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International Journal of

Recent Trends in Engineering

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International Journal of Recent Trends in Engineering (IJRTE)

ISSN 1797-9617

Volume 1, Number 5, May 2009

Issue on Mechanical Engineering

Page(s): 93-99

Solid-State Diffusion Bonding of Commercially pure Titanium and Precipitation Hardening Stainless steel

Debasis Poddar

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Abstract

Solid-state direct diffusion bonding of commercially pure Titanium (Cp-Ti) and precipitation hardening stainless steel (PHSS) has been carried out in the temperature range of 800C to 1000C with an interval of 50C for 3.6 ks under 3.5 Mpa uniaxial load in (4 to 6)103 Pa vacuum. The effects of temperatures have been investigated with reference to bond strength. The examination revealed that the transition joints achieve tensile strength 108% and shear strength 87.6% higher compared to pure titanium. And the ductility of the joint has been found to be 12.8% when processed at 950C. The joint structure and intermetallic phases like Fe2Ti, FeTi, Cr2Ti, λ ( solid solution of Fe2Ti and Cr2Ti ), χ ( Fe17Cr7Ti5 ), α-Fe, α-Ti and β-Ti were predicted by optical microscope, SEM-BSE, EPMA and subsequently the presence of intermetallic phases including σ phase (compound of Fe and Cr ) were confirmed by X-ray diffraction (XRD) technique. EPMA also revealed substantial diffusion of Fe, Cr and Ni into the titanium base-metal and titanium traveled a less distance towards PHSS side. Bond strength and hardness of the interface layers were measured by tensile testing and micro-hardness testing respectively. The activation energy Q and growth velocity k of the reacting layers in the diffusion bonded joints were also calculated. The bond strength has been found to be satisfactory at 950C. Bond strength drops as the volume fraction of intermetallics increased with the rise in bonding temperature (1000C).

Index Terms

Diffusion bonding, Intermetallics, SEM-BSE, EPMA, X-ray diffraction.

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