Analysis of the Microstructure and Hardness of a Direct Digital Manufactured Metal Used for an Acetabular Cup Implant

Abstract

Total hip arthroplasty, or the total reconstruction of the hip, is commonly used to relieve patients of pain due to the failure of the hip joint to perform its natural function, due to trauma or disease. One of the main components in total hip arthroplasty is the acetabular cup. New advancements in additive manufacturing allow direct digital manufacturing of metal parts, such as an acetabular implant. Direct digital manufacturing allows for lower cost in production, faster production time, and higher customization, but if the mechanical properties do not match up to the traditionally made metal implants, they cannot be used. This research was conducted to investigate how the mechanical properties of a direct digital manufactured biocompatible metal compare to the casted metal. This was done by analyzing the microstructure with an optical microscope of a direct digital manufactured titanium alloy, Ti6Al4V, sample made using an Arcam electron beam melting machine. The hardness of this sample was also measured using the Vickers hardness test. The direct digital manufactured Ti6Al4V sample showed a finer grain structure and a higher hardness than cast Ti6Al4V. This suggests that the mechanical properties will be higher in the direct digital manufactured acetabular implant than in a cast implant. However, currently the casted metal is cold worked and then heat treated, so further research needs to be conducted to determine the microstructure and mechanical properties of heat treated, direct digital manufactured Ti6Al4V.