Effect of Microstructure and Mechanical Properties of Welded Joint of A7N01P-T4 Alloy by Grinding Size

铝合金具有密度低、强度高、挤压性能好、焊接性优良及加工性能好等特点，已经成为高速列车车体生产的主导材料。在铝合金车体生产过程中，焊接技术是使用最为广泛的生产加工方式。高速列车铝合金车体焊接完成后，焊缝部位会形成一定的余高。余高不但影响高速列车整体结构尺寸精度，还会影响高速列车的安全可靠性，因此为了满足实际使用要求，大部分焊接接头均要求打磨余高。因而焊缝余高打磨工艺的研究是相当必要的。本文研究了不同打磨粒度对A7N01P-T4铝合金对接接头疲劳性能的影响。结果表明不同打磨粒度铝合金对接接头抗拉强度，延伸率差别不大。不同打磨粒度对铝合金对接接头疲劳性能的影响多变的。疲劳裂纹源均萌生于焊缝缺陷，多见于气孔，夹渣与硬质相，因而焊接接头的质量对疲劳性能的影响占主要原因。 Aluminum has a low density, high strength, good extrusion performance, good weldability and ex- cellent processing performance and other characteristics, which has become the dominant vehicle production materials of high-speed trains. In the aluminum car body production process, welding technology is the most widely used production and processing method. After the completion of high-speed train’s aluminum body welding, Weld will be a certain reinforcement. Weld reinforcement will not only affect the overall structure of the dimensional accuracy, but also affect the safety and reliability of high-speed trains, so in order to meet the actual requirements, most of the welded joints require more than a high polish. Thus, research on weld reinforcement grinding process is very necessary. This article studied on the effect of different polished size on the fatigue properties of A7N01P-T4 aluminum butt joints. The results showed that different size polished aluminum butt joints tensile strength has little difference on elongation. Effects of different grinding size on the polished aluminum butt joints fatigue properties change greatly. Fatigue crack initiation in weld defects was more common in the pores, slag and hard phase. Thus the main reason that affecting the fatigue performance of welded joints is the welding quality.