Entity

Time filter

Source Type

Chaoyang, China

Wang L.,Shanghai JiaoTong University | Qu J.,Shanghai JiaoTong University | Chen L.,Shanghai JiaoTong University | Meng Q.,Beijing FSW Technology Co. | And 4 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2015

Friction-stir processing (FSP) is used to prepare Ti-35Nb-2Ta-3Zr alloys via different processing routes. Dislocation walls and tangles, deformation-induced α″ martensite, and deformation-induced ω phase are observed. The dominant deformation mechanisms are altered from deformation-induced α″ martensitic transformation and dislocation walls to twinning upon increasing the FSP passes. A reverse deformation-induced ω to β transformation and de-twinning process are observed together with grain refinement to the nanoscale. Meanwhile, compressive distortions along [0001]ω direction are favorable for the transformation from ω to β. © 2015 The Minerals, Metals & Materials Society and ASM International Source


Luo R.,Jiangsu University | Cheng X.-N.,Jiangsu University | Li D.-S.,Jiangsu University | Xu G.-F.,Jiangsu University | And 4 more authors.
Gongneng Cailiao/Journal of Functional Materials | Year: 2014

The tendency to intergranular corrosion of the welded joints of 800H and Cr18Ni30Mo2Al3Nb alloy was investigated. Sensitizing treatment of 650℃ ×100 h and no treatment was used. The microstructure, morphology and the intergranular corrosion resistance of samples were studied by optical microscope, SEM and Method of copper sulfate-sulfuric acid test for stainless steels. The results show that the dissimilar welded joints are all the single austenite (γ) organizations. TiN inclusions lead to pitting corrosion in alloy 800H. However, no excessive pitting corrosion in Cr18Ni30Mo2Al3Nb alloy. As can be seen from the weightlessness, corrosion depth test results, clearly shown that Cr18Ni30Mo2Al3Nb welded joint has better intergranular corrosion resistance than 800H. ©, 2014, Journal of Functional Materials. All right reserved. Source


Xu W.F.,Northwestern Polytechnical University | Liu J.H.,Northwestern Polytechnical University | Chen D.L.,Ryerson University | Luan G.H.,Beijing FSW Technology Co.
International Journal of Advanced Manufacturing Technology | Year: 2014

Strain-controlled low-cycle fatigue tests and microstructural evaluation were performed on a friction stir welded 2219-T62 aluminum alloy with varying welding parameters and cooling conditions. Cyclic hardening of friction stir welded joints was appreciably stronger than that of the base material. The cyclic stress amplitude increased, and plastic strain amplitude and fatigue lifetime slightly decreased with increasing welding speed from 60 to 200 mm/min but were only weakly dependent of the rotational rate between 300 and 1,000 rpm with air cooling. Friction stir welded joints with water cooling had higher stress amplitude and fatigue life than that with air cooling. Fatigue failure of the joint occurred in the HAZ where the soft zone was present, with crack initiation from the specimen surface or near-surface defect and crack propagation characterized by typical fatigue striations. © 2014 Springer-Verlag London. Source


Xu W.,Northwestern Polytechnical University | Liu J.,Northwestern Polytechnical University | Chen D.,Ryerson University | Luan G.,Beijing FSW Technology Co. | Yao J.,Shanghai Aerospace Equipments Manufacturer
Advanced Materials Research | Year: 2011

Microstructures, tensile properties and work hardening behavior of friction stir welded (FSWed) AA2219-T62 aluminum alloy (in its one-third bottom slice of a 20 mm thick plate) were evaluated at different strain rates. While the yield strength was lower in the FSWed joint than in the base metal, the ultimate tensile strength of the FSWed joint approached that of the base metal. In particular the FSW resulted in a significant improvement in the ductility of the alloy due to the prevention of premature failure caused by intergranular cracking along the second-phase boundary related to the presence of the network-like grain boundary phase in the base metal. While stage III and IV hardening occurred after yielding in both base metal and FSWed samples, the FSW led to stronger hardening capacity and higher strain hardening exponent and rate due to the enhanced dislocation storage capacity associated with the microstructural change after FSW. The fracture surface of the FSWed joint was mainly characterized by dimples and tearing ridges along with micropores. © (2011) Trans Tech Publications, Switzerland. Source


Xu W.F.,Northwestern Polytechnical University | Liu J.H.,Northwestern Polytechnical University | Chen D.L.,Ryerson University | Luan G.H.,Beijing FSW Technology Co. | Yao J.S.,Shanghai Aerospace Equipments Manufacturer
Materials Science and Engineering A | Year: 2012

Microstructures, tensile properties and strain hardening behavior of a friction stir welded (FSWed) thick AA2219 aluminum alloy under optimized welding parameters and varying cooling conditions (air cooling and water cooling) were investigated with three slices (top, middle and bottom) through the plate thickness. While the yield strength was lower in the FSWed joints than in the base metal, the ultimate tensile strength of the FSWed joints with water cooling reached nearly that of the base metal. In particular, FSW resulted in a significant improvement in the ductility of the alloy due to the presence of recrystallized fine grains with fragmented and uniformly dispersed second-phase particles in the weld nugget zone. Water cooling resulted in both higher strength and ductility, but lower strain hardening capacity than that with air cooling during FSW. Compared with the middle and bottom slices, the top slice had a higher strength, but lower ductility and strain hardening capacity. While stages III and IV hardening occurred after yielding in both base metal and FSWed samples, the FSW led to higher hardening capacity and strain hardening rate and exponent mainly in the middle and bottom slices. The fracture surfaces after FSW exhibited more obvious ductile fracture characteristics with dimples and tearing ridges along with micropores. © 2012. Source

Discover hidden collaborations