Processresearch Ofnickel Alloys Partsin Laser Cladding Forming

Laser cladding forming technology has a lot of remarkable advantages, such as high forming efficiency, suitable for a wide range of materials and high manufacture flexibility and so on. As a result, it can manufacture parts that are difficult to process by using conventional processing methods. However, forming quality is difficult to control due to the mutual coupling of process parameters, rapid melting and solidifying of the metal powder and high temperature, convection, mass transfer phenomena during forming process. Therefore, it is very important for improving the forming quality to study the effects of process parameters on forming precision, forming microstructure and its performance.This paper discussed the current research situation and development trends of precision control of the forming shape, forming quality control and porous parts forming. Morphology prediction model of single-channel cladding, overlapping rate prediction and modified model, Z-axis increments pre-estimate mode are established. Discuss the effect of process parameters on macroscopic morphologies, microstructure morphology and mechanical properties. Specific research contents are as follows:First of all, establish a mathematical model to predict the morphology of single-channel cladding layer based on the relationship between energy input of the laser weld pool and width of cladding layer. It characterize the functional relationship between process parameters and cladding layer morphology and can directly reflect the influence of process parameters on the morphology of the cladding layer, which has great practical value. For higher precision demanding applications, establish a numerical simulation of geometric morphology model based on ANSYS transient temperature field.Then analyze the influence of process parameters on cladding layer height uniformity of multi-channel overlapping. At the same time, establish overlapping rate prediction and modified model for optimizing matching relationship between process parameters and overlapping rate and improve the surface properties of the cladding layer. Conduct multilayer stacking experiments based on single-channel cladding and multi-channel overlapping cladding to establish Z-axis increments pre-estimate mode for guaranteeing the macro dimensional accuracy of forming parts. In addition, conduct porous forming experiments to study the effect of offset distance on porosity and its connectivity rate, and the findings provide experimental evidence for preparation of porous parts.Finally, observe metallurgical structure of cladding layer, measure microhardness of cladding layer at different locations and conduct compression performance test for porous nickel alloy. Experimental results show that the ratio of temperature gradient(G) and weld pool solidification rate(R) determines the metallurgical structure and microhardness of cladding layer. If the value of G/R is large, metallurgical structure of cladding layer is finer, at the same time, microhardness of cladding layer is greater. If the value of G/R is small, the experimental results are opposite to the former. It also establish the relationship between porosity and compressive modulus, so we can obtain the desired compression modulus by adjusting the porosity.