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Abstract
This paper outlines the optimisation of vacuum brazing conditions for joining titanium stabilised Stainless Steel SS321 sheets by Ni-based braze alloy (Ni-Mn-Cr-Co-Si) as brazing filler metal (BFM) for two shelled rocket nozzle applications. This is a specialized brazing technique in which multiple parameters such as temperature, time, argon pressure in the furnace and vacuum level in the channels between the shells are to be precisely controlled in a complex furnace. Brazing temperature, holding time, surface pressure in terms of dead weight and vacuum levels were identified as parameters having significant effect on the bonding strength of a braze joint. Taguchi method was used as a statistical technique for design of experiments to optimise brazing conditions in terms of shear strength. L9(34 ) orthogonal array was designed for conducting the experiments with four parameters at three levels ie temperature (1190oC, 1230oC,1270oC), holding time (10min, 20min, 30min), surface pressure (100kPa, 150kPa, 200kPa) and vacuum level (0.133Pa, 1.33Pa, 13.3Pa). The optimised set of parameters ie temperature: 1230oC, time: 20min, pressure: 100kPa, vac. level: 1.33Pa has been arrived at by Taguchi method via statistical analysis through analysis of means (AVOM) and analysis of variances (ANOVA). Confirmatory test for optimised conditions agreed well with the Taguchi analysis. Also, extensive optical metallography and energy dispersion X-ray analysis across the joint were carried out to study the metallographic morphology across the joint. The fractured surfaces during lap shear tensile testing have also been studied under SEM.
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References
- Daniel Kay, W., "Ten Reasons to Choose Brazing", Welding Journal, Sep. 2000, pp.33-55.
- Yoshiaki Arata., Akira Ohmori and Huai Fu Cai., "Studies on Vacuum Brazing (Report II)", Transactions of Journal of Welding Research Institute, Japan, 1983.
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- Ljungberg, L., Warren, R. and Li, C.H., "A Novel method for Identifying Phases Formed in Brazed and Soldered Joints", Journal of Material Science, Letters 9, 1990, pp.1316-1318.
- Phillip J. Ross., "Taguchi Technique for Quality Engineering", Tata McGraw Hill, Second Edition, 2005, pp.91-179.
- Wei Li., Jack Hu, S. and Shao-wei Cheng., "Robust Design and Analysis for Manufacturing Processes with Parameters Interdependency", Journal of Manufacturing Systems, 10/21/2, 2002, pp.93-100.
- Gaitonde, V.N., Karnik, S.R. and Paulo Darvim, J., "Taguchi Multiple - Performance Characteristics Optimization in Drilling of Medium Density Fibreboard (MDF) to Minimize Delamination Using Utility
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- Wang Jaun., Li Yajiang., Liu Perg and Geng Haoran., "Microstructure and XRD Analysis in the Interface
- Zone of Mg/Al Diffusion Bonding", Journal of Material Processing Technology 205, 2008, pp.146-
- Ivanor, A.D., Knestnikor, N.S., Yu V. Blinor., Barysher, M.S. and Ye I. Chulkor., "Microscopic Observation and Mechanical Tests of CuNiCrSi/321 Brazed Joints", Plasma Device and Operations, Vol.6:1, 1998, pp.37-44.
- Mandal, S. and Ray, A.K., "Correlation Between the Mechanical Properties and Microstructural Behaviour of Al2O3 - (Ag-Cu-Ti) Brazed Joint", Mater. Sci. Engg , Vol. 383, No. 2, 2004, pp.235-244..
References
Daniel Kay, W., "Ten Reasons to Choose Brazing", Welding Journal, Sep. 2000, pp.33-55.
Yoshiaki Arata., Akira Ohmori and Huai Fu Cai., "Studies on Vacuum Brazing (Report II)", Transactions of Journal of Welding Research Institute, Japan, 1983.
Yi Qi Wang., Ali Md. Afsar and Jung II Song., "Optimisation of Brazing Conditions for OFHC Cu and ASTM A501 Low Carbon Steel by Taguchi Method", International Journal of Precision Engineering and Manufacturing, Vol.10, No.3, pp.97104, July 2009.
Yue, X., He, P., Feng, J.C., Zhang, J.H. and Zhu, F.Q., "Microstructure and Interfacial Reactions of Vacuum Brazing Titanium Alloy to Stainless Steel Using an AgCuTi Filler Metal", Materials Characterization 59, pp.1721-1727.
Ljungberg, L., Warren, R. and Li, C.H., "A Novel method for Identifying Phases Formed in Brazed and Soldered Joints", Journal of Material Science, Letters 9, 1990, pp.1316-1318.
Phillip J. Ross., "Taguchi Technique for Quality Engineering", Tata McGraw Hill, Second Edition, 2005, pp.91-179.
Wei Li., Jack Hu, S. and Shao-wei Cheng., "Robust Design and Analysis for Manufacturing Processes with Parameters Interdependency", Journal of Manufacturing Systems, 10/21/2, 2002, pp.93-100.
Gaitonde, V.N., Karnik, S.R. and Paulo Darvim, J., "Taguchi Multiple - Performance Characteristics Optimization in Drilling of Medium Density Fibreboard (MDF) to Minimize Delamination Using Utility
Concept", J. Mater. Process. Techno., Vol.196, No.1- 3, pp.51- 53, 2008.
Wang Jaun., Li Yajiang., Liu Perg and Geng Haoran., "Microstructure and XRD Analysis in the Interface
Zone of Mg/Al Diffusion Bonding", Journal of Material Processing Technology 205, 2008, pp.146-
Ivanor, A.D., Knestnikor, N.S., Yu V. Blinor., Barysher, M.S. and Ye I. Chulkor., "Microscopic Observation and Mechanical Tests of CuNiCrSi/321 Brazed Joints", Plasma Device and Operations, Vol.6:1, 1998, pp.37-44.
Mandal, S. and Ray, A.K., "Correlation Between the Mechanical Properties and Microstructural Behaviour of Al2O3 - (Ag-Cu-Ti) Brazed Joint", Mater. Sci. Engg , Vol. 383, No. 2, 2004, pp.235-244..