Research On Enhancing Technolog Of Laser Rapid Forming Nickel-Based Superalloy By Ultrasonic Impact Treatment

Laser cladding forming (LCF) based on rapid prototyping and laser cladding is an advancedmanufacturing technology for direct cladding forming metal parts. LCF is benefit for savingmanufacturing costs and shortening product development cycles, which is widely used in aerospace,medical and other fields. However, parts made of LCF have some flaws, such as: inhomogeneitymicrostructure, larger residual stress, poor forming quality, poor performance. These defects directlyaffect the normal using of parts. Laser cladding layer is the foundation of formed parts. Then deeplyresearching on laser cladding layer to controll microstructure, forming quality, residual stress is theonly way for solving the problems of formed parts.Ultrasonic impact treatment (UIT) can strengthen the performance of part by applying highimpact on surface of the part, making plastic deformation, resulting in beneficial effects on thematerial microstructure and stress state. UIT has advantages of portable devices, significantlyenhanced effects, better process suitability, which is widely used in relieving residual stress,manufacturing nanocrystalline layer of metal surface, strengthening repairing parts and other fields.The most significant changes of parts after UIT are grain refinement and residual stress elimination,so defects are reduced and performance of parts is increased. Against the problems of laser claddinglayer, if UIT is combined with laser cladding forming to explore solutions to the problems issignificance. Currently, researches on relieving residual stress and grain refinement of laser claddinglayer by UIT have not been reported.Based on UIT, laser cladding forming nickel-base superalloy as the research object, the maincontent of this article is process research on strengthening laser cladding layer by UIT and analyzingthe strengthening mechanism and law. The specific research contents are as follows:(1) Based on the dis location theory, analyzing the mechanism of grain refinement and res idualstress elimination for laser cladding layer by UIT, and providing guidance for the subsequenttheoretical and experimental researches.(2) The numerical simulation analysis of laser cladding layer stress field with and without UIT iscarried out. The formation mechanism and laws of laser cladding stress field and the effects areanalyzed by using the finite element simulation technology.(3) Process researching on single-pass nickel-base superalloy laser cladding layer with UIT. Themain analysis is the influence of morphology and grain size of laser cladding layer after UIT. Bes ides, the micro-hardness of laser cladding layer is measured and analyzed to provide guidance forsubsequent research.(4) Process researching on multi-pass nickel-based superalloy laser cladding layer with UIT. Themain analysis is macro-morphology, surface roughness, microstructure, microhardness and residualstress of laser cladding layer after UIT for determining the specific effect of laser cladding forminganickel-based superalloy microstructure and residual stress. Strengthening mechanism of multi-passlaser cladding layer by UIT is obtained.