Straight plates, hollow columns, ear-like blade tips, twist plates withdirectional solidification microstructure made of Rene 95 superalloys were successfully fabricatedon Nickel-base superalloy and DD3 substrates, re...Straight plates, hollow columns, ear-like blade tips, twist plates withdirectional solidification microstructure made of Rene 95 superalloys were successfully fabricatedon Nickel-base superalloy and DD3 substrates, respectively. The processing conditions for productionof the parts with corresponding shapes were obtained. The fabrication precision was high and thecomponents were compact. The solidification microstructure of the parts was analyzed by opticalmicroscopy. The results show that the solidification microstructure is composed of columnardendrites, by epitaxial growth onto the directional solidification substrates. The crystallographyorientation of the parts was parallel to that of the substrates. The primary arm spacing was about10 mum, which is in the range of superfine dendrites, and the secondary arm was small or evendegenerated. It is concluded that the laser metal forming technique provides a method to manufacturedirectional solidification components.展开更多
Rene95 powder and different substrates were selected to be conducted by the laser metal forming technique. It is found that the cladding layers with either columnar or equiaxed grains can be obtained under different s...Rene95 powder and different substrates were selected to be conducted by the laser metal forming technique. It is found that the cladding layers with either columnar or equiaxed grains can be obtained under different solidification conditions. As the crystallography orientation of the substrate influences that of the cladding layers strongly. Multi-grain cladding layers can be obtained on the multi-grain substrate, while directional solidification columnar or even single crystal cladding layer can be achieved on the directional solidification or single crystal substrate.The mechanism of microstructure formation in the cladding layer was furtherly investigated according to the columnar/equiaxed transition profile. In addition,an ear-like single crystal component was manufactured using the DD3 single crystal as substrate. The yield strength at room temperature was examined on the heat-treated slice sample. The results indicate that the yield strength is about 97.9% of that of the powder metallurgical tensile sample while the plasticity overpasses 80% of the powder metallurgical tensile sample.展开更多
Laser multi\|layer cladding experiments were performed on the substrate of DD3 single crystal with FGH95 powder as cladding material.The solidification microstructure in the sample was investigated.It was found that t...Laser multi\|layer cladding experiments were performed on the substrate of DD3 single crystal with FGH95 powder as cladding material.The solidification microstructure in the sample was investigated.It was found that the solidification microstructure was greatly influenced by the crystallography orientation of the substrate and the local solidification conditions.When the angle between the preferred orientation of the single crystal and the direction of heat flow in the cladding layer is less than 30°,single crystal cladding layers were acquired.Otherwise the crystallography orientation of the cladding layer will deviate from the orientation of the substrate and the microstructure with polycrystalline appears.Meanwhile,even when the experiments were performed on the same preferred crystal surface,the solidification microstructures will be different distinctly resulting from the variation of the local solidification conditions.The secondary arms were degenerated and the primary arm spacing was about 10\|20μm.Further investigation shows that the phases of the cladding layer are mainly made up ofγ,γ′,the flower\|likeγ/γ′eutectic and carbide.The morphology ofγ′was cubical and the size is less than 0.1μm.展开更多
Direct laser metal deposition was used for preparing blocks of steel 12CrNi2 using four different laser powers under two different deposition environments including atmospheric environment and Ar-protected chamber.The...Direct laser metal deposition was used for preparing blocks of steel 12CrNi2 using four different laser powers under two different deposition environments including atmospheric environment and Ar-protected chamber.The results showed that microstructures and mechanical properties were significantly affected by different laser powers.Increasing laser power and deposition in Ar chamber will lead to a decrease in the quantity and size of the voids,which brings more elongation to the samples.Bainitic microstructure was replaced by Widmanstatten ferrite and pearlite,and the amount of proeutectoid ferrite increased with increasing laser power.Moreover,microstructures of previous layers were completely altered in high laser power.Excessive heat accumulation by using high heat input can produce equiaxed ferritic grains with the pearlites in previously deposited layers.Hardness of deposited samples increased from the bottom layer toward the top layer.By using a diode laser with a spot diameter size of 2 mm,the 900-W laser power is suitable for producing crack-and void-free samples.However,post-deposition heat treatment is necessary for obtaining homogeneous desired microstructure and grain size in the manufactured samples.展开更多
增材制造技术能够快速将复杂结构的三维数据模型直接转化为实体零部件,是一种快速发展的数字化制造技术。激光增材制造技术是增材制造技术中最具代表性的一类,在增材制造技术领域扮演着重要的角色。主要介绍了两种典型的激光增材制造技...增材制造技术能够快速将复杂结构的三维数据模型直接转化为实体零部件,是一种快速发展的数字化制造技术。激光增材制造技术是增材制造技术中最具代表性的一类,在增材制造技术领域扮演着重要的角色。主要介绍了两种典型的激光增材制造技术:激光选区熔化(Selective Laser Melting,SLM)技术和激光金属直接成形(Laser Metal Direct Forming,LMDF)技术的原理与特点,归纳了其发展和研究现状,指出了激光增材制造技术的发展趋势。展开更多
基金This research was financially supported by the National High Technology Research and Development Program of China (No.2001AA337020)the Development Plan of State Key Fundamental Research of China (No. G2000067205-3)
文摘Straight plates, hollow columns, ear-like blade tips, twist plates withdirectional solidification microstructure made of Rene 95 superalloys were successfully fabricatedon Nickel-base superalloy and DD3 substrates, respectively. The processing conditions for productionof the parts with corresponding shapes were obtained. The fabrication precision was high and thecomponents were compact. The solidification microstructure of the parts was analyzed by opticalmicroscopy. The results show that the solidification microstructure is composed of columnardendrites, by epitaxial growth onto the directional solidification substrates. The crystallographyorientation of the parts was parallel to that of the substrates. The primary arm spacing was about10 mum, which is in the range of superfine dendrites, and the secondary arm was small or evendegenerated. It is concluded that the laser metal forming technique provides a method to manufacturedirectional solidification components.
文摘Rene95 powder and different substrates were selected to be conducted by the laser metal forming technique. It is found that the cladding layers with either columnar or equiaxed grains can be obtained under different solidification conditions. As the crystallography orientation of the substrate influences that of the cladding layers strongly. Multi-grain cladding layers can be obtained on the multi-grain substrate, while directional solidification columnar or even single crystal cladding layer can be achieved on the directional solidification or single crystal substrate.The mechanism of microstructure formation in the cladding layer was furtherly investigated according to the columnar/equiaxed transition profile. In addition,an ear-like single crystal component was manufactured using the DD3 single crystal as substrate. The yield strength at room temperature was examined on the heat-treated slice sample. The results indicate that the yield strength is about 97.9% of that of the powder metallurgical tensile sample while the plasticity overpasses 80% of the powder metallurgical tensile sample.
基金National Key Basic Research Development Program me of china(No.G2000067205-3)
文摘Laser multi\|layer cladding experiments were performed on the substrate of DD3 single crystal with FGH95 powder as cladding material.The solidification microstructure in the sample was investigated.It was found that the solidification microstructure was greatly influenced by the crystallography orientation of the substrate and the local solidification conditions.When the angle between the preferred orientation of the single crystal and the direction of heat flow in the cladding layer is less than 30°,single crystal cladding layers were acquired.Otherwise the crystallography orientation of the cladding layer will deviate from the orientation of the substrate and the microstructure with polycrystalline appears.Meanwhile,even when the experiments were performed on the same preferred crystal surface,the solidification microstructures will be different distinctly resulting from the variation of the local solidification conditions.The secondary arms were degenerated and the primary arm spacing was about 10\|20μm.Further investigation shows that the phases of the cladding layer are mainly made up ofγ,γ′,the flower\|likeγ/γ′eutectic and carbide.The morphology ofγ′was cubical and the size is less than 0.1μm.
基金This work was financially supported by the National Key Research and Development Program of China(No.2016 YFB1100203).
文摘Direct laser metal deposition was used for preparing blocks of steel 12CrNi2 using four different laser powers under two different deposition environments including atmospheric environment and Ar-protected chamber.The results showed that microstructures and mechanical properties were significantly affected by different laser powers.Increasing laser power and deposition in Ar chamber will lead to a decrease in the quantity and size of the voids,which brings more elongation to the samples.Bainitic microstructure was replaced by Widmanstatten ferrite and pearlite,and the amount of proeutectoid ferrite increased with increasing laser power.Moreover,microstructures of previous layers were completely altered in high laser power.Excessive heat accumulation by using high heat input can produce equiaxed ferritic grains with the pearlites in previously deposited layers.Hardness of deposited samples increased from the bottom layer toward the top layer.By using a diode laser with a spot diameter size of 2 mm,the 900-W laser power is suitable for producing crack-and void-free samples.However,post-deposition heat treatment is necessary for obtaining homogeneous desired microstructure and grain size in the manufactured samples.
文摘增材制造技术能够快速将复杂结构的三维数据模型直接转化为实体零部件,是一种快速发展的数字化制造技术。激光增材制造技术是增材制造技术中最具代表性的一类,在增材制造技术领域扮演着重要的角色。主要介绍了两种典型的激光增材制造技术:激光选区熔化(Selective Laser Melting,SLM)技术和激光金属直接成形(Laser Metal Direct Forming,LMDF)技术的原理与特点,归纳了其发展和研究现状,指出了激光增材制造技术的发展趋势。
