Speaker: Adam Cruezinger, NIST Center for Automotive Lightweighting
Title: Errors in Phase Fraction Measurements Caused by Crystallographic Texture
Abstract: The NIST Center for Automotive Lightweighting (NCAL) has several efforts to assist the automotive industry in relevant measurement problems, as many automotive manufacturers have identified vehicle lightweighting as the primary means to meet current and upcoming fuel economy targets. One such problem is measurement of phase fractions. A promising type of material under development is referred to as 3rd Generation Advanced High Strength Steels (3GAHSS). These steel alloys have high strength and high elongation, obtained by an initial mixture of phases and selective transformation during deformation. Therefore, accurate measurements of the phase fraction in the as-processed steel and as a function of deformation are key. Unfortunately, despite having used steel for nearly 4,000 years, this measurement remains a challenge. One of the largest factors affecting phase fraction measurements is crystallographic texture, or preferred orientation. Texture is inherent in the processing and deformation, and strongly affects diffraction (x-ray and neutron) phase fraction measurements. While it is widely recognized that crystallographic texture affects phase fraction measurements, the effect has largely been unquantified. This presentation will discuss methods to assess errors in phase fraction measurements caused by texture and techniques to minimize them.