Al-Mg-Zn铝合金的高温力学性能研究

摘要

7系Al-Mg-Zn合金是广泛应用于高速列车车体结构的材料,本研究所用材料为轧制后经过固溶处理并自然时效处理的热处理强化板材.在列车车体的焊接制造过程中,由于焊接热源作用导致接头区域出现不均匀温度分布,并在冷却后产生残余应力.采用Gleeble-3500热模拟试验机进行高温拉伸试验,研究高温下7系铝合金的力学性能变化.试验结果表明,随着温度的升高,铝合金的强度逐渐降低,同时延塑性随之改善,但在300℃时,延伸率出现了极小值.此外,随着温度的升高,拉伸断口由脆性倾向转变为韧性断裂,且韧窝变大、变深.拉伸断口的形貌和拉伸结果表现出较好的一致性.%7XXX Al-Mg-Zn alloy was widely used in high-speed train manufacture.In this paper,the aluminum alloy was heat treated by solution treatment along with natural aging process.During the welding process,uneven temperature distribution would be caused by heat sources,and residual stress distribution would be generated after cooling.High temperature tensile test by Gleeble3500 testing machine was introduced to study the mechanical properties of the aluminum alloy.The results indicated that the aluminum alloy strength decreased gradually with increasing of temperature,while ductility was improved and the elongation reached to a trough at 300 ℃.In addition,the tensile fracture was translated to ductile fracture with increasing of temperature.The fracture morphologies showed a good consistent with tensile results.