Evaluation of extremely steep residual stress gradients based on a combined approach using laboratory‐scale equipment

• Published in: Journal of applied crystallography 2021-12, Vol.54 (6), p.1793-1798
• Main Authors: Fischer, Andreas, Degener, Sebastian, Liehr, Alexander, Niendorf, Thomas
• Format: Article
• Language: English
• Subjects: angle‐dispersive diffraction; energy‐dispersive diffraction; Laser beam hardening; Laser beam heating; Laser cooling; laser surface hardening; Research Papers; Residual stress; residual stress analysis; Surface layers; Surface treatment; X-ray diffraction
• ISSN: 1600-5767; 0021-8898; 1600-5767
• DOI: 10.1107/S1600576721010335

Surface treatments characterized by rapid heating and cooling (e.g. laser hardening) can induce very steep residual stress gradients in the direct vicinity of the area being treated. These gradients cannot be characterized with sufficient accuracy by means of the classical sin2Ψ approach applying angle‐dispersive X‐ray diffraction. This can be mainly attributed to limitations of the material removal method. In order to resolve residual stress gradients in these regions without affecting the residual stress equilibrium, another angle‐dispersive approach, i.e. the universal plot method, can be used. A novel combination of the two approaches (sin2Ψ and universal plot) is introduced in the present work. Prevailing limits with respect to profiles as a function of depth can be overcome and, thus, high‐resolution surface layer characterization is enabled. The data obtained are discussed comprehensively in comparison with results elaborated by energy‐dispersive X‐ray diffraction measurements. This paper reports on high‐resolution analysis of residual stress gradients for a laser‐hardened surface layer using a combined angle‐dispersive X‐ray diffraction approach that applies the universal plot method and sin2Ψ evaluation.