Origin and development of residual stresses induced by laser surface-hardening treatments

The variations of residual stresses and microstructures obtained by surface hardening with a 15-kW, continuous-wave CO sub 2 laser on samples of AISI 1045 (C43) and AISI 4140 (40CD4) have been studied. From residual stress measurements, it is found that the stresses in the more superficial layers ma...

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Bibliographic Details
Published in:Journal of heat treating 1984-06, Vol.3 (3), p.193-204
Main Authors: SOLINA, A, SANCTIS, M. de, PAGANINI, L, BLARASIN, A, QUARANTA, S
Format: Article
Language:English
Subjects:
Applied sciences
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Hardening. Tempering
Heat treatment
Materials science
Metals, semimetals and alloys
Metals. Metallurgy
Physics
Production techniques
Specific materials
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Summary:The variations of residual stresses and microstructures obtained by surface hardening with a 15-kW, continuous-wave CO sub 2 laser on samples of AISI 1045 (C43) and AISI 4140 (40CD4) have been studied. From residual stress measurements, it is found that the stresses in the more superficial layers may vary, with changing laser operating conditions, from compressive stress values ( > 200 MPa) to strong tensile stress values (up to approx +800 MPa). The max. temp. reached during laser treatment, the depth of heating and the boundary conditions imposed influence the residual stress state. It seems possible to limit the onset of tensile stress states at the surface or even to obtain a compressive stress state by heating the material for relatively long periods of time (0.5 to 1.5 s) and by avoiding high surface temp. Some preliminary tests involving suitably programed repeated treatments of samples seem to indicate that improved combinations of the depth of hardening, the characteristics of the martensite and the state of the residual stress can be obtained. To account for the experimental results, hypotheses have been advanced to explain the stress evolution during laser heating cycles. 17 ref.--AA
ISSN:0190-9177
DOI:10.1007/BF02833261