The modifying effect of rare earth (RE) oxide on inclusions in hardfacing metals of medium-high carbon steel was investigated by means of thermodynamics. The thermodynamic analysis for inclusion formation shows that ...The modifying effect of rare earth (RE) oxide on inclusions in hardfacing metals of medium-high carbon steel was investigated by means of thermodynamics. The thermodynamic analysis for inclusion formation shows that RE oxide can be reduced to RE element by carbon, then the RE element can react with oxygen and sulfur to form the RE oxide, RE sulfide and RE oxide-sulfide in hardfacing molten pool. The deoxidization and the desulphurization can be carried out and the liquid metal can be purified. In addition, RE oxide can also react with sulfur to form RE oxide-sulfide directly. Therefore, the harmful effect of sulfur can be decreased.展开更多
The evolution of oxide inclusions during isothermal heating of 18Cr–8Ni stainless steel with yttrium addition at temperatures of 1273 to 1573 K was investigated systematically.Homogeneous spherical Al–Y–Si(–Mn–Cr...The evolution of oxide inclusions during isothermal heating of 18Cr–8Ni stainless steel with yttrium addition at temperatures of 1273 to 1573 K was investigated systematically.Homogeneous spherical Al–Y–Si(–Mn–Cr)oxide inclusions were observed in as-cast steel.After heating,most of the homogeneous inclusions were transformed into heterogeneous inclusions with Y-rich and Al-rich parts,even though some homogeneous oxide particles were still observed at 1273 and 1573 K.With the increase in heating temperature,more large-sized inclusions were formed.The shape of the inclusions also changed from spherical to irregular.The maximum transformation temperature of inclusions was determined to be 1373 K.The evolution mechanism of inclusions during heating was proposed to be the combined effect of the(i)internal transformation of inclusions due to the crystallization of glassy oxide and(ii)interfacial reaction between inclusions and steel matrix.Meanwhile,the internal transformation of inclusions was considered to be the main factor at heating temperatures less than 1473 K.展开更多
In order to control the composition,morphology and size distribution of oxide inclusions in spring steel,the relationship between the content or activity of aluminum and calcium in molten steel and compositions of oxi...In order to control the composition,morphology and size distribution of oxide inclusions in spring steel,the relationship between the content or activity of aluminum and calcium in molten steel and compositions of oxide inclusion precipitated at different temperatures was determined based on thermodynamic equilibrium for spring steel 60Si2 MnA,and has been verified by practice.The size distribution of non-metallic inclusions electrolytically extracted from specimens of hot rolled spring steel was determined by image analyzer.The results show that there are a great deal of large inclusions in spring steel produced by the conventional process,and the quantity and the size of large inclusions in spring steel produced by new process are largely reduced.As a result,the fatigue properties of the spring steel produced by new process are highly improved,and the ratio ofσ-1/σbis raised from 0.451 to 0.468.展开更多
The key role of oxide inclusions on the microstructure and mechanical property of a high-strength low-alloy steel was investigated.The field emission scanning electron microscope equipped with energy-dispersive spectr...The key role of oxide inclusions on the microstructure and mechanical property of a high-strength low-alloy steel was investigated.The field emission scanning electron microscope equipped with energy-dispersive spectrometry was used to characterize MnS precipitates.Oxide inclusions play an important role in the shape control of MnS precipitates.More oxides fovored to decrease the size and the aspect ratio of MnS precipitates.With less oxide inclusions in the steel,approximately over 16.7%MnS precipitates were with aspect ratio a>5 and pure MnS precipitates accounted for 75.9%in number.However,with more oxide inclusions in the steel,only 7.4%MnS precipitates were with a>5 and pure MnS precipitates accounted for 60.1%in number.Refinement of MnS by oxide inclusions improved the strength and inhibited the anisotropy.More oxide inclusions in the steel increased the yield strength and tensile strength of the steel in both longitudinal and transverse directions,and lowered the anisotropy of the mechanical property.展开更多
The 42 kg industrial H13 castings were prepared by different super-gravity fields with multi-rotation speeds,and the distribution of oxide inclusions in the castings was studied.In addition,the inward movement Reynold...The 42 kg industrial H13 castings were prepared by different super-gravity fields with multi-rotation speeds,and the distribution of oxide inclusions in the castings was studied.In addition,the inward movement Reynolds number and inward movement time of oxide inclusions as well as the solidification time of molten steel at different positions in the castings were calculated to clarify the removal mechanism of oxide inclusions in super-gravity field.The results show that the large size(i.e.,greater than 10μm)oxide inclusions are mainly concentrated in the inner and outer parts of the super-gravity castings with constant rotation speed(500 r min^(-1))and five-stage rotation speeds(500,600,750,850,and 950 r min^(-1)),respectively,while there are no large oxide inclusions in the super-gravity castings with three-stage rotation speeds(500,600,and 750 r min^(-1)).Although an increase in the particle size of inclusion and the rotation speed in super-gravity field is conducive to the increase in the inward movement Reynolds number of oxide inclusions and reduction in the inward movement time of oxide inclusions,it will reduce the local solidification time of molten steel.In the range of the rotation speed studied,the super-gravity field with three-stage rotation speeds has the best effect on the removal of inclusions in H13 molten steel.展开更多
It is challenging to assess the mechanism responsible for the nucleation of inclusions in metals at high temperatures.The present work therefore systematically investigates the nucleation of cerium oxide inclusions ac...It is challenging to assess the mechanism responsible for the nucleation of inclusions in metals at high temperatures.The present work therefore systematically investigates the nucleation of cerium oxide inclusions according to classical nucleation theory and a two-step nucleation mechanism.The nucleation rates and nucleation radii of these inclusions are obtained,and the results demonstrate a considerable difference between theoretical and experimental values.On the basis of a two-step nucleation mechanism,(CeO_(2))_(n) and(Ce_(2)O_(3))_(n)(n=1-6)clusters were constructed and the thermodynamic properties of both these clusters and of cerium oxide nanoparticles were analyzed.In addition,the entropies and heat capacity changes of cerium oxides were determined using first principles calculations and are found to be consistent with literature data.The present data indicate that the cerium oxide inclusion nucleation pathway can be summarized as[Ce]+[O]→(CeO_(2))n/(Ce_(2)O_(3))_(n)→(Ce_(2)O_(3))_(n)→(Ce_(2)O_(3))_(2)→core(Ce_(2)O_(3)crystal)-shell((Ce_(2)O_(3))_(2) cluster)nanoparticles→(Ce_(2)O_(3))bulk.展开更多
In the present study, the market needs for the （HAZ） toughness are analyzed, and the mechanism of the development of steel plates with excellent heat affected zone decrease in the HAZ toughness during high-heat inpu...In the present study, the market needs for the （HAZ） toughness are analyzed, and the mechanism of the development of steel plates with excellent heat affected zone decrease in the HAZ toughness during high-heat input welding is discussed.The important countermeasure for improving the HAZ toughness is to employ the technology of oxide metallurgy ,namely,to make use of fine inclusion particles for improving the microstructure of HAZ. The progress and theories of oxide metallurgy technologies developed in the Nippon Steel Corporation （ NSC）, the JFE Steel Corporation and the Kobe Steel Group are illustrated. Steel plates developed by these three companies with excellent HAZ toughness are introduced.展开更多
Data from a thermodynamic database and the calculation software FactSage were used to investigate the phase diagrams of the MnO？CaO？SiO2？Al2O3 system in cutting-wire steel and the effects of oxide components on the...Data from a thermodynamic database and the calculation software FactSage were used to investigate the phase diagrams of the MnO？CaO？SiO2？Al2O3 system in cutting-wire steel and the effects of oxide components on the low-melting-point （LMP） zone in the cor-responding phase diagrams. Furthermore, the activities of oxide components in the quaternary system at an Al2O3 content of 25wt%were calculated. The contents of dissolved [Al] and [O] in liquid steel in equilibrium with LMP inclusions in the MnO-CaO-SiO2-Al2O3 system were optimized. The results show that the MnO-CaO-SiO2-Al2O3 system possesses the largest LMP zone （below 1400℃） at an Al2O3 content of 25wt%and that the CaO content should be simultaneously controlled in the range of 40wt%to 45wt%. The activities of the oxide components CaO, MnO, and SiO2 should be restricted in the ranges of 0 to 0.05, 0.01 to 0.6, and 0.001 to 0.8, respectively. To obtain LMP inclusions, the [Al] and [O] contents in cutting-wire steel must be controlled within the ranges of 0.5 ×10^-6 to 1.0 ×10^-5 and 3.0 ×10^-6 to 5.0 × 10^-5, respectively.展开更多
Nitrogen is an important gas-phase element in geological fluid,and normally hosted in mineralizing fluid,in which the content is very low.Nearly 100% mol pure nitrogen inclusion was discovered in copper-bearing quartz...Nitrogen is an important gas-phase element in geological fluid,and normally hosted in mineralizing fluid,in which the content is very low.Nearly 100% mol pure nitrogen inclusion was discovered in copper-bearing quartz vein from Xikuangshan copper deposit,Dongchuan,Yunnan Province in this research.It is between 3 and 5 μm,in shape of ellipse,occurring in group or independence without obvious orientation,and co-existed with primary gas-liquid inclusions.Inclusion analysis by using laser Raman spectroscopy shows its composition is dominated by nitrogen with minor H2O.High concentration of N2 may be the necessary and sufficient condition for forming this kind of inclusion.It is suggested that there are two genesis modes of pure N2 inclusion in the deposit,oxida-tion-devolativation of mantle matter and trap of metasomatic fluid in organic matter decomposition in Luoxue For-mation dolomite.In conclusion,pure N2 inclusion hardly presents in the ore-forming fluids,which providing a new evidence for the genesis of Xikuangshan type copper deposit.展开更多
The laboratory experiments,thermodynamic analysis,dynamic analysis,and industrial trials were carried out to investigate the influence of refining slag on the evolution and removal of oxide inclusions in 55SiCrA sprin...The laboratory experiments,thermodynamic analysis,dynamic analysis,and industrial trials were carried out to investigate the influence of refining slag on the evolution and removal of oxide inclusions in 55SiCrA spring steel.The reduction in basicity and Al_(2)O_(3) content in refining slag can reduce the[Al]s content in the molten steel,which is conducive to the control of the low melting point of inclusions.However,the refining slag with excessively low basicity transfers the oxygen element to molten steel and increases the Al_(2)O_(3) content in inclusions,which is harmful to the control of inclusions.According to the chemical compositions of inclusions and refining slag in laboratory experiments,their physical parameters were calculated.The maximum separation ratio and the moving time of inclusions to reach the maximum separation ratio(t_(max))of inclusions under different laboratory experimental conditions were studied.The maximum separation ratio of inclusions is positively correlated with the overall wettability(coshIMS)among the slag,steel,and inclusions.The maximum separation ratio of inclusions obtained by laboratory experiments is between 85%and 91%.The t_(max) decreases with the decline in basicity and Al_(2)O_(3) content of refining slag,but excessively low basicity will increase the t_(max).The basicity of refining slag in the range of 0.88–0.97 and the content of Al_(2)O_(3) less than 6%is not only conducive to reducing the content of Al_(2)O_(3) and the melting point of inclusions but also beneficial to removing the inclusions to the slag.The slag system shows good metallurgical results in industrial trials.展开更多
文摘The modifying effect of rare earth (RE) oxide on inclusions in hardfacing metals of medium-high carbon steel was investigated by means of thermodynamics. The thermodynamic analysis for inclusion formation shows that RE oxide can be reduced to RE element by carbon, then the RE element can react with oxygen and sulfur to form the RE oxide, RE sulfide and RE oxide-sulfide in hardfacing molten pool. The deoxidization and the desulphurization can be carried out and the liquid metal can be purified. In addition, RE oxide can also react with sulfur to form RE oxide-sulfide directly. Therefore, the harmful effect of sulfur can be decreased.
基金the National Natural Science Foundation of China(Nos.51574190 and51734003)the Fundamental Research Funds for the Central Universities of China(No.FRF-TP-18-009C1)the China Scholarship Council(No.201806460049)。
文摘The evolution of oxide inclusions during isothermal heating of 18Cr–8Ni stainless steel with yttrium addition at temperatures of 1273 to 1573 K was investigated systematically.Homogeneous spherical Al–Y–Si(–Mn–Cr)oxide inclusions were observed in as-cast steel.After heating,most of the homogeneous inclusions were transformed into heterogeneous inclusions with Y-rich and Al-rich parts,even though some homogeneous oxide particles were still observed at 1273 and 1573 K.With the increase in heating temperature,more large-sized inclusions were formed.The shape of the inclusions also changed from spherical to irregular.The maximum transformation temperature of inclusions was determined to be 1373 K.The evolution mechanism of inclusions during heating was proposed to be the combined effect of the(i)internal transformation of inclusions due to the crystallization of glassy oxide and(ii)interfacial reaction between inclusions and steel matrix.Meanwhile,the internal transformation of inclusions was considered to be the main factor at heating temperatures less than 1473 K.
基金Item Sponsored by National Natural Science Foundation of China(59874023)
文摘In order to control the composition,morphology and size distribution of oxide inclusions in spring steel,the relationship between the content or activity of aluminum and calcium in molten steel and compositions of oxide inclusion precipitated at different temperatures was determined based on thermodynamic equilibrium for spring steel 60Si2 MnA,and has been verified by practice.The size distribution of non-metallic inclusions electrolytically extracted from specimens of hot rolled spring steel was determined by image analyzer.The results show that there are a great deal of large inclusions in spring steel produced by the conventional process,and the quantity and the size of large inclusions in spring steel produced by new process are largely reduced.As a result,the fatigue properties of the spring steel produced by new process are highly improved,and the ratio ofσ-1/σbis raised from 0.451 to 0.468.
基金the National Natural Science Foundation of China(Grant Nos.52274398 and U22A20171)S&T Program of Hebei(Grant Nos.20311005D and 20591001D)the High Steel Center(HSC)at North China University of Technology and Yanshan University,China.
文摘The key role of oxide inclusions on the microstructure and mechanical property of a high-strength low-alloy steel was investigated.The field emission scanning electron microscope equipped with energy-dispersive spectrometry was used to characterize MnS precipitates.Oxide inclusions play an important role in the shape control of MnS precipitates.More oxides fovored to decrease the size and the aspect ratio of MnS precipitates.With less oxide inclusions in the steel,approximately over 16.7%MnS precipitates were with aspect ratio a>5 and pure MnS precipitates accounted for 75.9%in number.However,with more oxide inclusions in the steel,only 7.4%MnS precipitates were with a>5 and pure MnS precipitates accounted for 60.1%in number.Refinement of MnS by oxide inclusions improved the strength and inhibited the anisotropy.More oxide inclusions in the steel increased the yield strength and tensile strength of the steel in both longitudinal and transverse directions,and lowered the anisotropy of the mechanical property.
基金This work was financially supported by China Postdoctoral Fund(No.2021M700394)Key R&D Plan of Shandong Province in 2021(No.2021CXGC010209).The authors thank the Beijing Key Laboratory of Special Melting and Preparation of High-end Metal Materials for its support.The authors wish to thank the timely help given by Li-hui Han in University of Science and Technology Beijing.
文摘The 42 kg industrial H13 castings were prepared by different super-gravity fields with multi-rotation speeds,and the distribution of oxide inclusions in the castings was studied.In addition,the inward movement Reynolds number and inward movement time of oxide inclusions as well as the solidification time of molten steel at different positions in the castings were calculated to clarify the removal mechanism of oxide inclusions in super-gravity field.The results show that the large size(i.e.,greater than 10μm)oxide inclusions are mainly concentrated in the inner and outer parts of the super-gravity castings with constant rotation speed(500 r min^(-1))and five-stage rotation speeds(500,600,750,850,and 950 r min^(-1)),respectively,while there are no large oxide inclusions in the super-gravity castings with three-stage rotation speeds(500,600,and 750 r min^(-1)).Although an increase in the particle size of inclusion and the rotation speed in super-gravity field is conducive to the increase in the inward movement Reynolds number of oxide inclusions and reduction in the inward movement time of oxide inclusions,it will reduce the local solidification time of molten steel.In the range of the rotation speed studied,the super-gravity field with three-stage rotation speeds has the best effect on the removal of inclusions in H13 molten steel.
基金Project supported by the National Natural Science Foundation of China(52064011,52274331)Science and Technology Planning Project of Guizhou(Qian Ke He Ji Chu ZK[2021]258,Qian Ke He Chengguo[2022]089,Qian Ke He Chengguo[2021]086)。
文摘It is challenging to assess the mechanism responsible for the nucleation of inclusions in metals at high temperatures.The present work therefore systematically investigates the nucleation of cerium oxide inclusions according to classical nucleation theory and a two-step nucleation mechanism.The nucleation rates and nucleation radii of these inclusions are obtained,and the results demonstrate a considerable difference between theoretical and experimental values.On the basis of a two-step nucleation mechanism,(CeO_(2))_(n) and(Ce_(2)O_(3))_(n)(n=1-6)clusters were constructed and the thermodynamic properties of both these clusters and of cerium oxide nanoparticles were analyzed.In addition,the entropies and heat capacity changes of cerium oxides were determined using first principles calculations and are found to be consistent with literature data.The present data indicate that the cerium oxide inclusion nucleation pathway can be summarized as[Ce]+[O]→(CeO_(2))n/(Ce_(2)O_(3))_(n)→(Ce_(2)O_(3))_(n)→(Ce_(2)O_(3))_(2)→core(Ce_(2)O_(3)crystal)-shell((Ce_(2)O_(3))_(2) cluster)nanoparticles→(Ce_(2)O_(3))bulk.
文摘In the present study, the market needs for the （HAZ） toughness are analyzed, and the mechanism of the development of steel plates with excellent heat affected zone decrease in the HAZ toughness during high-heat input welding is discussed.The important countermeasure for improving the HAZ toughness is to employ the technology of oxide metallurgy ,namely,to make use of fine inclusion particles for improving the microstructure of HAZ. The progress and theories of oxide metallurgy technologies developed in the Nippon Steel Corporation （ NSC）, the JFE Steel Corporation and the Kobe Steel Group are illustrated. Steel plates developed by these three companies with excellent HAZ toughness are introduced.
文摘Data from a thermodynamic database and the calculation software FactSage were used to investigate the phase diagrams of the MnO？CaO？SiO2？Al2O3 system in cutting-wire steel and the effects of oxide components on the low-melting-point （LMP） zone in the cor-responding phase diagrams. Furthermore, the activities of oxide components in the quaternary system at an Al2O3 content of 25wt%were calculated. The contents of dissolved [Al] and [O] in liquid steel in equilibrium with LMP inclusions in the MnO-CaO-SiO2-Al2O3 system were optimized. The results show that the MnO-CaO-SiO2-Al2O3 system possesses the largest LMP zone （below 1400℃） at an Al2O3 content of 25wt%and that the CaO content should be simultaneously controlled in the range of 40wt%to 45wt%. The activities of the oxide components CaO, MnO, and SiO2 should be restricted in the ranges of 0 to 0.05, 0.01 to 0.6, and 0.001 to 0.8, respectively. To obtain LMP inclusions, the [Al] and [O] contents in cutting-wire steel must be controlled within the ranges of 0.5 ×10^-6 to 1.0 ×10^-5 and 3.0 ×10^-6 to 5.0 × 10^-5, respectively.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant Nos.KZCX2-YW-111-03 and KZCX2-YW-136-2)the National '973 Project'(No.2009CB421003)the Foundation of State Key Lab
文摘Nitrogen is an important gas-phase element in geological fluid,and normally hosted in mineralizing fluid,in which the content is very low.Nearly 100% mol pure nitrogen inclusion was discovered in copper-bearing quartz vein from Xikuangshan copper deposit,Dongchuan,Yunnan Province in this research.It is between 3 and 5 μm,in shape of ellipse,occurring in group or independence without obvious orientation,and co-existed with primary gas-liquid inclusions.Inclusion analysis by using laser Raman spectroscopy shows its composition is dominated by nitrogen with minor H2O.High concentration of N2 may be the necessary and sufficient condition for forming this kind of inclusion.It is suggested that there are two genesis modes of pure N2 inclusion in the deposit,oxida-tion-devolativation of mantle matter and trap of metasomatic fluid in organic matter decomposition in Luoxue For-mation dolomite.In conclusion,pure N2 inclusion hardly presents in the ore-forming fluids,which providing a new evidence for the genesis of Xikuangshan type copper deposit.
基金This work was financially supported by the State Key Laboratory of Advanced Metallurgy Foundation(No.41621005)the Subject of Xiangtan Branch,Hunan Valin Iron&Steel Co.,Ltd.,China(No.2018386).
文摘The laboratory experiments,thermodynamic analysis,dynamic analysis,and industrial trials were carried out to investigate the influence of refining slag on the evolution and removal of oxide inclusions in 55SiCrA spring steel.The reduction in basicity and Al_(2)O_(3) content in refining slag can reduce the[Al]s content in the molten steel,which is conducive to the control of the low melting point of inclusions.However,the refining slag with excessively low basicity transfers the oxygen element to molten steel and increases the Al_(2)O_(3) content in inclusions,which is harmful to the control of inclusions.According to the chemical compositions of inclusions and refining slag in laboratory experiments,their physical parameters were calculated.The maximum separation ratio and the moving time of inclusions to reach the maximum separation ratio(t_(max))of inclusions under different laboratory experimental conditions were studied.The maximum separation ratio of inclusions is positively correlated with the overall wettability(coshIMS)among the slag,steel,and inclusions.The maximum separation ratio of inclusions obtained by laboratory experiments is between 85%and 91%.The t_(max) decreases with the decline in basicity and Al_(2)O_(3) content of refining slag,but excessively low basicity will increase the t_(max).The basicity of refining slag in the range of 0.88–0.97 and the content of Al_(2)O_(3) less than 6%is not only conducive to reducing the content of Al_(2)O_(3) and the melting point of inclusions but also beneficial to removing the inclusions to the slag.The slag system shows good metallurgical results in industrial trials.
