For contact dominated numerical control(NC) bending process of tube, the effect of friction on bending deformation behaviors should be focused on to achieve precision bending forming. A three dimensional(3D) elastic-p...For contact dominated numerical control(NC) bending process of tube, the effect of friction on bending deformation behaviors should be focused on to achieve precision bending forming. A three dimensional(3D) elastic-plastic finite element(FE) model of NC bending process was established under ABAQUS/Explicit platform, and its reliability was validated by the experiment. Then, numerical study on bending deformation behaviors under different frictions between tube and various dies was explored from multiple aspects such as wrinkling, wall thickness change and cross section deformation. The results show that the large friction of wiper die-tube reduces the wrinkling wave ratio η and cross section deformation degree ΔD and increases the wall thinning degree Δt. The large friction of mandrel-tube causes large η, Δt and ΔD, and the onset of wrinkling near clamp die. The large friction of pressure die-tube reduces Δt and ΔD, and the friction on this interface has little effect on η. The large friction of bending die-tube reduces η and ΔD, and the friction on this interface has little effect on Δt. The reasonable friction coefficients on wiper die-tube, mandrel-tube, pressure die-tube and bending die-tube of 21-6-9(0Cr21Ni6Mn9N) stainless steel tube in NC bending are 0.05-0.15, 0.05-0.15, 0.25-0.35 and 0.25-0.35, respectively. The results can provide a guideline for applying the friction conditions to establish the robust bending environment for stable and precise bending deformation of tube bending.展开更多
The technology of black coloring for stainless steel by electrochemical method was studied. The optimum bath compositions and operating conditions were obtained as follows: 4050g/L K2Cr2O7 , 1520g/L MnSO4, 1520g/L （...The technology of black coloring for stainless steel by electrochemical method was studied. The optimum bath compositions and operating conditions were obtained as follows: 4050g/L K2Cr2O7 , 1520g/L MnSO4, 1520g/L （NH4）2SO4, 2040g/L H3BO3, 2030 g/L additive A, 2 g/L （NH4）6Mo7O 24 ; time 920 min; temperature 1530℃; potential 3V and current density 12mA/cm 2 . The effects of the compositions of the bath on the quality of black colored film were discussed. The influences of passivation process on the black coloring velocity and performances of black colored film layer were investigated. The results show that the passivation process can improve the corrosion resistance and the stability to bear color-change; （NH4）2SO4 can control the black coloring velocity and prolong black coloring bath life remarkably; and additive A can improve the evenness and compactness of black colored film layer. The results of scanning electron microscopy and energy dispersive spectra show that the microstructure is of cylindrical lump, the filling process can decrease the crackles, and the main elements of black colored film are Fe, Cr, Mn and Ni.展开更多
Multi-layer laser cladding manufacturing is a newly developed rapid manufacturing technology. It is a powerful tool for direct fabrication of three-dimensional fully dense metal components and part repairing. In this ...Multi-layer laser cladding manufacturing is a newly developed rapid manufacturing technology. It is a powerful tool for direct fabrication of three-dimensional fully dense metal components and part repairing. In this paper, the microstructure evolution and properties of 316L stainless steel deposited with this technology was investigated, compact components with properties similar to the as-cast and wrought annealed material was obtained. Cracking was eliminated by introducing of supersonic vibration and application of parameter adjustment technologies.展开更多
Two thermo-mechanical controlled processes （TMCP） including controlled rolling and accelerated cooling are proposed for the production of heavy gauge SUS 304 L austenitic stainless steel plates with different streng...Two thermo-mechanical controlled processes （TMCP） including controlled rolling and accelerated cooling are proposed for the production of heavy gauge SUS 304 L austenitic stainless steel plates with different strengths and other characteristics. Based on the recrystallization mechanism and carbide precipitation behavior of SUS 304 L austenitic stainless steel ,TMCP provides a powerful means to control the microstructure and precipitation of the hot rolled steel plate by the controlled rolling and accelerated cooling process. The dislocation density and grain size are the main factors in determining the strength of the stainless steel plates. Therefore ,it is necessary to strictly control the hot rolling parameters, including parameters such as the finish hot rolling temperature in the recrystallization temperature region and the total reduction in the non-recrystallization region. Furthermore, in order to avoid carbide precipitation and guarantee the intergranular corrosion resistance of TMCP SUS 304 L austenitic stainless steel, a critical cooling rate after rolling is determined.展开更多
To avoid intergranular corrosion and obtain microstructural homogenization, the conventional SUS304 austenitic stainless steel needs to be solution annealed after hot rolling. This study investigates the thermal-mecha...To avoid intergranular corrosion and obtain microstructural homogenization, the conventional SUS304 austenitic stainless steel needs to be solution annealed after hot rolling. This study investigates the thermal-mechanical controlled process （TMCP） of SUS304 steel, especially the controlled rolling and online accelerated cooling procedures. The objective of this research is to reduce or even prevent carbide precipitation based on the description of the time- temperature-precipitation （TTP） curve. The dynamic and post-dynamic recrystallization behaviors of this steel ensured the homogenization of grains in this process due to, which was studied by the hot compression tests. The microstructure and the properties of the TMCP-produced SUS304 steel strip were compared with the conventional method of solution annealing. Based on the above results, the newly developed TMCP-produced SUS304 hot-rolled austenitic stainless steel strip has been successfully produced and it can be directly utilized in the cold rolling process without solution annealing.展开更多
This paper discusses the coloration process on the stainless steel and the properties of the film. The compositions, morphology and structure of colored films on stainless steel are studied by using SEM,AES,AFM,STM. ...This paper discusses the coloration process on the stainless steel and the properties of the film. The compositions, morphology and structure of colored films on stainless steel are studied by using SEM,AES,AFM,STM. The diffusion controlled mechanisms of films and calculation formula of surface electropotential difference are discussed.展开更多
Experimental investigation and thermodynamic calculation were carried out to study the effect of slag on alloying elements during electroslag remelting with developing a thermodynamic model to control titanium and alu...Experimental investigation and thermodynamic calculation were carried out to study the effect of slag on alloying elements during electroslag remelting with developing a thermodynamic model to control titanium and aluminum in in got.The thermodynamic model based on ion and molecule coexistence theory and conservation law of element atoms was established to analyze the change in aluminum and titanium along the height of ingot.The results show that low CaO slag is suitable for electroslag remelting of metal containing high titanium-to-aluminum ratio.As electroslag remelting process consists of slag temperature-rising and temperature-stable periods,TiO2 should be added into water-cooled copper mold during temperature-rising period in order to keep the thermodynamic equilibrium between titanium and aluminum,and the amount of TiO2 is the difference value calculated by the reaction between titanium and alumina at 1477 and 1677℃.展开更多
The strip shape in the stainless steel process has made an issue of the strip quality.The objective of the shape control is to minimize the shape deviation and to maintain symmetrical shape patterns in the lateral dir...The strip shape in the stainless steel process has made an issue of the strip quality.The objective of the shape control is to minimize the shape deviation and to maintain symmetrical shape patterns in the lateral direction.The method of the shape recognition employs the least square method.The shape deviation is controlled by the fuzzy shape controller（FSC）.The experiments have been performed online for various stainless materials,thicknesses,and strip widths.The test results show very efficient performances in respect of stable target tracking and symmetrical and minimal fluctuation of the strip shape.展开更多
To control the reverse-transformation austenite structure through manipulation of the micro/nanometer grain structure, the influences of cold deformation and annealing parameters on the microstructure evolution and me...To control the reverse-transformation austenite structure through manipulation of the micro/nanometer grain structure, the influences of cold deformation and annealing parameters on the microstructure evolution and mechanical properties of 316L austenitic stainless steel were investigated. The samples were first cold-rolled, and then samples deformed to different extents were annealed at different temperatures. The microstructure evolutions were analyzed by optical microscopy, scanning electron microscopy (SEM), magnetic measurements, and X-ray diffraction (XRD); the mechanical properties are also determined by tensile tests. The results showed that the fraction of stain-induced martensite was approximately 72% in the 90% cold-rolled steel. The micro/nanometric microstructure was obtained after reversion annealing at 820-870A degrees C for 60 s. Nearly 100% reversed austenite was obtained in samples annealed at 850A degrees C, where grains with a diameter ae<currency> 500 nm accounted for 30% and those with a diameter > 0.5 mu m accounted for 70%. The micro/nanometer-grain steel exhibited not only a high strength level (approximately 959 MPa) but also a desirable elongation of approximately 45%.展开更多
Based on the characteristics of ferritic SUS430 heating and deformation,and combined with the features of the 1780 mm hot-rolling mill,a roughing model was introduced in two aspects:optimizing the rough rolling passes...Based on the characteristics of ferritic SUS430 heating and deformation,and combined with the features of the 1780 mm hot-rolling mill,a roughing model was introduced in two aspects:optimizing the rough rolling passes and improving the width control precision.Through reducing the rough rolling passes,the rough rolling time can be shortened,the precision rolling startup temperature can be raised and the yield of the hot-rolled products can be increased.Moreover,on the premise that the slab width fluctuation was great,the precision of the width control can be improved through optimizing the parameters of the hot-rolling width control model.The result shows that the optimization and perfection of the original rolling process of the stainless steel 430 series further improved its capacity and product quality.展开更多
基金Project(51164030)supported by the National Natural Science Foundation of China
文摘For contact dominated numerical control(NC) bending process of tube, the effect of friction on bending deformation behaviors should be focused on to achieve precision bending forming. A three dimensional(3D) elastic-plastic finite element(FE) model of NC bending process was established under ABAQUS/Explicit platform, and its reliability was validated by the experiment. Then, numerical study on bending deformation behaviors under different frictions between tube and various dies was explored from multiple aspects such as wrinkling, wall thickness change and cross section deformation. The results show that the large friction of wiper die-tube reduces the wrinkling wave ratio η and cross section deformation degree ΔD and increases the wall thinning degree Δt. The large friction of mandrel-tube causes large η, Δt and ΔD, and the onset of wrinkling near clamp die. The large friction of pressure die-tube reduces Δt and ΔD, and the friction on this interface has little effect on η. The large friction of bending die-tube reduces η and ΔD, and the friction on this interface has little effect on Δt. The reasonable friction coefficients on wiper die-tube, mandrel-tube, pressure die-tube and bending die-tube of 21-6-9(0Cr21Ni6Mn9N) stainless steel tube in NC bending are 0.05-0.15, 0.05-0.15, 0.25-0.35 and 0.25-0.35, respectively. The results can provide a guideline for applying the friction conditions to establish the robust bending environment for stable and precise bending deformation of tube bending.
基金Project(04JJ40036) supported by the Natural Science Foundation of Hunan Province
文摘The technology of black coloring for stainless steel by electrochemical method was studied. The optimum bath compositions and operating conditions were obtained as follows: 4050g/L K2Cr2O7 , 1520g/L MnSO4, 1520g/L （NH4）2SO4, 2040g/L H3BO3, 2030 g/L additive A, 2 g/L （NH4）6Mo7O 24 ; time 920 min; temperature 1530℃; potential 3V and current density 12mA/cm 2 . The effects of the compositions of the bath on the quality of black colored film were discussed. The influences of passivation process on the black coloring velocity and performances of black colored film layer were investigated. The results show that the passivation process can improve the corrosion resistance and the stability to bear color-change; （NH4）2SO4 can control the black coloring velocity and prolong black coloring bath life remarkably; and additive A can improve the evenness and compactness of black colored film layer. The results of scanning electron microscopy and energy dispersive spectra show that the microstructure is of cylindrical lump, the filling process can decrease the crackles, and the main elements of black colored film are Fe, Cr, Mn and Ni.
基金supported by the National Natural Science Foundation of China under the Grant No.50375096
文摘Multi-layer laser cladding manufacturing is a newly developed rapid manufacturing technology. It is a powerful tool for direct fabrication of three-dimensional fully dense metal components and part repairing. In this paper, the microstructure evolution and properties of 316L stainless steel deposited with this technology was investigated, compact components with properties similar to the as-cast and wrought annealed material was obtained. Cracking was eliminated by introducing of supersonic vibration and application of parameter adjustment technologies.
文摘Two thermo-mechanical controlled processes （TMCP） including controlled rolling and accelerated cooling are proposed for the production of heavy gauge SUS 304 L austenitic stainless steel plates with different strengths and other characteristics. Based on the recrystallization mechanism and carbide precipitation behavior of SUS 304 L austenitic stainless steel ,TMCP provides a powerful means to control the microstructure and precipitation of the hot rolled steel plate by the controlled rolling and accelerated cooling process. The dislocation density and grain size are the main factors in determining the strength of the stainless steel plates. Therefore ,it is necessary to strictly control the hot rolling parameters, including parameters such as the finish hot rolling temperature in the recrystallization temperature region and the total reduction in the non-recrystallization region. Furthermore, in order to avoid carbide precipitation and guarantee the intergranular corrosion resistance of TMCP SUS 304 L austenitic stainless steel, a critical cooling rate after rolling is determined.
文摘To avoid intergranular corrosion and obtain microstructural homogenization, the conventional SUS304 austenitic stainless steel needs to be solution annealed after hot rolling. This study investigates the thermal-mechanical controlled process （TMCP） of SUS304 steel, especially the controlled rolling and online accelerated cooling procedures. The objective of this research is to reduce or even prevent carbide precipitation based on the description of the time- temperature-precipitation （TTP） curve. The dynamic and post-dynamic recrystallization behaviors of this steel ensured the homogenization of grains in this process due to, which was studied by the hot compression tests. The microstructure and the properties of the TMCP-produced SUS304 steel strip were compared with the conventional method of solution annealing. Based on the above results, the newly developed TMCP-produced SUS304 hot-rolled austenitic stainless steel strip has been successfully produced and it can be directly utilized in the cold rolling process without solution annealing.
文摘This paper discusses the coloration process on the stainless steel and the properties of the film. The compositions, morphology and structure of colored films on stainless steel are studied by using SEM,AES,AFM,STM. The diffusion controlled mechanisms of films and calculation formula of surface electropotential difference are discussed.
基金the National Natural Science Foundation of China(Grant Nos.51674070,U1560203 and 51674172)Natural Science Foundation of Jiangsu Province(Grant Nos.BK20150334 and 20150336)the Open Foundation of The State Key Laboratory of Refractories and Metallurgy(Grant No.G201607).
文摘Experimental investigation and thermodynamic calculation were carried out to study the effect of slag on alloying elements during electroslag remelting with developing a thermodynamic model to control titanium and aluminum in in got.The thermodynamic model based on ion and molecule coexistence theory and conservation law of element atoms was established to analyze the change in aluminum and titanium along the height of ingot.The results show that low CaO slag is suitable for electroslag remelting of metal containing high titanium-to-aluminum ratio.As electroslag remelting process consists of slag temperature-rising and temperature-stable periods,TiO2 should be added into water-cooled copper mold during temperature-rising period in order to keep the thermodynamic equilibrium between titanium and aluminum,and the amount of TiO2 is the difference value calculated by the reaction between titanium and alumina at 1477 and 1677℃.
文摘The strip shape in the stainless steel process has made an issue of the strip quality.The objective of the shape control is to minimize the shape deviation and to maintain symmetrical shape patterns in the lateral direction.The method of the shape recognition employs the least square method.The shape deviation is controlled by the fuzzy shape controller（FSC）.The experiments have been performed online for various stainless materials,thicknesses,and strip widths.The test results show very efficient performances in respect of stable target tracking and symmetrical and minimal fluctuation of the strip shape.
基金supported by the National Natural Science Foundation of China(Grant No.51474031)
文摘To control the reverse-transformation austenite structure through manipulation of the micro/nanometer grain structure, the influences of cold deformation and annealing parameters on the microstructure evolution and mechanical properties of 316L austenitic stainless steel were investigated. The samples were first cold-rolled, and then samples deformed to different extents were annealed at different temperatures. The microstructure evolutions were analyzed by optical microscopy, scanning electron microscopy (SEM), magnetic measurements, and X-ray diffraction (XRD); the mechanical properties are also determined by tensile tests. The results showed that the fraction of stain-induced martensite was approximately 72% in the 90% cold-rolled steel. The micro/nanometric microstructure was obtained after reversion annealing at 820-870A degrees C for 60 s. Nearly 100% reversed austenite was obtained in samples annealed at 850A degrees C, where grains with a diameter ae<currency> 500 nm accounted for 30% and those with a diameter > 0.5 mu m accounted for 70%. The micro/nanometer-grain steel exhibited not only a high strength level (approximately 959 MPa) but also a desirable elongation of approximately 45%.
文摘Based on the characteristics of ferritic SUS430 heating and deformation,and combined with the features of the 1780 mm hot-rolling mill,a roughing model was introduced in two aspects:optimizing the rough rolling passes and improving the width control precision.Through reducing the rough rolling passes,the rough rolling time can be shortened,the precision rolling startup temperature can be raised and the yield of the hot-rolled products can be increased.Moreover,on the premise that the slab width fluctuation was great,the precision of the width control can be improved through optimizing the parameters of the hot-rolling width control model.The result shows that the optimization and perfection of the original rolling process of the stainless steel 430 series further improved its capacity and product quality.
