一种新型镍基粉末高温合金挤压工艺研究

Extrusion test study on a novel nickel-based Powder metallurgy Superalloy

摘要:

针对一种新型粉末高温合金WZ-A3进行了一系列的热挤压工艺试验,探究了挤压温度、挤压速度、挤压比对棒材显微组织的影响以及棒材的整体组织均匀性。结果表明：在恒定挤压速度35 mm/s、挤压比4.7:1条件下,挤压温度为1110 ℃时,合金棒材已发生完全动态再结晶,当挤压温度继续增加,晶粒发生明显长大。在恒定挤压温度1110 ℃、挤压速度35 mm/s条件下,挤压比为2.1:1时,合金再结晶不完全而且存在较多原始颗粒边界；当挤压比增加至4:1~4.7:1时,再结晶程度完全充分,PPB也完全消除。在恒定挤压温度1130 ℃、挤压比4.7:1条件下,在20~50 mm/s范围内随着挤压速度的增加,晶粒呈长大趋势。在挤压温度1110 ℃、挤压速度35 mm/s、挤压比4.7:1条件下整个挤压棒材的组织较为均匀,从棒材头部到尾部,晶粒略微细化,并且棒材边缘的组织较心部和1/2R更细小。

Abstract:

A series of hot extrusion tests were carried out for a novel powder metallurgy superalloy WZ-A3. The effects of extrusion temperature, extrusion speed, and extrusion ratio on the microstructure and the microstructure uniformity of the extruded bar were investigated. The results show that under the conditions of a constant extrusion speed of 35 mm/s, an extrusion ratio of 4.7:1, and an extrusion temperature of 1110 ℃, completely dynamic recrystallization of the extruded bar occurs. With the increase of the extrusion temperature, the grain coarsens. Under the conditions of a constant extrusion temperature of 1110 ℃, an extrusion speed of 35 mm/s, and an extrusion ratio of 2.1:1, the recrystallization is incomplete and there are more PPB left. When the extrusion ratio increased to 4:1~4.7:1, complete recrystallization is achieved, PPB can also be completely eliminated. At an extrusion temperature of 1130 ℃ and an extrusion ratio of 4.7:1, in the range of 20-50 mm/s extrusion speed, the grains tend to grow much larger. At an extrusion temperature of 1110 ℃, an extrusion speed of 35 mm/s, and an extrusion ratio of 4.7:1, the microstructure of the entire extruded bar is rather uniform. From the head of the bar to the tail, the grains are slightly refined. The grains at the edge of the extruded bar are smaller than that at the core and 1/2R.