High-temperature brazing of molybdenum to 12Cr18Ni10Ti steel with the CTEMET 1301 rapidly quenched nickel brazing alloy

Abstract

Extensive studies are being carried out to develop a divertor (Divertor: a device in a thermonuclear reactor, intended for receiving of particle flows and radiation from the periphery of the plasma column. It is the most heavily loaded part of the reactor chamber surfaces with energy fluxes.) for tokamaks with a container for supplying liquid metal to the reception surface, with the construction of actual structures with high reliability and long service life. In this case, it is necessary to develop methods for joining dissimilar materials. In the transition section, molybdenum and steel (12Cr18Ni10Ti) pipes are joined by brazing. In this work, the method of producing a strong, heat resisting and hermetic joint between molybdenum and 12Cr18Ni10Ti corrosion-resisting steel is developed. Brazing is carried out using a paste based on CTEMET-1301 brazing alloy. The method of assembling the components in order to produce optimum gaps in brazing resulting in the homogeneous brazed joint without the formation of a brittle eutectic interlayer is developed. The brazed specimens were tested for heat resistance, leak tightness and service life at the given load. All the specimens withstood the tests. The mechanical properties of the brazed joints were determined by measuring the microhardness of the region of the welded joint and by shear tests. The results show that the strength characteristics depend strongly on the size of the gap between the brazed components. For the specimens assembled with the optimum gap the ultimatum shear strength was 500 ± 50 MPa.