挤压速度和挤压温度对汽车用AZ31B镁合金工件表面质量的影响

Effect of Extrusion Speed and Extrusion Temperature on Surface Quality of AZ31B Magnesium Alloy

主要研究了挤压速度和挤压温度两个工艺参数对AZ31B镁合金工件成形过程中表面粗糙度和显微硬度的影响。结果表明：当挤压速度小于2.8 mm/s时,提高挤压速度能降低镁合金的表面粗糙度数值,改善表面质量;当速度超过3.0mm/s时,反而会提高粗糙度数值,对表面质量产生负面影响。提高挤压温度也能降低镁合金的表面粗糙度数值,当挤压温度到达360℃后,表面粗糙度不再发生变化,表面质量趋于稳定。当挤压速度小于2.4 mm/s时,提高挤压速度能提高镁合金的显微硬度,改善镁合金的表面质量;但速度超过2.4mm/s后,显微硬度迅速降低,造成表面质量急剧下降。当挤压温度小于360℃时,提高挤压温度也能提高镁合金的显微硬度,温度超过360℃后,显微硬度明显降低。

The effects of two process parameters （extrusion speed and extrusion temperature ）on the surface roughness and micro-hardness of AZ31B magnesium alloy workpieces during forming process were investigated. The result shows that： when the extrusion speed is less than 2.8 mm/s, increasing the extrusion speed can reduce the surface roughness value of magnesium alloy and improve the surface quality; when the speed is more than 3.0 mm/s, the roughness value will be increased and there is a negative impact on the surface quality. Increasing the extrusion temperature can also reduce the surface roughness value of magnesium alloy. After the extrusion temperature reaches 360℃, the surface roughness changes no longer, and the surface quality tends to be stable. When the extrusion speed is less than 2.4 mm/s, increasing the extrusion speed can improve the micro-hardness of magnesium alloy and improve the surface quality of magnesium alloy; however, after the speed is over 2.4mm/s, the micro-hardness decreases rapidly, resulting in a sharp decrease on surface quality. When the extrusion temperature is less than 360℃, the micro-hardness of the magnesium alloy can be improved by increasing the extrusion temperature, and the micro-hardness decreases obviously after the temperature is above 360℃.