The effect of the yield strength of the interlayer on the stress-strain state of the nodes during diffusion welding and brazing of a heat-resistant alloy, taking into account the plastic deformations of materials during rapid cooling
Abstract
Matvienko M. V., Kvasnitsky V. F., Makarenko N. O. The effect of the yield strength of the interlayer on the stress-strain state of the nodes during diffusion welding and brazing of a heat-resistant alloy, taking into account the plastic deformations of materials during rapid cooling // Herald of the DSEA. – 2019. – № 2 (46). – Р. 29–34.
In this work, using computer simulation, the stress-strain state (SSS) under the action of thermal load of cylindrical samples with soft layers that have a lower yield strength than the base metal was investigated. It has been established that in a small zone of the base metal near the outer surface at the junction with the interlayer and in the interlayer itself there arises a complex SSS with radial, axial, circumferential and tangential stresses. Volumetric SSS due to the difference between the CLTE of the interlayer and the base metal is created only in the interlayer along its entire length and in small areas with a length of no more than 10 interlayer thickness, in the base metal near the outer edge of the interlayer. Depending on the degree of “softness” of the interlayer, the stress level changes. The change in the yield strength of the interlayer within 0.75 ... 0.85 of the yield strength of the base metal has little effect on the distribution pattern and magnitude of the stresses in the zone of the volumetric SSS, only the length of this zone changes, which is about 5 thicknesses of the interlayer. The appearance of plastic de-formations in the interlayer has little effect on the stiffness coefficient of the stress state and the degree of hardening or softening of both the base metal and the interlayer material. At the joint edge, the metal is strengthened somewhat more than in the elastic problem. The softening of the metal in the middle part of the joint when the temperature changes (thermal cycling) should favorably influence the formation of a joint in the zone of deformation stagnation during diffusion welding. The temperature change (thermal cycling) contributes to the formation of a joint in the zone of deformation stagnation during diffusion welding. The change in the value of the yield strength and CLTE of the layer in the accepted limits practically do not play a role. The softening of the base metal in the middle part of the joint and the interlayer near its edge must be taken into account when designing such assemblies and choosing the properties of the interlayer material.
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