Residual Stress Measurements of Cold-Forged Ball Studs by the Contour Method

Toparli M. B., Kilincdemir N. E., Yurtdas S., Tanrikulu B., Ince U.

EXPERIMENTAL TECHNIQUES, vol.46, no.6, pp.919-930, 2022 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 46 Issue: 6
  • Publication Date: 2022
  • Doi Number: 10.1007/s40799-021-00521-w
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Applied Science & Technology Source, Communication Abstracts, Compendex, Computer & Applied Sciences, INSPEC, Metadex, Civil Engineering Abstracts
  • Page Numbers: pp.919-930
  • Keywords: Cold forging, Residual stress, Contour method, Ball stud, Cutting-induced artefacts, EIGENSTRAIN-BASED MODEL, PEENED ALUMINUM-ALLOY, PREDICTION, COMPONENTS
  • Dokuz Eylül University Affiliated: No


In this study, residual stresses of cold-forged ball studs were investigated by the contour method with using widely available wire-Electro-Discharging Machine (wire-EDM) and Coordinate Measuring Machine (CMM). After the wire-EDM cutting, one of the steps of the contour method, it was revealed that the surface contour data was affected from the cutting step. Therefore, to increase the accuracy of the measured residual stresses, one of the ball studs were heat-treated to normalize residual stresses due to cold forging. The contour data of the heat-treated sample was subtracted from the as-forged surface contour to eliminate any cutting-induced artefacts. The final residual stress profiles suggested that the subtracting procedure minimized the cutting errors. In addition, a new classification approach for the cutting-induced errors for the contour method was introduced. According to final stress maps obtained by the contour method, it was revealed that high compressive residual stresses were obtained at the socket regions of the ball studs, as expected. Balancing tensile residual stresses were observed at the inner regions.