Mapping Residual Stress Distributions in Advanced High Strength Steel Automotive Body Panels and Structural Components

Automobile manufacturers have experienced increasing consumer and regulatory pressure to improve fuel efficiency and crashworthiness while simultaneously decreasing overall vehicle body weight. As such, the use of advanced high strength steels (AHSS) in body panels and other structural elements is becoming more and more prevalent because these advanced materials present an economical and elegant solution to the problem. To ensure the quality and safety of AHSS components, residual stress (RS) specifications (among others) have been introduced with the intent to minimize failures experienced both in the field and during production. Moreover, when welding processes are applied to AHSS components, the localized loss of ductility in combination with tensile RS can result in localized cracking, distortion, and/or failures. Spot checks at critical locations (often selected using either modeling methods and by experience) are currently being performed however, the highest RS present in the component may be overlooked in some cases. To achieve a more thorough understanding of the range and distribution of potentially harmful RS in AHSS components, large areas can be characterized using RS mapping techniques. This paper will present several examples of RS maps collected on various geometries on AHSS automotive body panels and structural elements demonstrating the variation and range of RS present.