Numerical Simulation and Defect Identification in the Casting of Co-Cr Alloy

Abstract

The development of biomaterials, particularly metallic ones, is one of the focuses of the scientific community, mainly due to an increase of average life expectancy and an improvement of the casted materials combined with better mechanical properties and defect-free products. The use of cobalt alloys in applications, such as knee, hip, and dental prostheses, is the result of their good ability to maintain mechanical properties and biocompatibility over long periods of use. Numerical methods are becoming more important, as they help product improvement in a faster and economic way. This work focuses on the development of a numerical model in ProCAST®, comparing the shrinkage porosity and cooling curves with real castings. When correlating simulation results with available experimental data, it is possible to understand that the formulated model demonstrates an acceptable solution in terms of precision (shrinkage porosity and cooling curve). The alloy’s thermal properties and heat conditions were iteratively changed until the developed numerical model turned out a viable tool for this specific alloy when used in the investment casting process.

Scratch and Wear Behaviour of Co-Cr-Mo Alloy in Ringer’s Lactate Solution

“…The pouring of the Co-Cr-Mo alloy occurred at t = 373 s. In previous work, we simulated and produced the Co-Cr-Mo alloy. The time of pouring established in the simulation was 373 s, which was adopted for alloy production in the furnace [ 6 ].…”

“…Twenty minutes after pouring, the casting and ceramic shell were removed from the vacuum furnace and cooled to room temperature. The ceramic shell was then cracked via a knockout process, and the cast sample was cleaned [ 6 ]. Increasing the EMS frequency resulted in a reduction in the grain size.…”

“…Alloys based on cobalt and chromium have been employed in highly demanding medical applications [ 5 ], such as knee and hip implants, due to their excellent ability to maintain their mechanical properties and biocompatibility over long periods of use [ 6 ]. Hip joint replacement is one of the most successful orthopaedic surgeries [ 7 ].…”

“…These microstructural changes affect the alloy’s mechanical and wear properties, while the microstructure and composition of the alloy affect its corrosion behaviour in body fluids, due to changes in surface chemistry [ 16 , 17 , 18 , 19 ]. In previous work [ 6 ], it was shown that modification of the investment casting process, using electromagnetic stirring (EMS) during solidification, resulted in a decrease in the size of the Co-Cr-Mo alloy grains, representing innovation in the manufacture of these alloys. However, it remains necessary to investigate whether there are associated improvements in the alloys’ mechanical properties (wear resistance and hardness).…”

Effect of Dynamic Preheating on the Thermal Behavior and Mechanical Properties of Laser-Welded Joints

“…The finite element model (FEM) was established using Ansys software. The overall framework of the numerical simulation is shown in Figure 3 [ 21 , 22 , 23 ]. The inverse bremsstrahlung of the laser and arc at 1030 nm can be ignored [ 3 , 24 ].…”