Research On Technology And Interfacial Characteristic Of Brazing YG6X Cemented Carbide To 40Cr Steel

Since the 21 st century, China’s lunar exploration project has developed rapidly. Complete the task of acquisiting regolith from the lunar surface to two meters deep below the surface. So the connection issue of carbide tool and steel substrate has become a key issue. The main issue in this article is to sovle the brazing between carbide tool with steel substrate. Explore tissue interface behavior of the joint. The theoretical basis can be provided for the design and the manufacture of the drill.The joints using vacuum brazing and BNi2 solder formed well. But M6 C brittle phase formed in the joints near the carbide alloy. And penetrate layer formed in the carbide alloy near the joints. M6 C brittle phase and the penetrate layer brittled the joints seriously.The typical microstructure of the joint which was got by using high frequency induction brazing and Ni-Cu-Si solder was: 40 Cr steel/ Fe-Co(s,s)/ FCC/element diffusion region /YG6 X. The typical microstructure of the joint by using Ni-Cr-Si solder was: 40 Cr steel/Fe-Ni(s,s)/Ni(s,s)+Cr5Si3/element diffusion region/YG6 X. The joint formed well using Ni-Co-Si solder. The typical microstructure of the joint was: 40 Cr steel/Fe-Ni-Co(s,s)/ element diffusion region/YG6 X.Since the joints was brittled seriously by using Ni-20Cu-10 Si and Ni-30Cu-10 Si solder, the joints splited when it cooled down. The most shear strength of the joint formed by Ni-10Cu-10 Si solder when it uninsulated was 171.1MPa. The most shear strength of the joint with the Ni-Cr-Si solder formed by Ni-5Cr-10 Si solder when it uninsulated was 332.2MPa. The most shear strength of the joint with the Ni-Co-Si solder formed by Ni-10Co-10 Si solder when it incubated 5min was 412.7MPa.The ratio of the number of the atom Co、Fe、Ni、Cu in the joint of Ni-10Cu-10 Si solder was nearly 1:1:3:2. The ratio of the number of the atom Co、Fe、Ni、Cu in the joint of Ni-20Cu-10 Si and Ni-30Cu-10 Si solder was nearly 1:1:1:1. High entropy alloy named by FCC in the joints formed more and more with the increasing of Cu. FCC caused serious lattice distortion and brittled the joints seriously. Cr5Si3 brittle organization was discoveryed in the joints by using Ni-Cr-Si solder. Cr5Si3 brittle organization formed more and more with the increasing of Cr. Cr5 x Si3z Cx+z brittle organization was discoveryed in the joints near YG6 X. It formed more and more with the increasing of Cr and the holding time. The Cr5 x Si3z Cx+z brittle organization brittled the joints seriously. Cr5Si3 brittle organization formed less used by Ni-5Cr-10 Si when the joint uninsulated and it dispersed in the joint. At the same time, Cr5 x Si3z Cx+z brittle organization in the joint disappeared and element diffusion region formed in the YG6 X near the joint. Co3W3 C brittle organization was discoveryed in the joints near the YG6 X by using Ni-20Co-10 Si solder. Co3W3 C brittle organization more and more with the increasing of the holding time. Many microcracks appeared in the Co3W3 C brittle organization when the joint cooled down. The microcracks brittled the joints seriously. Co3W3 C brittle organization was not found in the joint using Ni-10Co-10 Si solder. Element diffusion region formed in the YG6 X near the joint. When the joint incubated 5min, WC moved from YG6 X to the fiber seam and the shear strength of the joint increased. When the joint incubated 10 min, Many holes appeared by WC in the fiber seam which weakened the joint.