A theoretical investigation of heat flow, solidification and solid shell resistance “Ic” has been undertaken by using a mathematical model and previous plant trials. The ultimate purpose is to develop operating cond...A theoretical investigation of heat flow, solidification and solid shell resistance “Ic” has been undertaken by using a mathematical model and previous plant trials. The ultimate purpose is to develop operating conditions and therefore to improve the surface quality for continuously cast steel slabs. A new simple criterion called mold thermomechanical rigidity “MTMR” has been proposed to evaluate and to improve these purposes. The parameters of MTMR and its non-dimensional number which use to control the surface defects are present in this investigation. Previous plant trails of slab surface defects formation have been investigated thermo-mechanically with this criterion. The predications show that this criterion is very sensitive of operating parameters and is a significant qualitative tool to evaluate the surface quality. From examination of the behavior of MTMR, the susceptibility and mechanism of surface defects formations with MTMR have been primarily discussed.展开更多
Baostrip has chosen a steel-grade weathering steel for industrial trial. By carefully designing the composition and manufacturing process,qualified weathering-steel products have been successfully produced on the Ning...Baostrip has chosen a steel-grade weathering steel for industrial trial. By carefully designing the composition and manufacturing process,qualified weathering-steel products have been successfully produced on the Ningbosteel-Baosteel strip casting industrialization demo project( NBS) production line. The industrialized practice of Baostrip shows the following: The surface microstructure of weathering-steel products is polygonal ferrite +pearlite,and that of the center is acicular ferrite. After single-stand on-line hot rolling at a 26% low pressure rate,the thickness tolerance ratio controlled within ± 25 μm reaches 99. 6%. The surface convexity and the wedge can be controlled to | C40 |< 50 μm and | W40 |< 30 μm,respectively. The mechanical properties of the strip are superior,exhibiting a yield strength range of( 430 ± 50) MPa,a tensile strength range of( 550 ± 50) MPa,and an elongation range of( 27 ± 5)%. The corrosion resistance is equivalent to that of current commercial atmospheric corrosion-resistant steels,with a relative corrosion rate of 43%. When used,the weathering steel produced by the strip-casting process meets the strict quality and usage requirements of container steel sheets.展开更多
Internal grinding is more difficult than surface grinding and cylindrical grinding. But littleresearch work in this field has been done. In this paper, based on a series of investigations, in-ternal grinding with vitr...Internal grinding is more difficult than surface grinding and cylindrical grinding. But littleresearch work in this field has been done. In this paper, based on a series of investigations, in-ternal grinding with vitrified bond CBN wheels was proposed. The method is considered mostsuitable for grinding ball-bearing parts in mass production as well as for CNC grinder. Thetheoretical analyses or internal grinding are also given, and a large number of textile machineparts-shell roller(the material is bearing steel GCr15) were grinded using Cr-corundumwheels and cubic boron nitride(CBN) wheels. Experiments indicated that grinding with CBNwheels had technical and economical advantages, and it might be used in a wider range.展开更多
A ceramic matrix coating for minimizing steel loss of stainless steel at high temperatures was prepared by handled air-spraying technique, and the influence of coating on surface quality of stainless steel was mainly ...A ceramic matrix coating for minimizing steel loss of stainless steel at high temperatures was prepared by handled air-spraying technique, and the influence of coating on surface quality of stainless steel was mainly investiga ted in laboratory. Experimental results showed that the protective coating reduced the oxidation of stainless steel by more than 91% and minimized high temperature scaling and also enhanced steel surface quality. The scales of coated specimen were removed completely and the scales of uncoated specimen were partly residual on the surface after cool ing process. Mn-rich and Fe-rich zones were found in the oxides. The Cr2 O3 found in scales came from the underlying stainless steel and formed a Cr rich layer along the spalled surface.展开更多
文摘A theoretical investigation of heat flow, solidification and solid shell resistance “Ic” has been undertaken by using a mathematical model and previous plant trials. The ultimate purpose is to develop operating conditions and therefore to improve the surface quality for continuously cast steel slabs. A new simple criterion called mold thermomechanical rigidity “MTMR” has been proposed to evaluate and to improve these purposes. The parameters of MTMR and its non-dimensional number which use to control the surface defects are present in this investigation. Previous plant trails of slab surface defects formation have been investigated thermo-mechanically with this criterion. The predications show that this criterion is very sensitive of operating parameters and is a significant qualitative tool to evaluate the surface quality. From examination of the behavior of MTMR, the susceptibility and mechanism of surface defects formations with MTMR have been primarily discussed.
基金funded by Shanghai Engineering Research Center of Strip Casting and Rolling(No.11DZ2282300)
文摘Baostrip has chosen a steel-grade weathering steel for industrial trial. By carefully designing the composition and manufacturing process,qualified weathering-steel products have been successfully produced on the Ningbosteel-Baosteel strip casting industrialization demo project( NBS) production line. The industrialized practice of Baostrip shows the following: The surface microstructure of weathering-steel products is polygonal ferrite +pearlite,and that of the center is acicular ferrite. After single-stand on-line hot rolling at a 26% low pressure rate,the thickness tolerance ratio controlled within ± 25 μm reaches 99. 6%. The surface convexity and the wedge can be controlled to | C40 |< 50 μm and | W40 |< 30 μm,respectively. The mechanical properties of the strip are superior,exhibiting a yield strength range of( 430 ± 50) MPa,a tensile strength range of( 550 ± 50) MPa,and an elongation range of( 27 ± 5)%. The corrosion resistance is equivalent to that of current commercial atmospheric corrosion-resistant steels,with a relative corrosion rate of 43%. When used,the weathering steel produced by the strip-casting process meets the strict quality and usage requirements of container steel sheets.
文摘Internal grinding is more difficult than surface grinding and cylindrical grinding. But littleresearch work in this field has been done. In this paper, based on a series of investigations, in-ternal grinding with vitrified bond CBN wheels was proposed. The method is considered mostsuitable for grinding ball-bearing parts in mass production as well as for CNC grinder. Thetheoretical analyses or internal grinding are also given, and a large number of textile machineparts-shell roller(the material is bearing steel GCr15) were grinded using Cr-corundumwheels and cubic boron nitride(CBN) wheels. Experiments indicated that grinding with CBNwheels had technical and economical advantages, and it might be used in a wider range.
基金Item Sponsored by National Natural Science Foundation of China(51202249)Key Projects in National Science and Technology Pillar Program in the Twelfth Five-year Plan of China(2012BAB08B04)
文摘A ceramic matrix coating for minimizing steel loss of stainless steel at high temperatures was prepared by handled air-spraying technique, and the influence of coating on surface quality of stainless steel was mainly investiga ted in laboratory. Experimental results showed that the protective coating reduced the oxidation of stainless steel by more than 91% and minimized high temperature scaling and also enhanced steel surface quality. The scales of coated specimen were removed completely and the scales of uncoated specimen were partly residual on the surface after cool ing process. Mn-rich and Fe-rich zones were found in the oxides. The Cr2 O3 found in scales came from the underlying stainless steel and formed a Cr rich layer along the spalled surface.
