A stainless steel clad plate composed of stainless steel and carbon steel was prepared by vacuum hot rolling process, and its microstructure, especially the bonding interface, was evaluated using an optical microscope...A stainless steel clad plate composed of stainless steel and carbon steel was prepared by vacuum hot rolling process, and its microstructure, especially the bonding interface, was evaluated using an optical microscope, a scanning electron micro- scope and a transmission electron microscope （TEM）. The corresponding mechanical properties were also assessed by means of hardness and shear tests. The results showed a bonding interface formed between stainless steel and carbon steel, which was relatively straight in macroscope but serrated in microscope. Decarburization layer and carbon-enriched layer were distinguished at the side of carbon steel and stainless steel near the interface, respectively, which should be related to diffusion of carbon and alloying elements. The carbon-enriched layer could also be identified as a recombination region, whose microstructure was mainly recognized as martensite by TEM. Consequently, the hardness was the highest at this region. Furthermore, the result of shear test at the bonding interface showed that the shear strength was 395 MPa and the fracture mode was dominated as ductile fracture, indicating the bonding interface with good quality.展开更多
Vacuum hot roll bonding （VHRB） was used to bond pure titanium （Ti） plate to a 304 stainless steel （SS） plate with a niobium （Nb） interlayer, with the aim of producing a high-quality Ti-SS clad plate. The roll-...Vacuum hot roll bonding （VHRB） was used to bond pure titanium （Ti） plate to a 304 stainless steel （SS） plate with a niobium （Nb） interlayer, with the aim of producing a high-quality Ti-SS clad plate. The roll-bonding process was performed at different temperatures in the range of 850-1000℃, followed by characterization of microstructure and mechanical properties. The study demonstrates that the interfaces are free from cracks and discontinuities, and interdiffusion between the stainless steel and the titanium is effectively prevented by inserting a layer of pure Nb foil. No intermetallic reaction layer occurred at the Nb-Ti interface at any of the investigated temperatures. An intermetallic FeNb phase was formed at the Nb-SS interface when bonding was performed at 950 ℃ and above. The presence of the FeNb layer was confirmed by x-ray diffraction. The maximum shear strength of -396 MPa was obtained when bonding is carried out at 900 ℃. However, the formation of the FeNb layer at roll bonding temperature greater than 900 ℃ led to decrease in shear strength. Ductile fracture occurred through the Ti-Nb interface for roll-bonded temperatures of up to 900 ℃. On the other hand, at temperature of 950℃ and above, failure occurred through the Nb-SS interface, with brittle fracture characteristics.展开更多
文摘A stainless steel clad plate composed of stainless steel and carbon steel was prepared by vacuum hot rolling process, and its microstructure, especially the bonding interface, was evaluated using an optical microscope, a scanning electron micro- scope and a transmission electron microscope （TEM）. The corresponding mechanical properties were also assessed by means of hardness and shear tests. The results showed a bonding interface formed between stainless steel and carbon steel, which was relatively straight in macroscope but serrated in microscope. Decarburization layer and carbon-enriched layer were distinguished at the side of carbon steel and stainless steel near the interface, respectively, which should be related to diffusion of carbon and alloying elements. The carbon-enriched layer could also be identified as a recombination region, whose microstructure was mainly recognized as martensite by TEM. Consequently, the hardness was the highest at this region. Furthermore, the result of shear test at the bonding interface showed that the shear strength was 395 MPa and the fracture mode was dominated as ductile fracture, indicating the bonding interface with good quality.
基金financially supported by the Fundamental Research Funds for Chinese Central Universities(No.N110607001)National High Technical Research and Development Programme of China(No.2013AA031302)
文摘Vacuum hot roll bonding （VHRB） was used to bond pure titanium （Ti） plate to a 304 stainless steel （SS） plate with a niobium （Nb） interlayer, with the aim of producing a high-quality Ti-SS clad plate. The roll-bonding process was performed at different temperatures in the range of 850-1000℃, followed by characterization of microstructure and mechanical properties. The study demonstrates that the interfaces are free from cracks and discontinuities, and interdiffusion between the stainless steel and the titanium is effectively prevented by inserting a layer of pure Nb foil. No intermetallic reaction layer occurred at the Nb-Ti interface at any of the investigated temperatures. An intermetallic FeNb phase was formed at the Nb-SS interface when bonding was performed at 950 ℃ and above. The presence of the FeNb layer was confirmed by x-ray diffraction. The maximum shear strength of -396 MPa was obtained when bonding is carried out at 900 ℃. However, the formation of the FeNb layer at roll bonding temperature greater than 900 ℃ led to decrease in shear strength. Ductile fracture occurred through the Ti-Nb interface for roll-bonded temperatures of up to 900 ℃. On the other hand, at temperature of 950℃ and above, failure occurred through the Nb-SS interface, with brittle fracture characteristics.
