Influence of heat treatment on microstructures and mechanical properties of K447A cladding layers obtained by laser solid forming

2019 ◽  
Vol 790 ◽  
pp. 703-715 ◽  
Author(s):  
Zhenlin Zhang ◽  
Yue Zhao ◽  
Jiguo Shan ◽  
Aiping Wu ◽  
Huaipeng Gu ◽  
...  
Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 346
Author(s):  
Fei Li ◽  
Bojin Qi ◽  
Yongxin Zhang ◽  
Wei Guo ◽  
Peng Peng ◽  
...  

The steep thermal gradient and complicated thermal cycle occur in the fabrication of Ti6Al4V alloy during laser solid forming (LSF). That leads to obvious anisotropic mechanical properties and requires essential heat treatments to improve its performance. In this work, different heat treatment strategies under vacuum condition were used to study the evolution of microstructures and mechanical properties of Ti6Al4V alloy produced by LSF. The results show that transformation from α phase into lamellar α + β dual-phases structure is introduced at low temperature (550 °C), and the α phase is broken and refined at higher temperature (800 °C). Tensile tests present the increase of elongations in the horizontal and vertical directions by 12.4% and 13.2% for specimens treated by two-step heat treatment (750 °C × 4 h + 500 °C × 1 h). Fatigue crack growth (FCG) lives of LSFed Ti6Al4V alloy after different heat treatments were improved due to the elimination of residual tensile stress and the transformation of α phase into α + β dual-phase structure. Specimens treated at 800 °C for 4 h exhibit a higher fatigue life among those heat-treated alloys. The low sensitivities of the FCG behavior in the Paris-zone to different heat treatments under vacuum condition are explored in the FCG testing of Ti6Al4V alloy.


2007 ◽  
Vol 353-358 ◽  
pp. 715-717
Author(s):  
Jian Peng ◽  
Rong Shen Liu ◽  
Ding Fei Zhang ◽  
Cheng Meng Song

The microstructures and mechanical properties of Mg-Zn-Zr-Y alloy extruded bar with different heat treatment processes were investigated, including solution treatments of 400 oC, 450 oC and 500 oC for 3 hours followed by 170 oC×24h aging treatment, and solely aging treatments of 160 oC, 180 oC for 24hours without solution after extruding. By comparing the grain size, strength and elongation of the samples, the heat treatment processes for extruded products with high strength and with medium strength were recommended.


2016 ◽  
Vol 849 ◽  
pp. 570-579
Author(s):  
Qiang Huang ◽  
Jin Xia Song ◽  
Qing Li ◽  
Wei Peng Ren ◽  
Xin Guang Guan ◽  
...  

The microstructures and mechanical properties of superalloy K465 under different heat treatment, including as as-cast, solution treatment and aging, were investigated. The results showed that γ' precipitates in as-cast condition exhibited two kinds of morphologies of fine regular cuboidal shape at dendritic arm and coarse irregular form in interdendritic region. MC carbides decomposed into M6C carbides partly after 1210°C/4h solution treatment. The high temperature stress-rupture life can be improved obviously with the increasing cooling rate. When cooling rate was lower than 70°C/min, the room temperature tensile elongation increased with cooling rate increasing. When cooling rate was higher than 90°C/min the room temperature tensile elongation decreased with cooling rate increasing. The proper cooling rate of 70oC/min~90oC/min is advantageous for the achievement of excellent comprehensive properties. When aging treatments continued the regularization of γ' resulted in the improvement of stress-rupture life and the reduction of tensile elongation. The mechanical property gap between the solution treatment and aging can be decreased with increasing cooling rate.


2013 ◽  
Vol 690-693 ◽  
pp. 44-48
Author(s):  
Feng Wang ◽  
Zhi Wang ◽  
Zheng Liu ◽  
Ping Li Mao

In this paper, developed a non-aluminum die casting magnesium alloys were studied based on Mg-xGd-Y-Zr(x=6, 8, 12 wt.%)alloys in cold chamber press. The microstructures and mechanical properties of die casting GWK alloys have been investigated using OM, SEM, XRD, EDS and mechanical property test. The experimental results show that with increasing Gd content of Mg-xGd-Y-Zr alloys, the tensile strength increase, but elongation decrease. In particular, die casting GWK alloys after short-term and low-temperature solid solution treatment (T4) have a small variation in grain size and more uniform microstructures, and the second phases distribute at the grain boundaries in form of discontinuous rod shape or granule shape, which result in an obvious improvement in tensile mechanical properties of alloys. The Mg-12Gd-3Y-0.5Zr die casting alloy exhibit maximum tensile strength after solution heat treatment, and the value is 269MPa at room temperature. The effect of solution heat treatment on die casting Mg-xGd-Y-Zr alloys was also discussed.


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