镍基合金激光快速成形裂纹控制技术

The Cracking Control Technology of Laser Rapid Forming Nickel-Based Alloys

裂纹控制技术是镍基合金激光快速成形技术广泛应用和进一步工业化的关键.从熔覆层金相组织、物相组成、残余应力、宏观形貌和断口观察等角度分析了Ni60合金激光快速成形裂纹形成的原因,提出了相应的裂纹控制策略.研究表明:Ni60合金的激光快速成形裂纹主要是由于硬脆相引起的熔覆层低延性及残余内应力导致的脆性冷裂纹.通过调整合金成分,优化工艺参数,以及引入超声振动等措施,可以改善镍基合金激光快速成形组织,提高塑韧性,降低残余内应力,从而降低裂纹敏感性,减少或消除裂纹.

Cracking control technology is one of the bottlenecks retarding the wide application and further industrialization of laser rapid forming nickel based alloys. This paper analyzed the reasons of the cracking generation in laser rapid forming nickel based alloys from the microstructure, phase composition, residual stress, macro morphology and fracture observation of the cladding layers. Corresponding cracking control strategies were also proposed. The investigations indicate that the cracks of laser cladding forming nickel based alloys are mainly the brittle cold cracks caused by low ductility induced by hard brittle phases and in- ternal residual stress resulted from high temperature gradients. Through the adjustment of alloy composition, optimization of process parameters, and introduction of ultrasonic vibration, laser rapid forming microstructures can be improved, plasticity and toughness can be enhanced, and residual stress can be reduced, therefore, the cracking susceptibility can be reduced and cracks can even be eliminated.