激光熔化沉积CoCr合金微观组织及力学性能研究

Study on the Microstructure and Mechanical Properties of CoCr Alloy Using Laser Melting Deposition

为了分析采用激光熔化沉积方式制备的CoCrMoW合金显微组织演变特征和力学性能,研究了不同激光功率下CoCrMoW合金多道单层涂层的显微组织演化、物相组成和力度性能。选取较优的工艺参数制备了多道多层块体试样,进一步研究多层试样的显微组织,并加工拉伸试样,研究CoCrMoW合金的力学性能。结果表明,随着激光功率的升高,CoCrMoW合金涂层的物相组成由不同取向的γ-Co和ε-Co组成,晶粒尺寸随激光功率增大逐渐粗化,导致显微硬度从346.14 HV_(0.2)(400 W)降低至309.62 HV_(0.2)(1000 W)。CoCrMoW合金多层试样的显微组织主要由等轴晶和柱状晶结构组成,块体顶部硬度略高于底部。沉积态CoCrMoW合金的平均抗拉强度为993.4 MPa、平均屈服强度为492.987 MPa,呈脆性断裂,断口形貌由光滑断面和解理面构成,有明显河流花样,断裂机制为解理断裂。

To study the microstructure characteristics and mechanical properties of the CoCrMoW alloy fabricated using laser melting deposition,we studied the microstructure evolution,phase composition,and mechanical property of CoCrMoW multi-track coatings at different laser powers.Multi-track and multi-layer samples were prepared by selecting better process parameters.Furthermore,we investigated the microstructure of multi-layer samples and processed the tensile samples to study the mechanical properties of CoCrMoW alloy.The results show that the phase composition of the CoCrMoW alloy coating consists of particles with different orientations,γ-Co and ε-Co compositions,and grain size coarsened gradually with the increase in laser power,decreasing the microhardness from 346.14 HV_(0.2)(400 W)to309.62 HV_(0.2)(1000 W).The microstructure of the CoCrMoW alloy multi-layer sample is mainly composed of equiaxed crystal and columnar crystal structures,and the microhardness at the top of the block is slightly higher than that at the bottom.Both the average tensile and yield strengths of the deposited CoCrMoW alloy are 993.4 MPa and 492.987 MPa,respectively,showing brittle fracture.The fracture morphology is composed of a smooth section and cleavage surface,with an obvious river pattern and cleavage fracture mechanism.