Green and low carbon promote the application and development of light-weight materials in body-in-white. Large-scale die-casting Al alloy (DCAA) and high-strength thermo-formed steel sheet (TFSS) have put forward high...Green and low carbon promote the application and development of light-weight materials in body-in-white. Large-scale die-casting Al alloy (DCAA) and high-strength thermo-formed steel sheet (TFSS) have put forward higher requirements for the application of joining technology of high-strength steel/Al dissimilar materials. Taking the new die-casting Al alloy body as an example, this paper systematically studies the progress of the latest joining methods of steel/Al dissimilar material with combination of two-layer plate and three-layer plate. By analyzing the joining technologies such as FSPR, RES, FDS and SPR, the technology and process characteristics of steel/Al dissimilar material joining are studied, and the joining technical feasibility and realization means of different material combination of the body are analyzed. The conditions of material combination, material thickness, material strength, flange height, preformed holes and joint spacing for achieving high-quality joining are given. The FSPR joining technology is developed and tested in order to meet with the joining of parts with DCAA and TFSS, especially for the joining of three-layer plates with them. It finds the method and technical basis for the realization of high quality joining of dissimilar materials, provides the early conditions for the application of large DCAA and TFSS parts in body-in-white, and meets the design requirements of new energy body. .展开更多
The crack-free Ni60 A coating was fabricated on 45 steel substrate by laser cladding and the microstructure including solidification characteristics, phases constitution and phase distribution was systematically inves...The crack-free Ni60 A coating was fabricated on 45 steel substrate by laser cladding and the microstructure including solidification characteristics, phases constitution and phase distribution was systematically investigated. The high temperature friction and wear behavior of the cladding coating and substrate sliding against GCr15 ball under different loads was systematically evaluated. It was found that the coating has homogenous and fine microstructure consisting of γ（Ni） solid solution, a considerable amount of network Ni-Ni3 B eutectics, m^23C6 with the floret-shape structure and Cr B with the dark spot-shape structure uniformly distributing in interdendritic eutectics. The microhardness of the coating is about 2.6 times as much as that of the substrate. The coating produces higher friction values than the substrate under the same load condition, but the friction process on the coating keeps relatively stable. Wear rates of the coating are about 1/6.2 of that of the substrate under the higher load（300 g）. Wear mechanism of the substrate includes adhesion wear, abrasive wear, severe plastic deformation and oxidation wear, while that of the coating is merely a combination of mild abrasive wear and moderate oxidation wear.展开更多
Hot compression tests were performed to investigate the hot deformation behavior of Fe–27.34Mn–8.63Al–1.03C lightweight steel and optimize the hot workability parameters. The temperature range was 900–1150℃ and t...Hot compression tests were performed to investigate the hot deformation behavior of Fe–27.34Mn–8.63Al–1.03C lightweight steel and optimize the hot workability parameters. The temperature range was 900–1150℃ and the strain rate range was 0.01–5 s^(-1)on a Gleeble-3800 thermal simulator machine. The results showed that the flow stress increased with decreasing deformation temperature and increasing strain rate. According to the constitutive equation, the activation energy of hot deformation was 422.88 kJ·mol^(-1). The relationship between the critical stress and peak stress of the tested steel was established, and a dynamic recrystallization kinetic model was thus obtained. Based on this model, the effects of strain rate and deformation temperature on the volume fraction of dynamically recrystallized grains were explored. The microstructural examination and processing map results revealed that the tested steel exhibited a good hot workability at deformation temperatures of 1010–1100℃ and strain rate of 0.01 s^(-1).展开更多
A binary Fe-Al alloyed layer was synthesized on 45 steel by means of double glow plasma surface alloying technique. The corrosion-resisting layer prepared is composed of a sedimentary layer and a diffusion layer, with...A binary Fe-Al alloyed layer was synthesized on 45 steel by means of double glow plasma surface alloying technique. The corrosion-resisting layer prepared is composed of a sedimentary layer and a diffusion layer, with a total thickness of about 180 μm. The aluminum content of the alloyed layer shows gradual change from surface to the inside of substrate. The ideal profile is beneficial to the metallurgical bonding of the surface alloying layer with substrate materials. The microstructure of both layers consists of the Fe-Al intermetallic compound, which is FeAl with B2 structure in the sedimentary layer and Fe3Al with incompletely ordered DO3 structure in the diffusion layer. The protective film exhibits high micro-hardness. In comparison with the substrate of 45 steel, the corrosion resistance of the aluminized sample is much higher in 2.0% Na2S and 0.05 mol/L Na2SO4 + 0.5 mol/L NaCl mixed solutions.展开更多
Effects of laser pulse distance and reinforcing of 5456 aluminum alloy were investigated on laser weldability of Al alloy to duplex stainless steel (DSS) plates. The aluminum alloy plate was reinforced by nickel-base ...Effects of laser pulse distance and reinforcing of 5456 aluminum alloy were investigated on laser weldability of Al alloy to duplex stainless steel (DSS) plates. The aluminum alloy plate was reinforced by nickel-base BNi-2 brazing powder via friction stir processing. The DSS plates were laser welded to the Al5456/BNi-2 composite and also to the Al5456 alloy plates. The welding zones were studied by scanning electron microscopy, X-ray diffractometry, micro-hardness and shear tests. The weld interface layer became thinner from 23 to 5 μm, as the laser pulse distance was increased from 0.2 to 0.5 mm. Reinforcing of the Al alloy modified the phases at interface layer from Al-Fe intermetallic compounds (IMCs) in the DSS/Al alloy weld, to Al-Ni-Fe IMCs in the DSS/Al composite one, since more nickel was injected in the weld pool by BNi-2 reinforcements. This led to a remarkable reduction in crack tendency of the welds and decreased the hardness of the interface layer from ~950 HV to ~600 HV. Shear strengths of the DSS/Al composite welds were significantly increased by ~150%, from 46 to 114 MPa, in comparison to the DSS/Al alloy ones.展开更多
文摘Green and low carbon promote the application and development of light-weight materials in body-in-white. Large-scale die-casting Al alloy (DCAA) and high-strength thermo-formed steel sheet (TFSS) have put forward higher requirements for the application of joining technology of high-strength steel/Al dissimilar materials. Taking the new die-casting Al alloy body as an example, this paper systematically studies the progress of the latest joining methods of steel/Al dissimilar material with combination of two-layer plate and three-layer plate. By analyzing the joining technologies such as FSPR, RES, FDS and SPR, the technology and process characteristics of steel/Al dissimilar material joining are studied, and the joining technical feasibility and realization means of different material combination of the body are analyzed. The conditions of material combination, material thickness, material strength, flange height, preformed holes and joint spacing for achieving high-quality joining are given. The FSPR joining technology is developed and tested in order to meet with the joining of parts with DCAA and TFSS, especially for the joining of three-layer plates with them. It finds the method and technical basis for the realization of high quality joining of dissimilar materials, provides the early conditions for the application of large DCAA and TFSS parts in body-in-white, and meets the design requirements of new energy body. .
基金Project(2012AA040210)supported by the National High-Tech Research and Development Program of ChinaProject(510-C10293)supported by the Central Finance Special Fund to Support the Local University,ChinaProject(2010A090200048)supported by the Key Project of Industry,Education,Research of Guangdong Province and Ministry of Education,China
文摘The crack-free Ni60 A coating was fabricated on 45 steel substrate by laser cladding and the microstructure including solidification characteristics, phases constitution and phase distribution was systematically investigated. The high temperature friction and wear behavior of the cladding coating and substrate sliding against GCr15 ball under different loads was systematically evaluated. It was found that the coating has homogenous and fine microstructure consisting of γ（Ni） solid solution, a considerable amount of network Ni-Ni3 B eutectics, m^23C6 with the floret-shape structure and Cr B with the dark spot-shape structure uniformly distributing in interdendritic eutectics. The microhardness of the coating is about 2.6 times as much as that of the substrate. The coating produces higher friction values than the substrate under the same load condition, but the friction process on the coating keeps relatively stable. Wear rates of the coating are about 1/6.2 of that of the substrate under the higher load（300 g）. Wear mechanism of the substrate includes adhesion wear, abrasive wear, severe plastic deformation and oxidation wear, while that of the coating is merely a combination of mild abrasive wear and moderate oxidation wear.
基金financially supported by the National Natural Science Foundation of China (Nos. 52071300 and 51904278)the Special Funding Projects for Local Science and Technology Development guided by the Central Committee (No. YDZX20191400004587)+1 种基金the Key Research and Development Project of Zhejiang Province, China (No.2020C01131)the Innovation projects of colleges and universities in Shanxi Province, China (No. 2019L0577)。
文摘Hot compression tests were performed to investigate the hot deformation behavior of Fe–27.34Mn–8.63Al–1.03C lightweight steel and optimize the hot workability parameters. The temperature range was 900–1150℃ and the strain rate range was 0.01–5 s^(-1)on a Gleeble-3800 thermal simulator machine. The results showed that the flow stress increased with decreasing deformation temperature and increasing strain rate. According to the constitutive equation, the activation energy of hot deformation was 422.88 kJ·mol^(-1). The relationship between the critical stress and peak stress of the tested steel was established, and a dynamic recrystallization kinetic model was thus obtained. Based on this model, the effects of strain rate and deformation temperature on the volume fraction of dynamically recrystallized grains were explored. The microstructural examination and processing map results revealed that the tested steel exhibited a good hot workability at deformation temperatures of 1010–1100℃ and strain rate of 0.01 s^(-1).
基金Project(BK2005128) supported by the Natural Science Foundation of Jiangsu Province, China
文摘A binary Fe-Al alloyed layer was synthesized on 45 steel by means of double glow plasma surface alloying technique. The corrosion-resisting layer prepared is composed of a sedimentary layer and a diffusion layer, with a total thickness of about 180 μm. The aluminum content of the alloyed layer shows gradual change from surface to the inside of substrate. The ideal profile is beneficial to the metallurgical bonding of the surface alloying layer with substrate materials. The microstructure of both layers consists of the Fe-Al intermetallic compound, which is FeAl with B2 structure in the sedimentary layer and Fe3Al with incompletely ordered DO3 structure in the diffusion layer. The protective film exhibits high micro-hardness. In comparison with the substrate of 45 steel, the corrosion resistance of the aluminized sample is much higher in 2.0% Na2S and 0.05 mol/L Na2SO4 + 0.5 mol/L NaCl mixed solutions.
文摘Effects of laser pulse distance and reinforcing of 5456 aluminum alloy were investigated on laser weldability of Al alloy to duplex stainless steel (DSS) plates. The aluminum alloy plate was reinforced by nickel-base BNi-2 brazing powder via friction stir processing. The DSS plates were laser welded to the Al5456/BNi-2 composite and also to the Al5456 alloy plates. The welding zones were studied by scanning electron microscopy, X-ray diffractometry, micro-hardness and shear tests. The weld interface layer became thinner from 23 to 5 μm, as the laser pulse distance was increased from 0.2 to 0.5 mm. Reinforcing of the Al alloy modified the phases at interface layer from Al-Fe intermetallic compounds (IMCs) in the DSS/Al alloy weld, to Al-Ni-Fe IMCs in the DSS/Al composite one, since more nickel was injected in the weld pool by BNi-2 reinforcements. This led to a remarkable reduction in crack tendency of the welds and decreased the hardness of the interface layer from ~950 HV to ~600 HV. Shear strengths of the DSS/Al composite welds were significantly increased by ~150%, from 46 to 114 MPa, in comparison to the DSS/Al alloy ones.
