Roll‐Bonded Titanium/Stainless‐Steel Couples, Part 1: Diffusion and Interface‐Layer Investigations

Abstract

Cold roll bonding of dissimilar metals (two or more material layers) is a well-known, cold, pressure-welding process and provides great advantages in comparison to single alloys for a variety of applications. It allows various material properties (optical, mechanical, thermal, chemical or electromagnetic) to be combined, which a single material cannot achieve. One example for the application of this technique is the bonding of wear-resistant parts where a high-strength material is bonded onto softer base materials. Depending on the requirement, 3 or 5 layers are no rarity. The manufacturing industry faces the challenge of increasing demands on material characteristics, which can only be satisfied by developing new clad material combinations. In this first of two papers, diffusion phenomena of alloying elements and the corresponding interface-layer formation are the focus of the investigation. In a further paper, the mechanical properties of the investigated material couple will be presented. As a first step, the diffusion profiles after different heat treatments were determined by means of electron probe microanalysis (EPMA) investigations. They provide an insight into the quantitative (line-scans) and qualitative (element-distribution mapping) local chemical composition in the interface region. In the second stage, the diffusion coefficients and activation energies were calculated based on the EPMA results. Finally, the observed interface layers were characterized by means of LOM and SEM pictures which were correlated to the EPMA line-scan results.

Roll‐Bonded Titanium/Stainless‐Steel Couples. Part 3: Adhesion Properties

“…After a heat treatment at 700 8C for 5 and 10 min only a b-titanium layer can be detected in the interface area ( Figure 11). As already described in Ref., [7] after a heat treatment of 750 and 800 8C (10 min) beside the b-titanium the intermetallic layers s-and FeTi-phase can be detected ( Figure 12). …”

“…The examination of the micrographs of the interface after different heat treatments in ref. [7] shows that the intermetallic layers s-and FeTi-phase retain a constant layer thickness of 1-2 mm independent of the annealing temperature. The above located b-titanium layer is growing continuously with rising annealing temperature.…”

“…Micrographs from the interface after a heat treatment of 10 min at 750 (left) and 800 8C (right). [7] Fig. 13.…”

“…A non-destructive method is the measurement of the electrical resistance. [5,6] With metallographic images of the interface and the evaluation of areas of fraction, [7,8] an evaluation of the quality of the adhesion for the investigated titanium-austenite material couple could be already given. The determination of quantitative data for the bond strength can be realized with tensile shear and peeling tests.…”

Steel-Based Composites: Driving Forces and Classifications

“…Although the majority of explosively clad steels are used in large reactor vessels, there is considerable interest in developing alternative methods of manufacture and extensive recent work on roll-bonded titanium/stainless steel sheets (14). For thin coatings of materials such as tantalum, processes such as pulsed laser deposition (PVD) methods, sputter deposition, and electrodeposition using a molten salt electrolyte have been developed (15).…”