Quantification of Residual Stress Relief by Heat Treatments in Austenitic Cladded Layers

The effect of the heat treatment on the residual stresses of welded cladded steel samples is analyzed in this study. The residual stresses across the plate’s square sections were determined using complementary methods; applying diffraction with neutron radiation and mechanically using the contour method. The analysis of the large coarse grain austenitic cladded layers, at the feasibility limits of diffraction methods, was only made possible by applying both methods. The samples are composed of steel plates, coated on one of the faces with stainless steel filler metals, this coating process, usually known as cladding, was carried out by submerged arc welding. After cladding, the samples were submitted to two different heat treatments with dissimilar parameters: one at a temperature of 620 °C maintained for 1 h and, the second at 540 °C, for ten hours. There was some difference in residual stresses measured by the two techniques along the surface of the coating in the as-welded state, although they are similar at the welding interface and in the heat-affected zone. The results also show that there is a residual stress relaxation for both heat-treated samples. The heat treatment carried out at a higher temperature showed sometimes more than 50% reduction in the initial residual stress values and has the advantage of being less time consuming, giving it an industrial advantage and making it more viable economically

Wear and surface residual stress evolution on twin-disc tests of rail/wheel steels

Twin disc tribological tests were performed in wheel and rail materials, with specimens taken from a Spanish AVE train wheel and a UIC60 rail, in a program intended to characterize their contact fatigue behavior. The X-ray diffraction technique was used to characterize the residual stress distribution at the initial and damaged stages, as well as in intermediate stages, since existing residual stresses in the surface layers of the railways steels and its evolution during contact loading can have a major influence on crack initiation and propagation

Deterioração por Fadiga de Contacto de Engrenagens Tratadas Superficialmente.

Engrenagens de uma caixa de velocidades de automóvel, com tratamentos superficiais combinados de carbonitruração e de grenalhagem de pré-tensão, foram submetidas a ensaios de fadiga de contacto. A duração dos ensaios foi suficiente para originar o aparecimento de picagem ("pitting") ou escamação ("spalling") na superfície dos dentes das engrenagens. A técnica da difracção de raios X foi utilizada para seguir a evolução de diferentes parâmetros mecânicos e metalúrgicos, em função do estado de deterioração das engrenagens, tendo-se dedicado uma atenção particular à relaxação das tensões residuais. Foi desenvolvido um modelo numérico para previsão da relaxação das tensões residuais e da localização mais provável de iniciação de fendas em fadiga de contacto. As leis de comportamento mecânico das camadas tratadas superficialmente foram identificadas por intermédio de uma metodologia original, utilizando ensaios de flexão 4-pontos associados com a técnica da difracção de raios X, e por ensaios de indentação esférica conjugados com uma análise numérica elastoplástica do processo de indentação. O critério multiaxial de fadiga de Dang Van foi utilizado para estimar a profundidade mais provável de iniciação das fendas de fadiga de contacto, tomando em consideração a influência do estado estabilizado de tensões residuais, do atrito e da rugosidade

Fatigue Performance of Thin Laser Butt Welds in HSLA Steel

This work is focused on understanding the significant factors affecting the fatigue strength of laser-welded butt joints in thin high-strength low-alloy (HSLA) steel. The effects of the weld profile, imperfections, hardness, and residual stresses were considered to explain the results found in the S-N curves of four welded series. The results showed acceptable fatigue strength although the welded series presented multiple-imperfections. The analysis of fatigue behavior at low stress levels through the stress-concentrating effect explained the influence of each factor on the S-N curves of the welded series. The fatigue limits of the welded series predicted through the stress-concentrating effect and by the relationship proposed by Murakami showed good agreement with the experimental results. © 2021 by the authors

Residual stresses profiles of cladded austenitic stainless steel evaluated by X-ray diffraction and by incremental hole-drilling method

Artigo em acesso restrito.The samples studied in this paper were carried out using carbon steel plates, cladded on one of the faces with stainless steel filler metals by submerged arc welding (SAW). After cladding, the samples were submitted to post-weld heat treatments under different conditions and then stainless steel coating surfaces were milled and mechanically polished, as in the industrial application. The residual stress analysis was performed by X-ray diffraction (XRD) and incremental hole-drilling methods (IHD). The residual stress profiles showed different values in-depth in each sample, depending on the heat treatment. The hole-drilling method was applied in several points of each stainless steel sample surface and the results presented similar profiles of evolution. However, compressive stresses increase when the heat treatment temperature rises

Evaluation of residual stresses induced by ultra-high-speed drilling in aluminium alloys

Rolling contact fatigue twin-disc tests were performed on rail/wheel steels from Spanish high velocity trains (AVE). Residual stress profiles were determined using X-ray diffraction before and after cyclic loading. The evolution of residual stress profiles, due to cyclic loading, was analysed in order to study how they affect the rolling contact fatigue behaviour of these materials. This study is included in a major project where other related phenomena and materials’ properties have been studied

Assessing shot-peening residual stresses by using the incremental hole-drilling technique and laser interferometry (DSPI)

Artigo em acesso restrito.The incremental hole-drilling technique was applied to determine residual stress profiles in shot-peened steel layers. The accuracy of using an enhanced Digital Speckle Pattern Interferometry technique for measuring the strain relaxation arising around the drilled holes and, consequently, the in-depth residual stress distribution induced by shot-peening, was evaluated. The experimental results were systematically compared with those determined using standard electric strain-gauges. The X-ray diffraction technique was chosen as reference due to its high accuracy to determine shot-peening residual stresses

X-ray diffraction residual stress measurements for assessment of rolling contact fatigue behaviour of railway steels

Artigo em acesso restrito.Rolling contact fatigue twin-disc tests were performed on rail/wheel steels from Spanish high velocity trains (AVE). Residual stress profiles were determined using X-ray diffraction before and after cyclic loading. The evolution of residual stress profiles, due to cyclic loading, was analysed in order to study how they affect the rolling contact fatigue behaviour of these materials. This study is included in a major project where other related phenomena and materials’ properties have been studied