一种无余量叶片定向凝固工艺的研究

Directional Solidification Process of a Net-shape Blade

通过一种无余量叶片的定向凝固工艺试验,确定了该叶片的浇注系统、定向凝固工艺参数。结果表明,定向叶片在浇注系统中的分布方式及引晶位置对柱状晶的生长和温度场分布有直接影响,带冠叶片将引晶段与榫头相接能够更好地防止叶片扭曲变形,减少叶片表面缩松、裂纹等缺陷。由正交试验发现,型壳预热温度、浇注温度过低及拉晶速率过快不利于柱状晶的生长和保证凝固面的温度梯度。型壳预热温度为1 510~1 520℃,浇注温度为1 510~1 520℃,拉晶速率为5.0mm/min时,能够更好地消除叶片表面斜晶、断晶,获得品质稳定的定向凝固细直柱状晶叶片。

By directional solidification experiment for a net-shape blade,gating system and directional solidification parameters,sucha s shell preheating temperature,pouring temperature and withdrawal velocity,were optimized.The results show that,in the design of gating system,the blade distribution mode and seeding position are directily relavant with the grain growth and the distribution of temperature field.It is suitable for connecting the seeding with the tenon to avoid distorting deformation of the blade and reduce the metallurgical defects（such as loose,cracks）in the blade.The orthogonal testing reveal that it exhibits negative effects on the grain growth and the solidified surface temperature gradient with a lower shell preheating and pouring temperature or a higher withdrawal velocity.The optimized directional solidification parameters were presented as follows：shell preheating at 1 510~1 520℃,pouring at 1 510~1 520℃and the withdrawal velocity of 5.0mm/min,where the blade with stable thin straight columnar crystal and absence of the surface oblique or broken grain.