Effect of alloy preheating on the mechanical properties of as-cast Co-Cr-Mo-C alloys

Abstract

The effect of various alloy preheatings followed by full solid solution treatments on the resultant strength and ductility of as-cast Co-Cr-Mo-C alloys was investigated. Three preheating temperatures were evaluated: 815 ЊC, 950 ЊC, and 1100 ЊC for 4 hours and then solid solution treated at 1225 ЊC for 4 hours. Tensile and compressive tests were carried out on the heat-treated alloys. It was found that the strength and ductility of the heat-treated alloys exhibited significant improvements over the as-cast condition. In particular, optimum ductility of the heat-treated alloys and alloy strength were promoted by preheating at 815 ЊC. A relatively fine grained structure coupled with a uniform distribution of second-phase particles promoted homogeneous plastic deformation in the bulk. Fractographic observations indicated that the exhibited ductility was associated with the development of numerous plastic bands combined with band interlockings. Alloy preheats at 950 ЊC and 1100 ЊC prior to solutionizing lead to inferior strength and ductility. Although preheating at 1100 ЊC led to slight improvements, in both cases, the fracture path was dominated by the presence of continuous carbide films surrounding the dendritic grains. Hence, less than optimum combinations of strength and ductility were achieved by the heat treatments at the higher temperatures.

Effect of Carbon Addition on Microstructure and Mechanical Properties of a Wrought Co–Cr–Mo Implant Alloy

“…It is thought that C additions significantly increase the stacking fault energy (SFE) of the alloys and thereby decrease the density of stacking faults, twins and " martensites. 8) Thus, as observed in Fig. 1(f), the increased SFE of 0.18C probably decreases the thickness of " martensites and the spacing between them.…”

Synthesis of Co-Cr-Mo Fluorapatite Nano-Composite Coatings by Pulsed Laser Deposition for Dental Applications

“…Unfortunately this material could not be applied to customized crowns and bridges because of their low strength [8] [9] [10]. Cobalt-chromium-molybdenum (Co-Cr-Mo) alloys have been widely used as removable partial dentures metal frames and porcelain-fused-to-metal crowns [11] [12] [13]. The reason for this is that these materials are strong and resistant to corrosion.…”

“…These alloys have also been used in other application such as in orthopedics, for bone fixation devices, total hip and knee replacements in both the cast and wrought forms. However, despite these properties, the fabrication processes, such as casting, cutting and plastic works are usually difficult due to their high melting point (1623 -1723 K), hardness and limited ductility [14] [15]. Therefore, this contribution reports on the fabrication of FA/Co-Cr-Mo nanocomposite using Pulsed Laser Deposition method and a possible application in dentistry.…”

Mechanical Characterization of CoCrMo Alloys Consisting of Different Palladium Ratios Produced by Investment Casting Method

“…Various carbide microstructures [2] can be produced which in turn might lead to improved alloy strength. In particular, the development of stacking faults and twins during alloy heat treating seems to play a key role in the resultant carbide distribution and morphology [3].…”