Effect of a copper filler metal on the microstructure and mechanical properties of electron beam welded titanium-stainless steel joint

Journal Article · Thu Nov 15 00:00:00 EST 2012 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2012.08.004· OSTI ID:22163149

Wang, Ting ^[1]; Zhang, Binggang ^[2]; Feng, Jicai ^[1]; Tang, Qi ^[2]

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1. Key Laboratory of Special Welding in Shandong Province, Harbin Institute of Technology at Weihai, Weihai, 264209 (China)
2. State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin, 150001 (China)

Cracking in an electron beam weld of titanium to stainless steel occurred during the cooling process because of internal thermal stress. Using a copper filler metal, a crack free joint was obtained, which had a tensile strength of 310 MPa. To determine the reasons for cracking in the Ti/Fe joint and the function of the copper filler metal on the improvement of the cracking resistance of the Ti/Cu/Fe joint, the microstructures of the joints were studied by optical microscopy, scanning electron microscopy and X-ray diffraction. The cracking susceptibilities of the joints were evaluated with microhardness tests on the cross-sections. In addition, microindentation tests were used to compare the brittleness of the intermetallics in the welds. The results showed that the Ti/Fe joint was characterized by continuously distributed brittle intermetallics such as TiFe and TiFe(Cr){sub 2} with high hardness ({approx} 1200 HV). For the Ti/Cu/Fe joint, most of the weld consisted of a soft solid solution of copper with dispersed TiFe intermetallics. The transition region between the weld and the titanium alloy was made up of a relatively soft Ti-Cu intermetallic layer with a lower hardness ({approx} 500 HV). The formation of soft phases reduced the cracking susceptibility of the joint. - Highlights: Black-Right-Pointing-Pointer Electron beam welded Ti/Fe joint cracked for the brittleness and residual stress. Black-Right-Pointing-Pointer Electron beam welded Ti/Cu/Fe joint with tensile strength of 310 MPa was obtained. Black-Right-Pointing-Pointer Cu diluted Ti and Fe contents in weld and separated the TiFe{sub 2} into individual blocks. Black-Right-Pointing-Pointer Interfacial hard Ti-Fe compounds were replaced by soft Ti-Cu compounds in the weld. Black-Right-Pointing-Pointer A large amount of solid solution of copper formed in the weld.

• OSTI ID: 22163149
• Journal Information: Materials Characterization, Vol. 73, Issue Complete; Other Information: Copyright (c) 2012 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1044-5803
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BRITTLENESS
COPPER
CROSS SECTIONS
ELECTRON BEAMS
FILLER METALS
MICROHARDNESS
MICROSTRUCTURE
OPTICAL MICROSCOPY
RESIDUAL STRESSES
SCANNING ELECTRON MICROSCOPY
SOLID SOLUTIONS
STAINLESS STEELS
TENSILE PROPERTIES
THERMAL STRESSES
TITANIUM
TITANIUM ALLOYS
WELDED JOINTS
X-RAY DIFFRACTION