退火工艺对含铒5A06铝合金组织性能影响

Effect of Annealing on Microstructures and Mechanical Properties of Er Bearing 5A06 Al Alloy

对含铒5A06铝合金进行75~450℃,1h退火处理和75、150、200、250、275、300、400、470℃的从0.5~100h退火处理,并对退火后的合金进行硬度测试、光学显微镜分析、扫描电镜分析,发现退火温度对合金组织性能影响显著,退火时间对合金影响较微小。进行不同温度1h退火时,在75℃退火,合金硬度少量下降;在125~250℃温度退火,随退火温度增加合金硬度下降趋势较缓,耐腐蚀性普遍较低;在250~275℃退火后,合金硬度大幅下降,降幅达28%,但耐腐蚀性能显著提高;275℃以上温度退火,合金硬度变化趋于稳定。进行不同时间退火时,合金在小于200℃和大于275℃时硬度随时间的变化不明显,合金在任一温度下退火0.5h即可完成主要的组织性能转变,退火100与0.5h的合金组织性能差异不大,但在200~275℃区间内,随退火时间延长合金硬度连续下降,250℃退火时合金硬度随时间的延长下降最为明显。在本实验不同退火工艺下合金硬度HV均不小于850MPa。

The evolution of mechanical properties and microstructure of Al-5.7Mg-0.7Mn-0.1Zr-0.2Er alloy after different annealing processes were studied by means of hardness test, OM and SEM. The annealing processes are annealing at 75-450 ℃ for 1 h and annealing at 75, 150, 200, 250, 275, 300, 400, 470 ℃ for 0.5 to 100 h. The result shows that annealing temperature has a greater effect on mechanical properties and microstructure of the alloy than annealing time dose. Annealing for 1 h, there is few evolution on the tested alloy at annealing temperature 75 ℃. The hardness of the alloy decreases slowly when the annealing temperature is increased from 125 to 250 ℃, but the corrosion resistance is low. A great change occurs when the alloy is annealed from 250 to 275 ℃, i. e. the hardness rapidly decreased by 28%, while the corrosion resistance increased remarkably. The hardness of the tested alloy becomes stale after annealing above 275 ℃. After annealing for different time, most evolution of mechanical properties and microstructure complete within 0.5 h at any annealing temperatures; annealing under 200 ℃ or above 275 ℃, there is few distinction after annealing for 0.5 and 100 h. therefore, the hardness decrease continuously with annealing time prolonging in the range of 200-275℃, and the greatest decrease of the alloy appears at 250 ℃. The hardness HV of the alloy with different annealing process is no less than 850 MPa.