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Research on Deep-Hole Drilling of High-Strength Steel Using Slender Gun Dril
Jiabin Liang,Li Jiao,Pei Yan,Minghui Cheng,Tianyang Qiu,Xibin Wang 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.23 No.8
There are a lot of problems in the processing of deep hole gun drilling of high strength steel, such as difficulty in selecting machining parameters, unknown influence mechanism of machining parameters on drilling force, drilling temperature and machining quality. In this paper, 42CrMo high strength steel is selected as the workpiece material. A numerical model of cutting force is established based on the mechanism of gun drill, and then the finite element simulation and processing test are carried out. The results show that the cutting force decreases with the increase of cutting speed, and increases with the increase of feed speed; the error between the theoretical and actual value is less than 10%. The shape and position accuracy of the entrance end is higher than that of the exit end, but the surface quality is the opposite. Cutting speed and feed speed have a great influence on machining quality, and the cutting fluid pressure mainly affects the surface roughness.
Enhancing the Ag Precipitation by Surface Mechanical Attrition Treatment on Cu-Ag Alloys
Jiabin Liu,Lehao Zhang,Jingjing Liu,Liuyi Huang,Hao Gu,Youtong Fang,Liang Meng,Jian Zhang 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.5
The influence of surface mechanical attrition treatment (SMAT) on Ag precipitation in Cu-Ag alloys was investigated. Cu-6 wt% Ag was melt, cold rolled and solution treated to be Cu-Ag solid solution, which was either aged at 250 and 350 °C for 24 h directly or SMAT-ed before aging. Ag precipitates were hard be found in the directly aged Cu-Ag sample while they were observed clearly in the SMAT-ed counterpart at 250 °C. The Ag precipitates formed in the surface layer by SMAT are much coarser than those in the un-SMAT-ed sample. It is obvious that the precipitating behavior of Ag was promoted significantly by SMAT approach. A large number of defects were generated by SMAT and they were acting as fast atomic diffusion channels that facilitated the atomic diffusion of Ag.