Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7963712 | Journal of Nuclear Materials | 2016 | 8 Pages |
Abstract
A nanostructured surface layer was fabricated on commercial pure tungsten using the method of surface mechanical attrition treatment (SMAT). The microstructure evolution of the surface layer was characterized by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and its formation mechanism was discussed as well. Both refinement and elongation of the brittle W grains were confirmed. The elongated SMATed W was heavily strained, the maximum value of the strain at the grain boundaries reaches as high as 3-5%. Dislocation density in the SMATed W nanograins was found to be 5 Ã 1012 cmâ2. The formation of the nanograins in the top surface layer of the W was ascribed to the extremely high strain and strain rate, as well as the multidirectional repetitive loading. Bending strength of commercial W could be improved from 825 MPa to 1850 MPa by SMAT process. Microhardness results indicated the strain range in SMATed W can reach up to 220 μm beneath the top surface. The notched Charpy testing results demonstrated that SMATed W possess higher ductility than that of commercial W. The top surface of the W plates with and without SMATe processing possesses residual compressive stress of about â881 MPa and â234 MPa in y direction, and â872 MPa and â879 MPa in x direction respectively. The improvement of toughness (DBTT shift) of SMATed W may be the synergistic effect of residual compressive stress, dislocation density improvement and microstructure refinement induced by SMAT processing. SMAT processing could be a complementary method to further decrease the DBTT value of tungsten based materials.
Related Topics
Physical Sciences and Engineering
Energy
Nuclear Energy and Engineering
Authors
Hong-Yan Guo, Min Xia, Zheng-Tao Wu, Lap-Chung Chan, Yong Dai, Kun Wang, Qing-Zhi Yan, Man-Chao He, Chang-Chun Ge, Jian Lu,