Mn-Ti oxides in Si-Mn-Ti deoxidized steels after cooling in the furnace were investigated. The composition and morphology of inclusions were analyzed by using FE-SEM with EDS. Mn-Ti oxides were found to be effective s...Mn-Ti oxides in Si-Mn-Ti deoxidized steels after cooling in the furnace were investigated. The composition and morphology of inclusions were analyzed by using FE-SEM with EDS. Mn-Ti oxides were found to be effective sites to induce intragranular ferrite formation. The thermodynamic calculation was employed to interpret the critical condition for Mn-Ti oxide formation. Mn-Ti oxide formation was controlled not only by Mn and Ti content, but also by total oxygen content in steel. When the Mn and Ti contents were around 1.5% and 0. 005% --0.01%, respectively, Mn-Ti oxide could form as the total oxygen content was 0. 001%- 0. 002 %. The experimental results were in good agreement with thermodynamic calculation results. Also, MnS solubilit：（ was examined in Mn-Ti oxide inclusion system. With an increase of MnO content in Mn-Ti oxide, MnS solubility in the oxides increased. MnS precipitation benefited from high MnO content in Mn-Ti oxide.展开更多
Microstructures and inclusions in the Si-Mn-Ti deoxidized steels after cooling in the furnace were investigated. The composition and morphology of the inclusions were analyzed using a field emission scanning electron ...Microstructures and inclusions in the Si-Mn-Ti deoxidized steels after cooling in the furnace were investigated. The composition and morphology of the inclusions were analyzed using a field emission scanning electron microscope （FE-SEM） with energy dispersive X-ray spectrometry （EDS）. The kind and composition of the inclusions calculated from the thermodynamic database were in good agreement with the experimental results. There were two main kinds of inclusions formed in the Si-Mn-Ti deoxidized steels. One kind of inclusion was the manganese titanium oxide （Mn-Ti oxide）. Another kind of inclusion was the MnS inclusion with segregation points containing Ti and N. According to the thermodynamic calculation, those segregation points were TiN precipitates. The formation of intragranular ferrite （IGF） microstructures refined the grain size during the austenite-ferrite transformation. The mechanisms of IGF formation were discussed. Mn-Ti oxide inclusions with Mn-depleted zone （MDZ） were effective to be nucleation sites for IGF formation, because the MDZ increased the austenite-ferrite transformation temperature. TiN had the low misfit ratio with IGF, so the TiN precipitated on the MnS surface also promoted the formation of IGF because of decreasing interfacial energies.展开更多
The software AnyCasting was used to simulate the thixotropic die-casting process of semi-solid Al-Cu-Mn-Ti alloy slurry to form the parts of a particular shape, especially on how the in-gate size of die and injection ...The software AnyCasting was used to simulate the thixotropic die-casting process of semi-solid Al-Cu-Mn-Ti alloy slurry to form the parts of a particular shape, especially on how the in-gate size of die and injection speed affect the process. The results showed that the die cavity can be filled well with the semi-solid slurry in form of laminar flow under conditions that the temperature of the semi-solid slurry is 640℃ and that of die 200-240℃, thickness of in-gate is 11 mm and, more important, the injection speed should be changed from 0.1 to 1.0 m/s when 60% of die cavity has been filled. The simulation result is highly proved in conformity to the actual die-casting specimens in accordance to the filling process as simulated. Moreover, the hardness of the specimens is up to 116.6 HV after the treatment of solid solution plus underaging, i.e. 45.7% higher than that in conventional ones.展开更多
The composition, morphology, crystalline structure and formation and evolution of X phase in a Cu 12.3Al 2Ni 2Mn 1Ti alloy were studied. The results show that the X phase is a Ti rich phase with atomic ratio of (Cu+Ni...The composition, morphology, crystalline structure and formation and evolution of X phase in a Cu 12.3Al 2Ni 2Mn 1Ti alloy were studied. The results show that the X phase is a Ti rich phase with atomic ratio of (Cu+Ni)∶ Ti∶Al=2∶1∶1 and DO 3 or L2 1 structure; it is directly formed in the liquid phase by crystallization in the process of solidification of the alloy; there forms free particle X phase through the progressive dissolution and breakdown of the inter dendritic microstructure in the following homogenization process. The X phase has three different morphologies, i.e. X L, X LS and X S, whose contents in the matrix rely on the heat treatment conditions. [展开更多
Al-Cu-Mn-Mg合金因其优异的综合性能,被广泛应用于航空航天和轨道交通等领域。然而,该合金在铸造过程中容易出现热裂缺陷,严重影响铸件的质量和可靠性。因此,提高合金的晶粒细化效果,对于改善合金的铸造性能具有重要意义。Al-Ti-B细化...Al-Cu-Mn-Mg合金因其优异的综合性能,被广泛应用于航空航天和轨道交通等领域。然而,该合金在铸造过程中容易出现热裂缺陷,严重影响铸件的质量和可靠性。因此,提高合金的晶粒细化效果,对于改善合金的铸造性能具有重要意义。Al-Ti-B细化剂是铝合金铸造中最常用的晶粒细化剂,但不同Ti/B质量比的Al-Ti-B细化剂对晶粒细化效果及热裂机制尚未系统研究。采用X射线衍射仪(XRD)、光学显微镜(OM)、扫描电镜(SEM)和CRC(constrained rod cast)金属型约束热裂棒模具等,分析了不同Ti/B质量比的Al-Ti-B细化剂对铸造Al-Cu-Mn-Mg合金微观组织和热裂倾向性的影响。实验结果表明,4种Ti/B比的Al-Ti-B细化剂中Al_3Ti和TiB_2相的含量存在显著差异。在B含量均为0.3%(质量分数)的条件下,添加Al-3Ti-1B、Al-4Ti-1B、Al-5Ti-1B和Al-5Ti-2B的Al-5Cu-0.7Mn-0.55Mg合金的平均晶粒尺寸分别为162.07、113.73、107.81和88.00μm,对应的热裂纹倾向性指数依次为112、136、96和24。微观机制分析表明,Ti B_(2)相的含量对晶粒细化效果和热裂倾向性具有显著影响。特别是Al-5Ti-2B细化剂,在晶粒细化的同时,显著降低了合金的热裂倾向性,展现出优异的性能。展开更多
文摘Mn-Ti oxides in Si-Mn-Ti deoxidized steels after cooling in the furnace were investigated. The composition and morphology of inclusions were analyzed by using FE-SEM with EDS. Mn-Ti oxides were found to be effective sites to induce intragranular ferrite formation. The thermodynamic calculation was employed to interpret the critical condition for Mn-Ti oxide formation. Mn-Ti oxide formation was controlled not only by Mn and Ti content, but also by total oxygen content in steel. When the Mn and Ti contents were around 1.5% and 0. 005% --0.01%, respectively, Mn-Ti oxide could form as the total oxygen content was 0. 001%- 0. 002 %. The experimental results were in good agreement with thermodynamic calculation results. Also, MnS solubilit：（ was examined in Mn-Ti oxide inclusion system. With an increase of MnO content in Mn-Ti oxide, MnS solubility in the oxides increased. MnS precipitation benefited from high MnO content in Mn-Ti oxide.
文摘Microstructures and inclusions in the Si-Mn-Ti deoxidized steels after cooling in the furnace were investigated. The composition and morphology of the inclusions were analyzed using a field emission scanning electron microscope （FE-SEM） with energy dispersive X-ray spectrometry （EDS）. The kind and composition of the inclusions calculated from the thermodynamic database were in good agreement with the experimental results. There were two main kinds of inclusions formed in the Si-Mn-Ti deoxidized steels. One kind of inclusion was the manganese titanium oxide （Mn-Ti oxide）. Another kind of inclusion was the MnS inclusion with segregation points containing Ti and N. According to the thermodynamic calculation, those segregation points were TiN precipitates. The formation of intragranular ferrite （IGF） microstructures refined the grain size during the austenite-ferrite transformation. The mechanisms of IGF formation were discussed. Mn-Ti oxide inclusions with Mn-depleted zone （MDZ） were effective to be nucleation sites for IGF formation, because the MDZ increased the austenite-ferrite transformation temperature. TiN had the low misfit ratio with IGF, so the TiN precipitated on the MnS surface also promoted the formation of IGF because of decreasing interfacial energies.
基金the National Natural Science Foundation of China （No. 50374031）the Natural Science Foundation of Liaoning Province （No. 20054003） the Postdoctoral Science Poundation of China （No. 2005038591）.
文摘The software AnyCasting was used to simulate the thixotropic die-casting process of semi-solid Al-Cu-Mn-Ti alloy slurry to form the parts of a particular shape, especially on how the in-gate size of die and injection speed affect the process. The results showed that the die cavity can be filled well with the semi-solid slurry in form of laminar flow under conditions that the temperature of the semi-solid slurry is 640℃ and that of die 200-240℃, thickness of in-gate is 11 mm and, more important, the injection speed should be changed from 0.1 to 1.0 m/s when 60% of die cavity has been filled. The simulation result is highly proved in conformity to the actual die-casting specimens in accordance to the filling process as simulated. Moreover, the hardness of the specimens is up to 116.6 HV after the treatment of solid solution plus underaging, i.e. 45.7% higher than that in conventional ones.
文摘The composition, morphology, crystalline structure and formation and evolution of X phase in a Cu 12.3Al 2Ni 2Mn 1Ti alloy were studied. The results show that the X phase is a Ti rich phase with atomic ratio of (Cu+Ni)∶ Ti∶Al=2∶1∶1 and DO 3 or L2 1 structure; it is directly formed in the liquid phase by crystallization in the process of solidification of the alloy; there forms free particle X phase through the progressive dissolution and breakdown of the inter dendritic microstructure in the following homogenization process. The X phase has three different morphologies, i.e. X L, X LS and X S, whose contents in the matrix rely on the heat treatment conditions. [
文摘Al-Cu-Mn-Mg合金因其优异的综合性能,被广泛应用于航空航天和轨道交通等领域。然而,该合金在铸造过程中容易出现热裂缺陷,严重影响铸件的质量和可靠性。因此,提高合金的晶粒细化效果,对于改善合金的铸造性能具有重要意义。Al-Ti-B细化剂是铝合金铸造中最常用的晶粒细化剂,但不同Ti/B质量比的Al-Ti-B细化剂对晶粒细化效果及热裂机制尚未系统研究。采用X射线衍射仪(XRD)、光学显微镜(OM)、扫描电镜(SEM)和CRC(constrained rod cast)金属型约束热裂棒模具等,分析了不同Ti/B质量比的Al-Ti-B细化剂对铸造Al-Cu-Mn-Mg合金微观组织和热裂倾向性的影响。实验结果表明,4种Ti/B比的Al-Ti-B细化剂中Al_3Ti和TiB_2相的含量存在显著差异。在B含量均为0.3%(质量分数)的条件下,添加Al-3Ti-1B、Al-4Ti-1B、Al-5Ti-1B和Al-5Ti-2B的Al-5Cu-0.7Mn-0.55Mg合金的平均晶粒尺寸分别为162.07、113.73、107.81和88.00μm,对应的热裂纹倾向性指数依次为112、136、96和24。微观机制分析表明,Ti B_(2)相的含量对晶粒细化效果和热裂倾向性具有显著影响。特别是Al-5Ti-2B细化剂,在晶粒细化的同时,显著降低了合金的热裂倾向性,展现出优异的性能。
