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研究了激光快速成形(LRF)Rene 80高温合金厚壁件的凝固组织和裂纹的形成机理。结果表明,激光快速成形Rene 80高温合金的凝固组织为与沉积高度方向平行的定向凝固枝晶组织,由于凝固偏析,MC型碳化物和γ-γ′共晶组织分布于定向凝固组织的枝晶间区域。激光快速成形Rene 80高温合金厚壁件含有许多长度大于10mm,扩展方向与沉积高度方向平行的宏观裂纹。分析表明,这些裂纹为液化裂纹,其形成原因为:激光快速成形时,紧邻激光熔池的热影响区(HAZ)内沿晶界分布的低熔点γ-γ′共晶组织发生熔化,形成热影响区内沿晶界扩展的晶界液相,在热影响区冷却过程中,由于热影响区内固相的收缩应力作用,沿晶界扩展的固-液界面被撕开,从而导致液化裂纹的产生。
The formation mechanism of solidification microstructure and crack in laser rapid prototyping (LRF) Rene 80 superalloy thick-walled parts was studied. The results show that the solidified microstructure of Rene 80 superalloy is a directionally solidified dendritic structure parallel to the deposition height. Due to the segregation of solidification, the MC type carbides and γ-γ ’eutectic structure are distributed in the dendrites Room area. Laser rapid prototyping Rene 80 superalloy thick-walled elements contain many macrocracks that are longer than 10 mm in length and parallel in direction to deposition height. The analysis shows that these cracks are liquefied cracks. The reason for these cracks is that when the laser is rapidly formed, the low-melting γ-γ ’eutectic structure distributed along the grain boundary in the heat-affected zone (HAZ) of the laser weld pool melts to form a hot Affect the region along the grain boundary grain boundary liquid phase in the heat-affected zone cooling process, due to the heat-affected zone solid phase shrinkage stress, along the grain boundary of the solid-liquid interface is torn open, resulting in liquefied cracks The production.