Clean high carbon heavy rail steel was prepared by the process of vacuum induction furnace smelting,forging and rolling.Mechanisms of RE on the impact toughness and fracture toughness for clean high carbon steel were ...Clean high carbon heavy rail steel was prepared by the process of vacuum induction furnace smelting,forging and rolling.Mechanisms of RE on the impact toughness and fracture toughness for clean high carbon steel were investigated.In addition,the appropriate range of RE content for clean high carbon steel was determined.Both the austenite grain size and pearlite lamellar spacing decreased due to small amount of RE,consequently the impact toughness and fracture toughness were improved evidently.When the RE content exceeded a critical value,the pearlite lamellar spacing was increased,because RE was segregated on the austenite grain boundaries,damaged the orientation relationship of pearlite transformation,caused the disorder growth and morphology degenerating of pearlite.With the increasing of RE content,both the impact toughness and fracture toughness of clean high carbon steel were gradually increased at first and then decreased.It was found that when the RE content was between 0.0081% and 0.0088%,both the impact toughness and fracture toughness of clean high carbon heavy rail steel were the best.The maximum ballistic work was 21.2 J（20 ℃） and 12.2 J（-20 ℃）,respectively.The maximum plane-strain fracture toughness was 45.67 MPa·m1/2（20 ℃） and 37.04 MPa·m1/2（-20 ℃）,respectively.展开更多
The mechanisms of RE in clean BNbRE steel were studied by means of experimental measurement, microstructural observation and theoretical analysis. For BNbRE steel, the state and the content of RE were measured, and th...The mechanisms of RE in clean BNbRE steel were studied by means of experimental measurement, microstructural observation and theoretical analysis. For BNbRE steel, the state and the content of RE were measured, and the effects and the mechanisms of RE on sulfide inclusions, microstructure and properties of steel were determined. On the condition of increasing the cleanliness of steel, the mechanisms of RE in steel were changed to certain degree. Small amount of RE has the effect of cleaning, modifying inclusions and alloying in clean steel, too. With increasing the cleanliness of BNbRE steel, addition of RE should be decreased properly. Under experimental conditions, the optimum addition of RE is -0.01 % （mass fraction） for clean BNbRE steel, while RE can evidently improve plasticity and impact toughness of BNbRE steel.展开更多
The SMART/ASTC dynamic soft reduction technology of VAI and its application on the 6-strand bloom continuous caster at Pangang, China are presented. The operation results show that soft reduction technology is effecti...The SMART/ASTC dynamic soft reduction technology of VAI and its application on the 6-strand bloom continuous caster at Pangang, China are presented. The operation results show that soft reduction technology is effective to improve the inner quality of continuously cast blooms. At Pangang, both the central porosity and the central segregation ratings are no more than 1.0, the central shrinkage cavity rating is no more than 0.5, and the central segregation index of carbon is no more than 1.05. Rails made from the blooms have excellent quality and are used for high-speed tracks.展开更多
In the present study, heavy rail steel was prepared by the process of vacuum induction furnace smelting, forge work and rolling. Effects of Rare earths (RE) on microstructure and mechanical properties of heavy rail st...In the present study, heavy rail steel was prepared by the process of vacuum induction furnace smelting, forge work and rolling. Effects of Rare earths (RE) on microstructure and mechanical properties of heavy rail steel were systematically investigated by metallographic microscope, SEM, integrated mechanical testing machine, impact tester and so on. Metallographic analysis shows that, a few of RE can evidently delay the growth of austenite grain and fine pearlite. When the RE content is 0.016%, both annealing and normalizing pearlite laminae distances reach the minimum which is 115 nm (annealing) and 104nm (normalizing), respectively. But when the RE content reaches 0.133%, the annealing and normalizing pearlite laminae distance is respectively increased by 40% and 13%. Mechanical properties tests show that, a few of RE has not notable effect on the strength, but both plasticity and ductility can be improved obviously. When the RE content is 0.016%, both plasticity and ductility reach maximum. The maximum of elongation and reduction of area is 13.3% and 29.0%, respectively. However, when the RE content reaches 0.133%, the strength, plasticity and ductility are decreased. Especially, the low temperature (-40 ℃) and room temperature (20 ℃) ballistic work is respectively decreased by 9% and 24.8%.展开更多
The mechanisms of La in heavy rail steel were studied by means of experimental measurements, microstructure observation and theoretical analysis in the present work. For heavy rail steel, the state and the content of ...The mechanisms of La in heavy rail steel were studied by means of experimental measurements, microstructure observation and theoretical analysis in the present work. For heavy rail steel, the state and the content of La were measured, and the mechanisms and the effects of La on sulfide inclusions, microstracture and properties of steel were determined. Strip-like sulfides disappear in heavy rail steel with La/（O＋S）〉3.50, which is shown that the metallurgical function of modifying sulfide inclusions has been achieved by La. La can fine the grain size of the austenite in heavy rail steel. Under the experimental condition, the plasticity and the impacting toughness of heavy rail steel with 0.005wt% La can evidently be improved.展开更多
文摘Clean high carbon heavy rail steel was prepared by the process of vacuum induction furnace smelting,forging and rolling.Mechanisms of RE on the impact toughness and fracture toughness for clean high carbon steel were investigated.In addition,the appropriate range of RE content for clean high carbon steel was determined.Both the austenite grain size and pearlite lamellar spacing decreased due to small amount of RE,consequently the impact toughness and fracture toughness were improved evidently.When the RE content exceeded a critical value,the pearlite lamellar spacing was increased,because RE was segregated on the austenite grain boundaries,damaged the orientation relationship of pearlite transformation,caused the disorder growth and morphology degenerating of pearlite.With the increasing of RE content,both the impact toughness and fracture toughness of clean high carbon steel were gradually increased at first and then decreased.It was found that when the RE content was between 0.0081% and 0.0088%,both the impact toughness and fracture toughness of clean high carbon heavy rail steel were the best.The maximum ballistic work was 21.2 J（20 ℃） and 12.2 J（-20 ℃）,respectively.The maximum plane-strain fracture toughness was 45.67 MPa·m1/2（20 ℃） and 37.04 MPa·m1/2（-20 ℃）,respectively.
基金Project supported bythe National Natural Science Fundation of China (50374029)
文摘The mechanisms of RE in clean BNbRE steel were studied by means of experimental measurement, microstructural observation and theoretical analysis. For BNbRE steel, the state and the content of RE were measured, and the effects and the mechanisms of RE on sulfide inclusions, microstructure and properties of steel were determined. On the condition of increasing the cleanliness of steel, the mechanisms of RE in steel were changed to certain degree. Small amount of RE has the effect of cleaning, modifying inclusions and alloying in clean steel, too. With increasing the cleanliness of BNbRE steel, addition of RE should be decreased properly. Under experimental conditions, the optimum addition of RE is -0.01 % （mass fraction） for clean BNbRE steel, while RE can evidently improve plasticity and impact toughness of BNbRE steel.
文摘The SMART/ASTC dynamic soft reduction technology of VAI and its application on the 6-strand bloom continuous caster at Pangang, China are presented. The operation results show that soft reduction technology is effective to improve the inner quality of continuously cast blooms. At Pangang, both the central porosity and the central segregation ratings are no more than 1.0, the central shrinkage cavity rating is no more than 0.5, and the central segregation index of carbon is no more than 1.05. Rails made from the blooms have excellent quality and are used for high-speed tracks.
基金National Science and Technology Ministry (2006BAB02B03, 2006BAE03A04)Key Project of Chinese Ministry of Education (109048)Special Fund for Basic Scientific Research of Central Colleges (N090402017)
文摘In the present study, heavy rail steel was prepared by the process of vacuum induction furnace smelting, forge work and rolling. Effects of Rare earths (RE) on microstructure and mechanical properties of heavy rail steel were systematically investigated by metallographic microscope, SEM, integrated mechanical testing machine, impact tester and so on. Metallographic analysis shows that, a few of RE can evidently delay the growth of austenite grain and fine pearlite. When the RE content is 0.016%, both annealing and normalizing pearlite laminae distances reach the minimum which is 115 nm (annealing) and 104nm (normalizing), respectively. But when the RE content reaches 0.133%, the annealing and normalizing pearlite laminae distance is respectively increased by 40% and 13%. Mechanical properties tests show that, a few of RE has not notable effect on the strength, but both plasticity and ductility can be improved obviously. When the RE content is 0.016%, both plasticity and ductility reach maximum. The maximum of elongation and reduction of area is 13.3% and 29.0%, respectively. However, when the RE content reaches 0.133%, the strength, plasticity and ductility are decreased. Especially, the low temperature (-40 ℃) and room temperature (20 ℃) ballistic work is respectively decreased by 9% and 24.8%.
基金supported by the National Natural Science Foundation of China(No.50374029)and(No.50204005).
文摘The mechanisms of La in heavy rail steel were studied by means of experimental measurements, microstructure observation and theoretical analysis in the present work. For heavy rail steel, the state and the content of La were measured, and the mechanisms and the effects of La on sulfide inclusions, microstracture and properties of steel were determined. Strip-like sulfides disappear in heavy rail steel with La/（O＋S）〉3.50, which is shown that the metallurgical function of modifying sulfide inclusions has been achieved by La. La can fine the grain size of the austenite in heavy rail steel. Under the experimental condition, the plasticity and the impacting toughness of heavy rail steel with 0.005wt% La can evidently be improved.
