Process-oriented modeling and simulation of unsteady modulated gas flows in plasma powder cladding to influence layer properties

本研究项目的目的是开发一种方法来识别和表征时变非平稳调制工艺气流对等离子熔覆过程中的熔体反应的影响，关于振荡和电流。可以预期的是，可以通过硬质颗粒的有利分布和通过细化显微组织来实现机械性能的改善。两种合金将作为硬质材料粉末引入到等离子弧中。这两种合金是钨铬钴合金和钨铬钴合金以及碳化钨。钴钨铬钴合金粉末将通过焊接熔池固化过程改变，使得枝晶生长被中断，以便获得更细晶粒的存款。具有添加的碳化钨的钨铬钴合金的目标是通过搅拌焊池以抵消碳化钨的重力偏析来实现碳化钨在整个焊缝中的均匀分布。这项调查的结果应该有可能有一个基本的了解瞬态工艺气流在PTA硬面工艺方面所产生的物理效应，并开发经济用途，从这方面的知识。这些知识可用于通过改变这些覆盖层的微观结构和宏观结构来提高该工艺的磨损性能，并且还可用于扩展当前的应用边界。

The objective of this research project is to develop an approach to identify and characterize the effects of time-varying non-stationary modulated process gas streams on the melt reaction during plasma cladding with regards to oscillation and current. It is expected that an improvement in the mechanical properties can be achieved with a favorable distribution of hard particles and through refinement of the microstructure. Two alloys will be introduced as hard material powder to the plasma arc during this investigation. The two alloys are a stellite cobalt alloy and a stellite alloy alongside tungsten carbides. The cobalt stellite powder will be altered by the weld pool solidification process such that dendritic growth is interrupted, in order to obtain a more fine-grained deposit. The goal for the stellite with the added tungsten carbides is to achieve an even distribution of tungsten carbides throughout the weld by agitating the weld pool to counteract gravity segregation of the tungsten carbides. The results of this investigation should make it possible to have a basic understanding of transient process gas streams in a PTA hardfacing process with regards to the resulting physical effects and to develop economic uses from this knowledge. This knowledge can then be used to enhance the wear properties of this process by changing the microstructure and macrostructures of these overlays, and furthermore be used to expand upon the current application boundaries.