the HAZ and reduced electrochemical activity.
引文
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