摘要
建立了空心叶片激光快速成形过程温度场瞬态有限元数值模型,模拟了TC4钛合金空心叶片激光快速成形过程的温度场演变过程。结果表明:空心叶片激光快速成形温度场随熔池的移动及凝固和空心叶片逐层连续叠加沉积而动态演化。开始阶段,熔池较小,冷却速率较大(–1735℃/s左右),温度梯度较高(8.34×105℃/m左右),随着熔覆高度的增加,熔化区扩大,熔池冷却速率减小,温度梯度降低,3/4叶片高度处熔池重熔深度大于上两层熔覆层高度,熔池冷却速率为–438℃/s,熔池温度梯度为3.67×105℃/m,成形结束时,激光快速成形空心叶片温度沿Z轴方向呈梯度分布,基座内温度沿Z轴方向上升较慢,温度梯度为5×103℃/m,而从叶片根部到其顶部温度上升较快,温度梯度为2.6×104℃/m,到达叶片顶部温度为1542℃左右,表明虽然随熔覆高度的增加成形叶片表面换热作用加强,但整体散热方向没变,仍是从上至下,从熔池到基座。
The finite-element model of transient temperature field for hollow blade during laser rapid forming （LRF） process was developed. The transient temperature field evolution during laser rapid forming （LRF） process for TC4 alloy hollow blade was simulated by adopting the birth and death technology and the enthalpy potential method. The results show that the cooling rate and temperature gradient of melting pool are high about -1735 ℃/s and 8.34 × 105 ℃/m, respectively, in the early stage for first layer melting pool. With increasing the deposited height of blade, the cooling rate and temperature gradient of melting pool become lower gradually. When the melting pool is about three quarter-height of the blade, the cooling rate is about -438 ℃/s and the temperature gradient is about 3.67 × 10^5 ℃/m. At last, when the process of laser rapid forming is finished, the temperature distribution in hollow blade is from low （30 ℃ at bottom of substrate ） to high （1542 ℃ at top of blade） along the vertical （Z axis） direction, the temperature gradient in substrate is smaller （about 5 × 10^3 ℃/m） than that of in the blade （about 2.6× 10^4 ℃/m）, and the main thermal transpiration direction is from top to bottom, and from melting pool to substrate.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2007年第7期1193-1199,共7页
Rare Metal Materials and Engineering
基金
国家自然科学基金项目(50331010
50201010和50405038)资助
