The effect of shot peening（SP） on hydrogen embrittlement of high strength steel was investigated by electrochemical hydrogen charging, slow strain rate tensile tests, and hydrogen permeation tests. Microstructure ob...The effect of shot peening（SP） on hydrogen embrittlement of high strength steel was investigated by electrochemical hydrogen charging, slow strain rate tensile tests, and hydrogen permeation tests. Microstructure observation, microhardness, and X-ray diffraction residual stress studies were also conducted on the steel. The results show that the shot peening specimens exhibit a higher resistance to hydrogen embrittlement in comparison with the no shot peening（NSP） specimens under the same hydrogen-charging current density. In addition, SP treatment sharply decreases the apparent hydrogen diffusivity and increases the subsurface hydrogen concentration. These findings are attributed to the changes in microstructure and compressive residual stress in the surface layer by SP. Scanning electron microscope fractographs reveal that the fracture surface of the NSP specimen exhibits the intergranular and quasi-cleavage mixed fracture modes, whereas the SP specimen shows only the quasi-cleavage fractures under the same hydrogen charging conditions, implying that the SP treatment delays the onset of intergranular fracture.展开更多
Shot blasting on a tube steel of TP304H can greatly improve the oxidation resistance at *50°C—770°C in water vapor, by the presence of an appropriate blasting intensity. SEM and EPMA analysis indicated that...Shot blasting on a tube steel of TP304H can greatly improve the oxidation resistance at *50°C—770°C in water vapor, by the presence of an appropriate blasting intensity. SEM and EPMA analysis indicated that the structure of the oxide scale turned from multi-layer to monolayer after blasting and Cr2O3 in predominant. The untreated sample characterized in multi-layer oxide was composed of Fe in the outer layer and Fe and Cr underneath. For blasted one, the increase of diffusion rate of Cr and the decrease of effective diffusion energy of scale led to a uniform Cr-rich oxide layer, which was dense and protective and the oxidation resistance was increased.展开更多
The aim of the work was to find out how the modification of surface treatment and microstructures affect the fatigue characteristics of the considered sintered materials. Two different systems were prepared： as-sinte...The aim of the work was to find out how the modification of surface treatment and microstructures affect the fatigue characteristics of the considered sintered materials. Two different systems were prepared： as-sintered and shot peened prealloyed sintered （Astaloy CrL based） steels with addition of 0.5% and 0.7% C. Sintering was carried out in laboratory tube furnace in an atmosphere of pure gases 75%N2＋25%H2. The sintering temperature was 1180℃ and sintering time was 60 min. Heating and cooling rates were 10℃/min. Fatigue tests were carried out in symmetric plane bending at stress ratio R=-1 with frequency of about 24 Hz. The presented experimental results showed that prealloyed water-atomised steels, with surface modification, exhibit positive effects on the fatigue failure resistance, and for that reason are suitable for high-performance applications.展开更多
The corrosion behavior of TP304H steel with combined treatment of shot blasting and electrophoresis deposited RE coating in l%SO2+14%O2+85%Ar mixture gaseous has been studied at 923K for 150 hours. The results show th...The corrosion behavior of TP304H steel with combined treatment of shot blasting and electrophoresis deposited RE coating in l%SO2+14%O2+85%Ar mixture gaseous has been studied at 923K for 150 hours. The results show that both RE coating and shot blasting can improve the corrosion resistance of TP304H steel, and combined treatment has the best effect. Combined treatment reduces 50% mass gain, enhances the continuous and compactness of scale and changes the scale phase forms from FeaOs/Fe^S/Ni^/S to Cr2O3/FeCr2S4/Ni3_xS2. The synergistic effects of combined treatment on corrosion resistance and the effect of shot blasting on corrosion kinetics are discussed. Shot blasting increases the outward diffusion and surface concentration of Cr, Ce coating promotes the selective oxidation of Cr.展开更多
Shot peening is one of the most popular surface enhancement technique used to improve fatigue performance of different materials. This paper focuses on to study the effect of different shot peening parameters on micro...Shot peening is one of the most popular surface enhancement technique used to improve fatigue performance of different materials. This paper focuses on to study the effect of different shot peening parameters on micro-structural and mechanical properties of DIN 1.2714 tool steel specimens. Shot peening treatments were carried out by varying shot size and peening intensity. X-ray stress analysis, micro-hardness testing and micro-structural analysis were performed to characterize these specimens. In addition, pin on disk wear testing was executed to recognize wear behavior of this shot peened tool steels. It was observed that along with compressive residual stress generation, shot peening also induces work hardening effect and modifies surface structure which are responsible for significant improvement in this tool steel.展开更多
基金financially supported by the Doctoral Research Assistant Foundation of Xi'an Jiaotong University
文摘The effect of shot peening（SP） on hydrogen embrittlement of high strength steel was investigated by electrochemical hydrogen charging, slow strain rate tensile tests, and hydrogen permeation tests. Microstructure observation, microhardness, and X-ray diffraction residual stress studies were also conducted on the steel. The results show that the shot peening specimens exhibit a higher resistance to hydrogen embrittlement in comparison with the no shot peening（NSP） specimens under the same hydrogen-charging current density. In addition, SP treatment sharply decreases the apparent hydrogen diffusivity and increases the subsurface hydrogen concentration. These findings are attributed to the changes in microstructure and compressive residual stress in the surface layer by SP. Scanning electron microscope fractographs reveal that the fracture surface of the NSP specimen exhibits the intergranular and quasi-cleavage mixed fracture modes, whereas the SP specimen shows only the quasi-cleavage fractures under the same hydrogen charging conditions, implying that the SP treatment delays the onset of intergranular fracture.
文摘Shot blasting on a tube steel of TP304H can greatly improve the oxidation resistance at *50°C—770°C in water vapor, by the presence of an appropriate blasting intensity. SEM and EPMA analysis indicated that the structure of the oxide scale turned from multi-layer to monolayer after blasting and Cr2O3 in predominant. The untreated sample characterized in multi-layer oxide was composed of Fe in the outer layer and Fe and Cr underneath. For blasted one, the increase of diffusion rate of Cr and the decrease of effective diffusion energy of scale led to a uniform Cr-rich oxide layer, which was dense and protective and the oxidation resistance was increased.
基金research project CNR-SAS and project VEGA 2/6209/26
文摘The aim of the work was to find out how the modification of surface treatment and microstructures affect the fatigue characteristics of the considered sintered materials. Two different systems were prepared： as-sintered and shot peened prealloyed sintered （Astaloy CrL based） steels with addition of 0.5% and 0.7% C. Sintering was carried out in laboratory tube furnace in an atmosphere of pure gases 75%N2＋25%H2. The sintering temperature was 1180℃ and sintering time was 60 min. Heating and cooling rates were 10℃/min. Fatigue tests were carried out in symmetric plane bending at stress ratio R=-1 with frequency of about 24 Hz. The presented experimental results showed that prealloyed water-atomised steels, with surface modification, exhibit positive effects on the fatigue failure resistance, and for that reason are suitable for high-performance applications.
文摘The corrosion behavior of TP304H steel with combined treatment of shot blasting and electrophoresis deposited RE coating in l%SO2+14%O2+85%Ar mixture gaseous has been studied at 923K for 150 hours. The results show that both RE coating and shot blasting can improve the corrosion resistance of TP304H steel, and combined treatment has the best effect. Combined treatment reduces 50% mass gain, enhances the continuous and compactness of scale and changes the scale phase forms from FeaOs/Fe^S/Ni^/S to Cr2O3/FeCr2S4/Ni3_xS2. The synergistic effects of combined treatment on corrosion resistance and the effect of shot blasting on corrosion kinetics are discussed. Shot blasting increases the outward diffusion and surface concentration of Cr, Ce coating promotes the selective oxidation of Cr.
文摘Shot peening is one of the most popular surface enhancement technique used to improve fatigue performance of different materials. This paper focuses on to study the effect of different shot peening parameters on micro-structural and mechanical properties of DIN 1.2714 tool steel specimens. Shot peening treatments were carried out by varying shot size and peening intensity. X-ray stress analysis, micro-hardness testing and micro-structural analysis were performed to characterize these specimens. In addition, pin on disk wear testing was executed to recognize wear behavior of this shot peened tool steels. It was observed that along with compressive residual stress generation, shot peening also induces work hardening effect and modifies surface structure which are responsible for significant improvement in this tool steel.
