CHARACTERIZATION OF THE SOLID-STATE BONDING FOR SIMULATED CHARGE AND SEAM WELDS IN THE PORTHOLE DIE EXTRUSION PROCESS

The isothermal (ISO-T) compression configuration is ideal for utilizing as a material input of flow stress at temperature and strain rate in models of the porthole die extrusion process due to the isothermal nature of the test. Micro-tensile testing was conducted to validate the solid-state welding integrity of the ISO-T samples at various temperatures and strain rates. Results of the mechanical testing were correlated with fractography and microstructural evaluations of the welds to confirm bonding behavior. Both clean interface conditions and oxidation and lubrication layers were evaluated to simulate the difference of seam and charge welds in the process. Results show increasing strain rate and temperature positively affect bonding conditions. The presence of barrier layers of both oxidation and lubrication negatively affect the weld integrity.