The effect of plastic creep deformations of the interlayer during the TLP-bonding of high-temperature alloys on the formation of the stress-strain state of the nodes in the cooling process
Abstract
Matvienko M. V., Kvasnitsky V. V., Holub D. M. The effect of plastic creep deformations of the interlayer during the TLP-bonding of high-temperature alloys on the formation of the stress-strain state of the nodes in the cooling process // Herald of the DSEA. – 2019. – № 2 (46). – P. 22–28.
During thermal loading, accelerated cooling of nodes with a soft interlayer in a small area located near the interlayer at the butt edge and in the interlayer itself creates a complex SSS due to the difference between the CLTE of the metal to be joined and the interlayer. The method of computer simulation was used to study the formation of the stress-strain state of the nodes during the TLP-bonding of a heat-resistant alloy in the process of accelerated cooling, followed by exposure at a creep temperature. It was established that accelerated cooling with subsequent exposure for 540 s reduces stresses in the interlayer and in a small zone of the base metal near its edge due to short-term deformations and creep in the interlayer. At the same time, the degree of creep resistance of the interlayer compared to the base metal within the accepted limits (0.85 or 0.7) practically does not play a role. The resulting creep deformations have little effect on the nature of the stress field. Short-term plastic deformations in the variants with a smaller CLTE difference between the interlayer and the base metal and, accordingly, with a lower stress level, are small, they occur only in a small portion of the interlayer at the joint edge. At the same time, they are noticeably reduced compared with fast cooling as a result of stress reduction due to creep. In variants with a larger CLTE difference and, consequently, a higher level of stresses, short-term plastic deformations markedly increase and are distributed along the entire length of the interlayer. Compared with fast cooling, they are reduced slightly. Creep deformations with slow cooling followed by exposure appear and significantly exceed the level of short-term deformations in the variants with a small difference between the CLTE of the interlayer and the base metal. They change little when the creep resistance of the interlayer varies within accepted limits. The stiffness coefficients of the stress state, and accordingly, the degree of hardening and softening of the metal in the joint zone, with slow cooling, both in the base metal and in the interlayer, change slightly, mainly in small areas near the edge of the joint.
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