Residual Stress Measurement in Steel Beams Using the Incremental Slitting Technique

This paper examines the application of the incremental slitting technique for residual stress measurement to plastically deformed four-point bent beams and autogenously edge welded steel beams. Initially a study into a number of factors affecting the series expansion approach was conducted. Due to the over-determined nature of the series expansion approach appropriate selection of polynomial series order was necessary to develop the best prediction. The effect of elasto-plastic properties in experimental situations creates local slit tip yielding which could led to errors particularly at shallow depths and in near slit gauges. The specimens used for the plastic four-point bending were manufactured from ferritic steel with dimensions of width 10mm, depth 25mm and length 250mm. These experiments were conducted to create a better understanding of the incremental slitting procedure and its experimental application. The measured stresses were found to be in reasonable agreement with the FE predictions. A set of autogenously welded ferritic beams of width 10mm, depth 50mm and length 180mm were also measured. These beams were edge welded to create a through depth residual stress field. Residual stress measurements for two different weld torch speeds were obtained. We show that a suitably chosen set of polynomials and gauge locations produce residual stress measurements with an uncertainty of about 7MPa.