The microstructure of lneonel 601 nickel-based superalloy after gas tungsten arc welding and its transformation at different solution temperatures are studied. The results show that the original microstructure of weld...The microstructure of lneonel 601 nickel-based superalloy after gas tungsten arc welding and its transformation at different solution temperatures are studied. The results show that the original microstructure of weld seam is characterized coarsened austenitic granular crystal, there are a large amount of dispersed carbide and γ＇ phase with carbide as the core in the boundary of grains. Grain of heat-affected zone grows up severely with very little precipitated carbide. The carbide and γ＇ phase are gradually solved into the austenite matrix with the increase of solution treatment temperature. Especicdly solution treated at 1 150 ℃, the carbide and γ＇ phase are completely solved into the austenite matrix, the coarsened equiaxed anstenite grain sizes are refined.展开更多
Laser oscillating welding was employed to fabricate Al-Si coated press-hardened steel(PHS)to improve the element homogeneity in the fusion zone.Laser oscillating welding was employed with various oscillation amplitude...Laser oscillating welding was employed to fabricate Al-Si coated press-hardened steel(PHS)to improve the element homogeneity in the fusion zone.Laser oscillating welding was employed with various oscillation amplitudes(0 mm,0.5 mm and 1.3 mm)in this present.Ni foil of 0.06 mm thickness was used as an interlayer between two tailored PHS welded.The weld morphology,elemental profile,microstructure and tensile strength of welded joints were studied.The results showed that full penetration weld without any weld defects were achieved for any oscillation amplitudes,and weld width increased with increasing oscillation amplitudes.With the oscillation amplitudes increased,Ni and Al had an uneven elemental profile due to strong stirring force,but the Ni and Al content in the weld was decreased and Ni had a sharp descent compared to Al element.Only fewδ-ferrite was presented in fusion line with the oscillation amplitudes increased to 1.3 mm.The oscillation amplitudes did not have an effect on the tensile properties,which was similar to that of base metal.But if keeping increasing the oscillation amplitudes or reducing the thickness of Ni interlayer,it has a potential risk to form more and moreδferrite such that deteriorate the mechnical properties of welded joints.展开更多
In this study,the selective laser melting(SLM)technology has been employed to manufacture a nickelbased superalloy which was conventionally prepared through powder metallurgy(PM)route.The microstructural features and ...In this study,the selective laser melting(SLM)technology has been employed to manufacture a nickelbased superalloy which was conventionally prepared through powder metallurgy(PM)route.The microstructural features and defects were systematically investigated both prior to and after heat treatment and compared with the PM counterpart.Both solidification cracking and liquation cracking were observed in the SLM specimen in which the grain misorientation and low melting point(γ+γ')eutectic played a vital role in their formation mechanism.Columnar grains oriented along building direction were ubiquitous,corresponding to strong<001>fiber texture.Solidification cell structures and melt pools are pervasive and noγ'precipitates were detected at about 10 nm scale before heat treatment.After supersolvus solution and two-step aging treatments,high volume fractionγ'precipitates emerged and their sizes and morphologies were comparable to those in PM alloy.<001>texture is relieved and columnar grains tend to become more equiaxed due to static recrystallization process and grain boundary migration events.Significant annealing twins formed in SLM alloy and are clarified as a consequence of recrystallization.Our results provide fundamental understandings for the SLM PM nickel-based superalloy both before and after heat treatment and demonstrate the potential to fabricate this group of alloys using SLM technology.展开更多
As a primary material of the thorium molten salt reactor（TMSR） that is a suitable candidate reactor of the Generation IV nuclear reactors, GH3535 superalloy was successfully welded. The effect of laser beam welding...As a primary material of the thorium molten salt reactor（TMSR） that is a suitable candidate reactor of the Generation IV nuclear reactors, GH3535 superalloy was successfully welded. The effect of laser beam welding（LBW） on microstructure evolution of fusion zone（FZ） and heat affected zone（HAZ）, such as element segregation, precipitate behavior and grain evolution, was investigated. The microhardness and tensile properties were tested and discussed. The results of microstructure evolution showed that a number of fine M6C-y eutectic phases precipitated at solidification grain boundaries and interdendritic region in FZ. Compared to base metal zone（BMZ）, the grain size of HAZ has no obvious change. While a few of M6C-y eutectic phases were observed in partially melted zone（PMZ） of HAZ. The results of microhardness indicated that the hardness of FZ was higher than that of HAZ and BMZ. The results of tensile test showed that the ultimate tensile strength of joints at room temperature, 650 and 700？C were98%, 97% and 99% of that of BM, respectively. All the tensile specimens of joints failed in BMZ rather than in PMZ where M6 C carbides had been transformed into M6C-y eutectic phases.展开更多
以0.26 mm V+0.2 mm Cu复合薄片作为过渡层,采用激光焊方法连接TiAl/GH3030异质高温合金,对接头的宏观和微观组织的形貌、物相、力学性能及断口进行分析。结果表明:添加过渡层可实现TiAl/GH3030异质高温合金的良好连接,焊缝成形后外观...以0.26 mm V+0.2 mm Cu复合薄片作为过渡层,采用激光焊方法连接TiAl/GH3030异质高温合金,对接头的宏观和微观组织的形貌、物相、力学性能及断口进行分析。结果表明:添加过渡层可实现TiAl/GH3030异质高温合金的良好连接,焊缝成形后外观良好。焊缝区主要形成了白色(V,Cr)固溶体相、灰色等轴片层状AlNi 2Ti/(V,Cr)共晶组织、黄色晶间块状相Ni基固溶体(Ni,Cu)、浅黄色晶间相Cu基固溶体(Cu,Ni)。GH3030合金侧界面区未形成金属间化合物层,而TiAl合金侧形成了由AlCuTi和AlCu 2Ti构成的金属间化合物层,且界面层存在微裂纹缺陷。接头的平均抗拉强度为202 MPa,接头断裂于TiAl合金侧,AlCuTi和AlCu_(2)Ti金属间化合物相是导致接头脆化、力学性能降低的主要原因。展开更多
基金The work was supported by the National High Technology Research and Development Program of China （ No. 2008AAO4Z136 ）, National Natural Science Foundation of China （50975197）, Tianjin Municipal Science and Technology Commission of China （09JCZDJC24000）.
文摘The microstructure of lneonel 601 nickel-based superalloy after gas tungsten arc welding and its transformation at different solution temperatures are studied. The results show that the original microstructure of weld seam is characterized coarsened austenitic granular crystal, there are a large amount of dispersed carbide and γ＇ phase with carbide as the core in the boundary of grains. Grain of heat-affected zone grows up severely with very little precipitated carbide. The carbide and γ＇ phase are gradually solved into the austenite matrix with the increase of solution treatment temperature. Especicdly solution treated at 1 150 ℃, the carbide and γ＇ phase are completely solved into the austenite matrix, the coarsened equiaxed anstenite grain sizes are refined.
基金National Natural Science Foundation of China(Grant No.52005357)“Qinglan”Project of Jiangsu Province of China,and Jiangsu Provincial Natural Science Foundation of China(Grant No.BK 20180984).
文摘Laser oscillating welding was employed to fabricate Al-Si coated press-hardened steel(PHS)to improve the element homogeneity in the fusion zone.Laser oscillating welding was employed with various oscillation amplitudes(0 mm,0.5 mm and 1.3 mm)in this present.Ni foil of 0.06 mm thickness was used as an interlayer between two tailored PHS welded.The weld morphology,elemental profile,microstructure and tensile strength of welded joints were studied.The results showed that full penetration weld without any weld defects were achieved for any oscillation amplitudes,and weld width increased with increasing oscillation amplitudes.With the oscillation amplitudes increased,Ni and Al had an uneven elemental profile due to strong stirring force,but the Ni and Al content in the weld was decreased and Ni had a sharp descent compared to Al element.Only fewδ-ferrite was presented in fusion line with the oscillation amplitudes increased to 1.3 mm.The oscillation amplitudes did not have an effect on the tensile properties,which was similar to that of base metal.But if keeping increasing the oscillation amplitudes or reducing the thickness of Ni interlayer,it has a potential risk to form more and moreδferrite such that deteriorate the mechnical properties of welded joints.
基金the financial support from the National Science and Technology Major Project of China (No. J2019-VI-0004-0117)National Natural Science Foundation of China (No. 51905301)。
基金supported financially by the National Key Research and Development Program of China(No.2018YFB0704100)the Outstanding Graduate Project of Advanced Non-ferrous Metal Structural Materials and Manufacturing Collaborative Innovation Center+2 种基金the Funding from the Opening Project of State Key Laboratory of Nickel and Cobalt Resources Comprehensive Utilizationthe Project of Innovation and Entrepreneur Team Introduced by Guangdong Province(No.201301G0105337290)the Special Funds for Future Industrial Development of Shenzhen(No.HKHTZD20140702020004)。
文摘In this study,the selective laser melting(SLM)technology has been employed to manufacture a nickelbased superalloy which was conventionally prepared through powder metallurgy(PM)route.The microstructural features and defects were systematically investigated both prior to and after heat treatment and compared with the PM counterpart.Both solidification cracking and liquation cracking were observed in the SLM specimen in which the grain misorientation and low melting point(γ+γ')eutectic played a vital role in their formation mechanism.Columnar grains oriented along building direction were ubiquitous,corresponding to strong<001>fiber texture.Solidification cell structures and melt pools are pervasive and noγ'precipitates were detected at about 10 nm scale before heat treatment.After supersolvus solution and two-step aging treatments,high volume fractionγ'precipitates emerged and their sizes and morphologies were comparable to those in PM alloy.<001>texture is relieved and columnar grains tend to become more equiaxed due to static recrystallization process and grain boundary migration events.Significant annealing twins formed in SLM alloy and are clarified as a consequence of recrystallization.Our results provide fundamental understandings for the SLM PM nickel-based superalloy both before and after heat treatment and demonstrate the potential to fabricate this group of alloys using SLM technology.
基金supported by National Key Research and Development Program of China (Grant No. 2016YFB0700404)the National Natural Science Foundation of China (Grant Nos. 51371188, 51671122, 51671154, 51501216, 51601213)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA02004210)
文摘As a primary material of the thorium molten salt reactor（TMSR） that is a suitable candidate reactor of the Generation IV nuclear reactors, GH3535 superalloy was successfully welded. The effect of laser beam welding（LBW） on microstructure evolution of fusion zone（FZ） and heat affected zone（HAZ）, such as element segregation, precipitate behavior and grain evolution, was investigated. The microhardness and tensile properties were tested and discussed. The results of microstructure evolution showed that a number of fine M6C-y eutectic phases precipitated at solidification grain boundaries and interdendritic region in FZ. Compared to base metal zone（BMZ）, the grain size of HAZ has no obvious change. While a few of M6C-y eutectic phases were observed in partially melted zone（PMZ） of HAZ. The results of microhardness indicated that the hardness of FZ was higher than that of HAZ and BMZ. The results of tensile test showed that the ultimate tensile strength of joints at room temperature, 650 and 700？C were98%, 97% and 99% of that of BM, respectively. All the tensile specimens of joints failed in BMZ rather than in PMZ where M6 C carbides had been transformed into M6C-y eutectic phases.
文摘以0.26 mm V+0.2 mm Cu复合薄片作为过渡层,采用激光焊方法连接TiAl/GH3030异质高温合金,对接头的宏观和微观组织的形貌、物相、力学性能及断口进行分析。结果表明:添加过渡层可实现TiAl/GH3030异质高温合金的良好连接,焊缝成形后外观良好。焊缝区主要形成了白色(V,Cr)固溶体相、灰色等轴片层状AlNi 2Ti/(V,Cr)共晶组织、黄色晶间块状相Ni基固溶体(Ni,Cu)、浅黄色晶间相Cu基固溶体(Cu,Ni)。GH3030合金侧界面区未形成金属间化合物层,而TiAl合金侧形成了由AlCuTi和AlCu 2Ti构成的金属间化合物层,且界面层存在微裂纹缺陷。接头的平均抗拉强度为202 MPa,接头断裂于TiAl合金侧,AlCuTi和AlCu_(2)Ti金属间化合物相是导致接头脆化、力学性能降低的主要原因。
