National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Russia, Moscow:

M. A. Penyaz, Post-Graduate Student, Department №9 “Physical problems of materials science”, e-mail: mapenyaz@mephi.ru
A. A. Ivannikov, Senior Lecturer, Department №9 “Physical problems of materials science”, e-mail: ivannikov7@rambler.ru
B. A. Kalin, Professor, Department №9 “Physical problems of materials science”, e-mail: bakalin@mephi.ru
P. S. Dzhumaev, Associate Professor, Department №9 “Physical problems of materials science”, e-mail: psdzhumaev@mephi.ru

The article was attended by the staff of the Department №9 “Physical problems of materials science” NRNU MEPhI – Sevryukov O. N., Suchkov A. N., Fedotov I. V.

Demands on the properties of constructions are constantly being increased and the technology of producing permanent joints is crucial for advancement of the high-tech industry. This investigation focuses on thermal fatigue of austenitic steel joints, brazed with nickel filler metals based on Ni – Cr – Si system. This type of fatigue has nonmechanical origin and arises from the cyclic variation of thermal stresses with temperature changes. For investigation selected temperature range is: from room temperature to 450 ^oC (low-cycle fatigue). Due to inhomogeneous thermal expansion or compression during thermal fatigue, thermal stresses and deformation arise and lead to microstructural changes in the joint zone. This can have a strong effect on the mechanical characteristics of the joint. Therefore, it is important to investigate the properties of the brazed seam after thermal cycling. In this work samples brazed various filler metals before and after thermocycling were evaluated using various methods. The microstructures were investigated and analysis by energy-dispersive X-ray spectroscopy (EDS) of the diffusion zone was carried out using electron microscope. The main regularities of the structure-phase state formation studied using electron backscatter diffraction (EBSD). Standard tests for the tensile strength of the samples were carried out. The result of this research is the prediction of the durability and reliability of brazed steel constructions operating under conditions of low-cycle temperature changes.

The reported study was funded by RFBR and DFG according to the research project №19-52-12030.
This work was supported by the MEPhI Academic Excellence Project.

1. Liu Z. P., Zhou G.-Y., Tian F. Q., Chen D. Q., Tu S.-T. Experimental Investigation on the Kinetic Parameters of Diffusion Component for Vacuum Brazing SS316L/BNi-2/SS316L Joint. Procedia Engineering. 2015. Vol. 130. pp. 497–508. DOI: 10.1016/j.proeng.2015.12.246.
2. Gu X. L., Yang C. J., Chen Z. J., Wu C. D., Feng L. L. Effect of Temperature on Microstructure and Mechanical Properties of 316L Stainless Steel Brazed Joints. Advanced Materials Research. 2011. Vol. 418–420. pp. 1494–1497. DOI: 10.4028/www.scientific.net/amr.418-420.1494.
3. Ivannikov A. A., Tukhbatov V. A., Suchkov A. N., Ustyuzhaninov A. L., Bogachev I. A. Rapidly quenched nickel based filler metal for high temperature various constructive elements brazing. Tsvetnye Metally. 2014. No. 12. pp. 27–31.
4. Binesh B., Jazayeri Gharehbagh A. Transient Liquid Phase Bonding of IN738LC/MBF-15/IN738LC: Solidification Behavior and Mechanical Properties. Journal of Materials Science & Technology. 2016. Vol. 32, Iss. 11. pp. 1137–1151. DOI: 10.1016/j.jmst.2016.07.017.
5. Hartmann T., Marsilius M. Influence of Boron and Phosphor Containing Nickel Based Brazing Alloy on Different Base Materials. LÖT 2016: 11^th International Conference on Brazing, High Temperature Brazing and Diffusion Bonding, June 7^th to 9^th, 2016, Aachen, Germany. 2016. DVS-Berichte, Bd. 325. pp. 227–232.
6. Xia C., Sun W., Zhou Y., Xu X. Thermal fatigue damage and residual mechanical properties of W – Cu/Ag – Cu/1Cr18Ni9 brazed joint. Journal of Alloys and Compounds. 2018. Vol. 741. pp. 155–160. DOI: 10.1016/j.jallcom.2018.01.151.
7. de Prado J., Sánchez M., Wirtz M., Pintsuk G., Du J., Linke J., Ureña A. Impact of thermal fatigue on W–W brazed joints for divertor components. Journal of Materials Processing Technology. 2018. Vol. 252. pp. 211–216. DOI: 10.1016/j.jmatprotec.2017.09.024.
8. Bachurina D., Suchkov A., Kalin B., Sevriukov O., Fedotov I., Dzhumaev P., Ivannikov A., Leont’eva-Smirnova M., Mozhanov E. Joining of tungsten with low-activation ferritic–martensitic steel and vanadium alloys for demo reactor. Nuclear Materials and Energy. 2018. Vol. 15. pp. 135–142. DOI: 10.1016/j.nme.2018.03.010.
9. Bachurina D., Suchkov A., Filimonov A., Fedotov I., Savelyev M., Sevryukov O., Kalin B. High-temperature brazing of tungsten with steel by Cu-based ribbon brazing alloys for DEMO. Fusion Engineering and Design. 2019. DOI: 10.1016/j.fusengdes.2019.02.072.
10. Das A. Cyclic plasticity induced transformation of austenitic stainless steels. Materials Characterization. 2019. Vol. 149. pp. 1–25. DOI: 10.1016/j.matchar.2018.12.002.
11. M. Sistaninia, M. Niffenegger, Fatigue crack initiation and crystallographic growth in 316L stainless steel. International Journal of Fatigue. 2015. Vol. 70. pp. 163–170. DOI: 10.1016/j.ijfatigue.2014.09.010.
12. ASM Handbook: Fatigue and Fracture, Vol. 19. ASM International. Handbook Committee, 1996.
13. Ivannikov A. A., Kalin B. A., Sevryukov O. N., Penyaz M. A., Fedotov I. V., Misnikov V. E., Tarasova M. S. Study of the Ni – Si – Be system as a base to create boron-free brazing filler metals. Science and Technology of Welding and Joining. 2017. Vol. 23, Iss. 3. pp. 187–197. DOI: 10.1080/13621718.2017.1361668.
14. Metal Science: a manual in 2 vol. Vol. 2. Heat treatment. Alloys. Ed. by V. S. Zolotarevsky. 2^nd ed., rev. Moscow : Izdatelskiy dom MISiS, 2014. 528 p.
15. GOST-28830–90. Soldered and brazed joints. Test methods for tension and long-term strength. Publication date: 01.01.92. Moscow: IPK Izdatelstvo standartov, 2005.
16. Rabinkin A. Brazing with (NiCoCr) – B – Si amorphous brazing filler metals: alloys, processing, joint structure, properties, applications. Science and Technology of Welding and Joining. 2004. Vol. 9, Iss. 3. pp. 181–199. DOI: 10.1179/136217104225012300.
17. Baak N., Garlich M., Schmiedt A., Bambach M., Walther F. Characterization of residual stresses in austenitic disc springs induced by martensite formation during incremental forming using micromagnetic methods. Materials Testing. 2017. Vol. 59, Iss. 4. pp. 309–314. DOI: 10.3139/120.111012.
18. Eskandari M., Najafizadeh A., Kermanpur A. Effect of strain-induced martensite on the formation of nanocrystalline 316L stainless steel after cold rolling and annealing. Materials Science and Engineering: A. 2009. Vol. 519, Iss. 1-2. pp. 46–50. DOI: 10.1016/j.msea.2009.04.038.