21. The Flow Stress of AM IN 625 under Conditions of High Strain and Strain Rate

Additively manufactured (AM) nickel superalloy (In 625) with known processing history and quasi-static properties has been investigated under extreme strains up to about 100% and strain rate up to about 10⁴/s by machining. A model for the calculation of the component of force that is due to indentation by the tool cutting edge was utilized to correct the measured shear force and material flow stress. The results are compared to flow stress measurements produced by Kolsky compression testing under strains of about 25% and strain rate of about 10³/s. The highly instrumented setups utilized for the machining testing made possible an accurate description of the strain and strain rate at the primary shear zone (PSZ), and the temperature at the tool rake face that prevailed throughout the machining. The strain and strain rate were determined by digital image correlation. The temperature was determined by through-the-tool thermography. Differences observable during the cutting and dynamic compression of additive and wrought In 625 are outlined.