• 대한금속재료학회지
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• 제47권9호
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• pp.573-579
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• 2009

Titanium/aluminum/stainless steel(Ti/Al/STS) clad materials have received much attention due to their high specific strength and corrosion-resisting properties. However, it is difficult to fabricate these materials, because titanium oxide is easily formed on the titanium surface during heat treatment. The aim of the present study is to derive optimized cladding conditions and thereupon obtain the stable quality of Ti/Al/STS clad materials. Ti sheets were prepared with and without pre-heat treatment and Ti/Al/STS clad materials were then fabricated by cold rolling and a post-heat treatment process. Microstructure of the Ti/Al and STS/Al interfaces was observed using a Scanning Electron Microscope(SEM) and an Energy Dispersed X-ray Analyser(EDX) in order to investigate the effects of Ti pre-heat treatment on the bond properties of Ti/Al/STS clad materials. Diffusion bonding was observed at both the Ti/Al and STS/Al interfaces. The bonding force of the clad material with non-heat treated Ti was higher than that with pre-heat treated Ti before the cladding process. The bonding force decreased rapidly beyond $400^{\circ}C$, because the formed Ti oxide inhibited the joining process between Ti and Al. Bonding forces of STS/Al were lower than those of Ti/Al, because brittle $Fe_3Al$, $Al_3Fe$ intermetallic compounds were formed at the interface of STS/Al during the cladding process. In addition, delamination of the clad material with pre-heat treated Ti was observed at the Ti/Al interface after a cupping test.

• 열처리공학회지
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• 제36권2호
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• pp.61-68
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• 2023

Ti and Ti alloys are used in the automobile and aerospace industries due to their high specific strength and excellent corrosion resistance. However their application is limited due to poor formability at room temperature and high unit cost. In order to overcome these issues, dissimilarly jointed materials, such as cladding materials, are widely investigated to utilize them in each industrial field because of an enhanced plasticity and relatively low cost. Among various dissimilar bonding processes, the rolled cladding process is widely used in Ti alloys, but has a disadvantage of low bonding strength. Although this problem can be solved through post-heat treatment, the mechanical properties at the bonded interface are deteriorated due to residual stress generated during post-heat treatment. Therefore, in this study, the microstructure change and residual stress trends at the interfaces of Ti/Al cladding materials were studied with increasing post-heat treatment temperature. As a result, compared to the as-rolled specimens, no difference in microstructure was observed in the specimens after postheat treatment at 300, 400, and 500℃. However, a new intermetallic compound layer was formed between Ti and Al when post-heat treatment was performed at a temperature of 600℃ or higher. Then, it was also confirmed that compressive residual stress with a large deviation was formed in Ti due to the difference in thermal expansion coefficient and modulus of elasticity between Ti Grade II and Al 1050.