In this study,the scale and internal oxidation of hot-rolled ultra-high strength steel sheets were characterized.It was found that both the formation of the scale and the internal oxidation of Si and Mn depended on th...In this study,the scale and internal oxidation of hot-rolled ultra-high strength steel sheets were characterized.It was found that both the formation of the scale and the internal oxidation of Si and Mn depended on the coiling temperature and position of the steel sample on the strip coil.At a relatively high coiling temperature,a large amount of internal oxidation was observed on the samples cut from the middle of the coil.The depth of the internal oxidation zone exceeded 10 μm and a thin iron layer covering the scale was observed in some cases.Pickling and cold-rolling experiments were conducted on selected samples.Scale pickling was found to be greatly delayed by the formation of an iron layer,which frequently resulted in under-pickled defects.In addition,pickling of the entire internal oxidation zone was difficult,except at the grain boundaries,where the degree of internal Si and Mn oxidation was enriched.The surface of the cold-rolled steel sheet was ruined by the remaining oxidation zone in the subsurface of the pickled steel.The internal oxidation of hot-rolled ultra-high strength steel must be precisely controlled to improve the subsequent surface quality of cold-rolled steel.展开更多
The textures variation of 3104 aluminum alloy sheets during hot rolling, cold rolling, transverse cold rolling and cross shear rolling were investigated by means of X ray ODF analysis. The results show that the main t...The textures variation of 3104 aluminum alloy sheets during hot rolling, cold rolling, transverse cold rolling and cross shear rolling were investigated by means of X ray ODF analysis. The results show that the main texture component {100}<011> becomes stronger with the increase of hot rolling reduction. The cold rolling textures are composed of typical "copper type" texture components C {112}<111>, S {123}<634>, R/S {124}<211>, B {110}<112> and G {110}<001>, the orientation intensities increase with increasing cold rolling reduction. Compared to the conventional cold rolling with the same amount reduction, the transverse rolling reduces the orientation intensities of each cold rolling textures components, and strengthens the {001}<110> and {110}<uvw> texture components. During cross shear rolling process, notable difference of intensity of cold rolling textures components were observed from the slow roller side to the fast roller.展开更多
The oxidation behaviour of 10%, 30%, and 50% cold rolled and unprocessed 9Cr 1Mo ferritic steels in air have been studied under isothermal conditions at a temperature of 900°C in a cyclic manner. Oxidation kineti...The oxidation behaviour of 10%, 30%, and 50% cold rolled and unprocessed 9Cr 1Mo ferritic steels in air have been studied under isothermal conditions at a temperature of 900°C in a cyclic manner. Oxidation kinetics was established for all samples on which experiment was conducted in air at 900°C under cyclic conditions for 50 cycles by thermogravimetric technique. Each cycle consisted of 1 hour heating at 900°C followed by 20 min of cooling in air. 10% cold rolled sample followed parabolic rate of oxidation while 30% cold rolled sample showed accelerated rate of weight gain. X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray (SEM/EDAX) techniques were used to characterise the oxidized sample and their scales. 10% cold rolled steel was found to be more corrosion resistance than other in air oxidation for 50 cycles.展开更多
The nitriding behavior of cold rolled Fe93Ni4Ti3 specimens was compared with that of hot rolled specimens of the same materials. Radio frequency (rf) nitriding was performed for 10 minutes in a 10-2 mbar nitrogen atmo...The nitriding behavior of cold rolled Fe93Ni4Ti3 specimens was compared with that of hot rolled specimens of the same materials. Radio frequency (rf) nitriding was performed for 10 minutes in a 10-2 mbar nitrogen atmosphere. The continuous plasma power was varied from 300-550 W in steps 50 W or less. Results of optical microscopy (OM), x-ray diffraction (XRD) and microhardness measurements (Hv) are presented and discussed with regard to the influence of kind rolling on the nitriding behavior, particularly nitride formation and nitride layer growth on mechanical properties. The results show a remarkable increase of nitrogen diffusivity and microhardness of cold rolled nitride samples. These best results may be attributed to enhancement of the defect and/or a compressive stress.展开更多
A new processing method for producing hot dip galvanized steel is designed and tested, in which pickling is skipped. Hot-rolled low carbon steel sheets are roiled with oxide scale in an experimental mill at room tempe...A new processing method for producing hot dip galvanized steel is designed and tested, in which pickling is skipped. Hot-rolled low carbon steel sheets are roiled with oxide scale in an experimental mill at room temperature, prior to annealing under a 20% hydrogen reducing atmosphere and galvanizing on a hot-dip galvanizing simulator. Micro-cracks formed in the oxide scale during cold rolling roughen the steel surface and enlarge the specific surface. Through-thickness cracks provide transport channels for hydrogen, and hence the reduction of oxide scale is en- hanced. When the sheet is dipped in the zinc bath, cracks are submerged by liquated zinc and the defects are not dis- tinct after hot-dip galvanizing. The overlay coating occludes with rough surface of the sheet, whereby a superior coat- ing adherence is realized.展开更多
Taking advantage of the progress of roll-bonding technology, the integrity of the material technology, and the development of the production and examination facilities of all the main carbon steels, stainless steels a...Taking advantage of the progress of roll-bonding technology, the integrity of the material technology, and the development of the production and examination facilities of all the main carbon steels, stainless steels and specialty alloys in Baosteel, the cladded flat new products, which combined both properties of base material and clad material ,have been developed and produced in large quantities. The product categories includes heavy plates with high alloy content and homogeneous distribution in thickness and carbon steel plates cladded with all kinds of stainless steels ,nickel alloys ,and titanium alloys. The double-sided and single-sided cladding hot roiled strips and cold rolled sheets were also commercially produced. Due to the combined properties of both the cladding material and backing material, all products show obvious improvement in properties when compared with solid material. The comparability with the existing production process and equipment laid a very solid foundation for high productivity.展开更多
The texture evolution of ferritic hot rolled Ti-IF steel during cold rolling was investigated in which the reduction was from 15% to 85 %. It was found that α fibre texture was monotonously intensified with the incre...The texture evolution of ferritic hot rolled Ti-IF steel during cold rolling was investigated in which the reduction was from 15% to 85 %. It was found that α fibre texture was monotonously intensified with the increase in the cold rolling reduction, while y fibre texture changed in a different way. When the cold rolling reduction was in the range of 15 % -- 35 % or 45 % -- 75 %, γ fibre texture was strengthened ; however, when the cold rolling reduction was 35 %- 45 % or 75 %- 85%, the intensity of 7 fibre was reduced. The 7 fibre displayed a maximum intensity for the reduction of 75%, and the highest average plastic strain ratio was simultaneously obtained owing to the favorable recrystallization texture.展开更多
文摘In this study,the scale and internal oxidation of hot-rolled ultra-high strength steel sheets were characterized.It was found that both the formation of the scale and the internal oxidation of Si and Mn depended on the coiling temperature and position of the steel sample on the strip coil.At a relatively high coiling temperature,a large amount of internal oxidation was observed on the samples cut from the middle of the coil.The depth of the internal oxidation zone exceeded 10 μm and a thin iron layer covering the scale was observed in some cases.Pickling and cold-rolling experiments were conducted on selected samples.Scale pickling was found to be greatly delayed by the formation of an iron layer,which frequently resulted in under-pickled defects.In addition,pickling of the entire internal oxidation zone was difficult,except at the grain boundaries,where the degree of internal Si and Mn oxidation was enriched.The surface of the cold-rolled steel sheet was ruined by the remaining oxidation zone in the subsurface of the pickled steel.The internal oxidation of hot-rolled ultra-high strength steel must be precisely controlled to improve the subsequent surface quality of cold-rolled steel.
文摘The textures variation of 3104 aluminum alloy sheets during hot rolling, cold rolling, transverse cold rolling and cross shear rolling were investigated by means of X ray ODF analysis. The results show that the main texture component {100}<011> becomes stronger with the increase of hot rolling reduction. The cold rolling textures are composed of typical "copper type" texture components C {112}<111>, S {123}<634>, R/S {124}<211>, B {110}<112> and G {110}<001>, the orientation intensities increase with increasing cold rolling reduction. Compared to the conventional cold rolling with the same amount reduction, the transverse rolling reduces the orientation intensities of each cold rolling textures components, and strengthens the {001}<110> and {110}<uvw> texture components. During cross shear rolling process, notable difference of intensity of cold rolling textures components were observed from the slow roller side to the fast roller.
文摘The oxidation behaviour of 10%, 30%, and 50% cold rolled and unprocessed 9Cr 1Mo ferritic steels in air have been studied under isothermal conditions at a temperature of 900°C in a cyclic manner. Oxidation kinetics was established for all samples on which experiment was conducted in air at 900°C under cyclic conditions for 50 cycles by thermogravimetric technique. Each cycle consisted of 1 hour heating at 900°C followed by 20 min of cooling in air. 10% cold rolled sample followed parabolic rate of oxidation while 30% cold rolled sample showed accelerated rate of weight gain. X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray (SEM/EDAX) techniques were used to characterise the oxidized sample and their scales. 10% cold rolled steel was found to be more corrosion resistance than other in air oxidation for 50 cycles.
文摘The nitriding behavior of cold rolled Fe93Ni4Ti3 specimens was compared with that of hot rolled specimens of the same materials. Radio frequency (rf) nitriding was performed for 10 minutes in a 10-2 mbar nitrogen atmosphere. The continuous plasma power was varied from 300-550 W in steps 50 W or less. Results of optical microscopy (OM), x-ray diffraction (XRD) and microhardness measurements (Hv) are presented and discussed with regard to the influence of kind rolling on the nitriding behavior, particularly nitride formation and nitride layer growth on mechanical properties. The results show a remarkable increase of nitrogen diffusivity and microhardness of cold rolled nitride samples. These best results may be attributed to enhancement of the defect and/or a compressive stress.
基金Item Sponsored by National Science and Technology Pillar Program of China(2011BAE13B04)
文摘A new processing method for producing hot dip galvanized steel is designed and tested, in which pickling is skipped. Hot-rolled low carbon steel sheets are roiled with oxide scale in an experimental mill at room temperature, prior to annealing under a 20% hydrogen reducing atmosphere and galvanizing on a hot-dip galvanizing simulator. Micro-cracks formed in the oxide scale during cold rolling roughen the steel surface and enlarge the specific surface. Through-thickness cracks provide transport channels for hydrogen, and hence the reduction of oxide scale is en- hanced. When the sheet is dipped in the zinc bath, cracks are submerged by liquated zinc and the defects are not dis- tinct after hot-dip galvanizing. The overlay coating occludes with rough surface of the sheet, whereby a superior coat- ing adherence is realized.
文摘Taking advantage of the progress of roll-bonding technology, the integrity of the material technology, and the development of the production and examination facilities of all the main carbon steels, stainless steels and specialty alloys in Baosteel, the cladded flat new products, which combined both properties of base material and clad material ,have been developed and produced in large quantities. The product categories includes heavy plates with high alloy content and homogeneous distribution in thickness and carbon steel plates cladded with all kinds of stainless steels ,nickel alloys ,and titanium alloys. The double-sided and single-sided cladding hot roiled strips and cold rolled sheets were also commercially produced. Due to the combined properties of both the cladding material and backing material, all products show obvious improvement in properties when compared with solid material. The comparability with the existing production process and equipment laid a very solid foundation for high productivity.
基金Item Sponsored by National Natural Science Foundation of China (50104004)
文摘The texture evolution of ferritic hot rolled Ti-IF steel during cold rolling was investigated in which the reduction was from 15% to 85 %. It was found that α fibre texture was monotonously intensified with the increase in the cold rolling reduction, while y fibre texture changed in a different way. When the cold rolling reduction was in the range of 15 % -- 35 % or 45 % -- 75 %, γ fibre texture was strengthened ; however, when the cold rolling reduction was 35 %- 45 % or 75 %- 85%, the intensity of 7 fibre was reduced. The 7 fibre displayed a maximum intensity for the reduction of 75%, and the highest average plastic strain ratio was simultaneously obtained owing to the favorable recrystallization texture.
