Effect of high-temperature brazing with a nickel-based STEMET 1301A brazing alloy on the unbrazing temperature of 12Kh18
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ORIGINAL ARTICLE
Effect of high-temperature brazing with a nickel-based STEMET 1301A brazing alloy on the unbrazing temperature of 12Kh18N10T steel joints А. Ivannikov 1 & E. Krasnova 1 & М. Penyaz 1 & N. Popov 1 & А. Melnikov 1,2 & O. Sevryukov 1 Received: 27 April 2020 / Accepted: 27 July 2020 / Published online: 22 August 2020 # Springer-Verlag London Ltd., part of Springer Nature 2020
Abstract The challenges facing the creation of brazed joints of 12Kh18N10T (AISI 321) austenitic stainless steel with high unbrazing temperatures for extreme working conditions in aerospace appliances are considered in this study. An amorphous-nanocrystalline nickel–based foil, Ni-7Cr-4.5Si-3.5Fe-2.6B, wt.%, is used for brazing the steel. Experiments on brazing regimes with various temperatures (1070–1160 °С) and times of exposition (15–80 min) are carried out. The formation of Ni-based solid solutions with different Cr, Fe, Mn, Si, and Ti contents in the brazed seam is detected for all brazing regimes. Using Thermo-Calc software, the liquidus temperature located in a range between 1268 and 1388 °С is calculated. To verify the calculated values, the unbrazing temperature is experimentally determined for specimens, with a composition of the solid solutions, formed in the center of the brazed seam during brazing at 1160 °С/15 min, 1070 °С/15, and 1160 °С/80 min. The experimental results deviate from values computed by Thermo-Calc by no more than 54 °С. The experimental samples obtained using the 1070 °C/40 min and 1100 °C/ 80 min regimes demonstrate high unbrazing temperatures equal to 1303 °C and > 1330 °C, respectively, which corresponds to the calculations with an accuracy of 2.5%. Taking into account the combination of properties (strength and unbrazing temperature), brazing regimes of heating to 1070–1100 °C and an exposure time for 15–40 min can be recommended for the production of high-strength joints with high unbrazing temperatures. Keywords Filler metal . BNi-2 . Austenitic stainless steel . Diffusion brazing . TLP bonding . Joint . Unbrazing . Thermo-Calc
1 Introduction The capability of forming a joint at a temperature below the melting temperature of brazing materials is the main advantage of the brazing technological process. Joining of dissimilar materials or joining of three or more sheets of material requires combining different joining technologies. Welding technologies face challenges, such as local melting during the welding process and determining the optimal process parameters [1–3]. Brazing is often used to create multiple joints in a single process cycle instead of welding [4, 5]. High-
* N. Popov [email protected] 1
National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe highway 31, Moscow 115409, Russia
2
NPO “TSNIITMASH”, Sharikopodshipnikovskaya st. 4, Moscow 115088, Russia
temperature brazing has been widely used to create structures such as heat exchangers, filters, honeycomb structures, liquid rocket engine nozzles, and many others [6–8]. Nowadays, steel is th
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