Numerical Approximation of Solidification Behavior in Co-27Cr-5Mo-0.25C Alloys during Pulsed Laser and Tungsten Inert Gas (TIG) Welding of As Cast Biomedical Inserts
Mentor 1
Hugo Lopez
Location
Union 340
Start Date
27-4-2018 12:20 PM
Description
Emily A. Gerstein, gerstein@uwm.edu, Material Science and Engineering, CEAS, UWM
Hugo Lopez, Ph.D., hlopez@uwm.edu, Material Science and Engineering, CEAS, UWM
With an ever-aging global populace, an escalated need for biomedical implants with enhanced in vivo performance has posed itself as a challenge for the metallurgical community. Co-Cr-Mo alloys have been used for decades as orthopedic and dental implant materials because of their high hardness, strength, wear properties and corrosion resistance within the human body. While as cast implants have demonstrated favorable performance, failure to safely increase alloy ductility has led to premature device failure and in some cases leaching of toxic byproducts into surrounding tissues. To combat this issue, development of rapid solidification methods capable of producing fine cast dendrite or cellular structures upon cooling of liquid metal have garnered considerable interest as they may both reduce carbide size and allow for fine dispersal of alloying elements, in turn further enhancing mechanical properties. Surface modification and repair of implant materials using pulse laser and tungsten inert gas (TIG) welding where large amounts of undercooling in weld pools occurs have been shown to produce such structures and demonstrate potential for both increasing hardness and producing more favorable wear properties in Co alloys exposed to aqueous environments. To further understand the relationship between solidification and cast structure during welding, this work aims to develop a numerical scheme for capturing the effects of melting parameters on both the weld metal and heat affected zones (HAZ) developed in weldments using these methods. Through the generation of thermal profiles using classical Rosenthal assumptions, information regarding secondary dendrite arm spacing (DAS) may be determined, and considered alongside resulting carbide structure, alloy distribution, microhardness and wear behavior to construct a holistic view of how welding may enhance implant performance.
Numerical Approximation of Solidification Behavior in Co-27Cr-5Mo-0.25C Alloys during Pulsed Laser and Tungsten Inert Gas (TIG) Welding of As Cast Biomedical Inserts
Union 340
Emily A. Gerstein, gerstein@uwm.edu, Material Science and Engineering, CEAS, UWM
Hugo Lopez, Ph.D., hlopez@uwm.edu, Material Science and Engineering, CEAS, UWM
With an ever-aging global populace, an escalated need for biomedical implants with enhanced in vivo performance has posed itself as a challenge for the metallurgical community. Co-Cr-Mo alloys have been used for decades as orthopedic and dental implant materials because of their high hardness, strength, wear properties and corrosion resistance within the human body. While as cast implants have demonstrated favorable performance, failure to safely increase alloy ductility has led to premature device failure and in some cases leaching of toxic byproducts into surrounding tissues. To combat this issue, development of rapid solidification methods capable of producing fine cast dendrite or cellular structures upon cooling of liquid metal have garnered considerable interest as they may both reduce carbide size and allow for fine dispersal of alloying elements, in turn further enhancing mechanical properties. Surface modification and repair of implant materials using pulse laser and tungsten inert gas (TIG) welding where large amounts of undercooling in weld pools occurs have been shown to produce such structures and demonstrate potential for both increasing hardness and producing more favorable wear properties in Co alloys exposed to aqueous environments. To further understand the relationship between solidification and cast structure during welding, this work aims to develop a numerical scheme for capturing the effects of melting parameters on both the weld metal and heat affected zones (HAZ) developed in weldments using these methods. Through the generation of thermal profiles using classical Rosenthal assumptions, information regarding secondary dendrite arm spacing (DAS) may be determined, and considered alongside resulting carbide structure, alloy distribution, microhardness and wear behavior to construct a holistic view of how welding may enhance implant performance.
