Although 316L stainless steel(SS316L)exhibits favorable ductility and toughness,its limited strength restricts its applicability.This study addressed this limitation by preparing a series of SS316L-xTC4 alloys(where x...Although 316L stainless steel(SS316L)exhibits favorable ductility and toughness,its limited strength restricts its applicability.This study addressed this limitation by preparing a series of SS316L-xTC4 alloys(where x indicates Ti6Al4V(TC4)contents of 0.5 wt%,1 wt%,2 wt%,and 4 wt%)with equiaxed grains,ultrafine grains,and heterogeneous structures using in-situ alloying via laser powder bed fusion.The Ti,Al,and V in the TC4 alloy were shown to stabilize and promote the formation of theαphase,which is stronger than theγphase in typical SS316L.Furthermore,these solute elements readily formed nanoparticles with impurities,such as C and O,to increase the nucleation rate and thereby achieve grain refinement.This resulted in the formation of ultrafine grains predominantly within theαphase,where the solute elements were primarily distributed.The formation of theαphase also impeded the growth of theγphase;coupled with the effects of the nanoparticles,this also significantly reduced the grain size in theγphase.Notably,the SS316L-2TC4 alloy exhibited fully equiaxed grains,and the coexistence of theαandγphases as well as ultrafine and coarse grains formed heterogeneous grain and dual-phase structures within.The synergistic effects of equiaxed grains,ultrafine grains,and heterostructures produced an SS316L alloy that exhibited both excellent strength and elongation.展开更多
The effects of different annealing processes on the phase precipitation behavior and corrosion properties of copper-bearing 430 ferritic stainless steel were systematically investigated.The shape,quantity and distribu...The effects of different annealing processes on the phase precipitation behavior and corrosion properties of copper-bearing 430 ferritic stainless steel were systematically investigated.The shape,quantity and distribution of copper-rich precipitates by different annealing processes were characterized by scanning electron microscopy,transmission electron microscopy,backscatter electron and backscatter diffraction.The pitting resistance behavior in simulated physiological saline envi-ronments(0.9 wt.%NaCl)was investigated using electrochemical workstation and X-ray photoelectron spectroscopy.The results showed that the copper-rich phase prepared by repeated rolling and annealing gradually changed from long needle-like to short thick rod-like and granular,whose distribution tended to be uniform and diffusive,and the number of copper-rich phases increased.After solution/antibacterial annealing process,the size and density of the copper-rich phase increase,resulting in a discontinuity of the passivation film on the stainless steel,which reduces the pitting resistance to some extent.The refinement mechanism revealed that pre-deformation brings about a modification in both precipitation mechanism and growth kinetics of epsilon copper.展开更多
The effects of niobium on the high-temperature oxidation resistance of austenitic stainless steel were systematically investigated.Two austenitic stainless steels with different Nb contents were prepared and exposed t...The effects of niobium on the high-temperature oxidation resistance of austenitic stainless steel were systematically investigated.Two austenitic stainless steels with different Nb contents were prepared and exposed to air at 850℃for 200 h.Results show that Nb positively affects the high-temperature oxidation resistance of austenitic stainless steels.The matrix organization of austenitic stainless steels with added niobium does not change,while the austenitic grain size is significantly refined,and it also promoted the release of internal stresses in the oxide film,which in turn improved the integrity of the oxide film and adhesion to the substrate.In addition,with the addition of Nb element,a large number of Nb(C,N)particles are diffusely distributed in the matrix.Nb(C,N)phase distributed in the matrix and the niobium-rich layer formed by the diffusion of niobium into the interface between the metal matrix and the oxide film during the high-temperature oxidation process effectively prevents the diffusion of iron into the outer layer and enhances the oxidation resistance at high temperatures.展开更多
With the rapid increase in urban gas consumption,the frequency of maintenance and repair of gas pipelines has escalated,leading to a rise in safety accidents during these processes.The traditional manual supervision m...With the rapid increase in urban gas consumption,the frequency of maintenance and repair of gas pipelines has escalated,leading to a rise in safety accidents during these processes.The traditional manual supervision model presents challenges such as inaccurate monitoring results,incomplete risk factor analysis,and a lack of quantitative risk assessment.This research focuses on developing a dynamic risk assessment technology for gas emergency repair operations by integrating the monitoring outcomes of artificial olfactory for gas leakage information and video object recognition for visual safety factor monitoring data.To quantitatively evaluate the risk of the operation process,a three-dimensional risk assessment model combining gas leakage with riskcorrelated sensitivity was established as well as a separate three-dimensional risk assessment model integrating visual risk factors with predictable risk disposition.Furthermore,a visual risk quantification expression mode based on the risk matrix-radar map method was introduced.Additionally,a risk quantification model based on the fusion of visual and olfactory results was formulated.The verification results of simulation scenarios based on field data indicate that the visual-olfactory fusion risk assessment method can more accurately reflect the dynamic risk level of the operation process compared to simple visual safety factor monitoring.The outcomes of this research can contribute to the identification of safety status and early warning of risks related to personnel,equipment,and environmental factors in emergency repair operations.Moreover,these results can be extended to other operational scenarios,such as oil and gas production stations and long-distance pipeline operations.展开更多
基金supported by National Key Research and Development Program of China(Grant No.2022YFB4602301)the National Natural Science Foundation of China(Grant Nos.52405371,52275381,52174346)+1 种基金the Training Program of Innovation and Entrepreneurship for Undergraduates(Grant No.CXCY2024027)We thank Qian Wang(Northwestern Polytechnical University),Yida Feng(Liaocheng University),Jingdong Ma(Liaocheng University),and Keri Xiaoqiangshiyao(Liaocheng University)for their support of this research.
文摘Although 316L stainless steel(SS316L)exhibits favorable ductility and toughness,its limited strength restricts its applicability.This study addressed this limitation by preparing a series of SS316L-xTC4 alloys(where x indicates Ti6Al4V(TC4)contents of 0.5 wt%,1 wt%,2 wt%,and 4 wt%)with equiaxed grains,ultrafine grains,and heterogeneous structures using in-situ alloying via laser powder bed fusion.The Ti,Al,and V in the TC4 alloy were shown to stabilize and promote the formation of theαphase,which is stronger than theγphase in typical SS316L.Furthermore,these solute elements readily formed nanoparticles with impurities,such as C and O,to increase the nucleation rate and thereby achieve grain refinement.This resulted in the formation of ultrafine grains predominantly within theαphase,where the solute elements were primarily distributed.The formation of theαphase also impeded the growth of theγphase;coupled with the effects of the nanoparticles,this also significantly reduced the grain size in theγphase.Notably,the SS316L-2TC4 alloy exhibited fully equiaxed grains,and the coexistence of theαandγphases as well as ultrafine and coarse grains formed heterogeneous grain and dual-phase structures within.The synergistic effects of equiaxed grains,ultrafine grains,and heterostructures produced an SS316L alloy that exhibited both excellent strength and elongation.
基金support of this work by the National Natural Science Foundation of China(51774226)the Major Program of Science and Technology in Shanxi Province(No.20191102006).
文摘The effects of different annealing processes on the phase precipitation behavior and corrosion properties of copper-bearing 430 ferritic stainless steel were systematically investigated.The shape,quantity and distribution of copper-rich precipitates by different annealing processes were characterized by scanning electron microscopy,transmission electron microscopy,backscatter electron and backscatter diffraction.The pitting resistance behavior in simulated physiological saline envi-ronments(0.9 wt.%NaCl)was investigated using electrochemical workstation and X-ray photoelectron spectroscopy.The results showed that the copper-rich phase prepared by repeated rolling and annealing gradually changed from long needle-like to short thick rod-like and granular,whose distribution tended to be uniform and diffusive,and the number of copper-rich phases increased.After solution/antibacterial annealing process,the size and density of the copper-rich phase increase,resulting in a discontinuity of the passivation film on the stainless steel,which reduces the pitting resistance to some extent.The refinement mechanism revealed that pre-deformation brings about a modification in both precipitation mechanism and growth kinetics of epsilon copper.
基金support of this work by the Major Program of Science and Technology in Shanxi Province(202202050201019)the National Natural Science Foundation of China(52271067)Shaanxi Outstanding Youth Fund Project(2021JC-45).
文摘The effects of niobium on the high-temperature oxidation resistance of austenitic stainless steel were systematically investigated.Two austenitic stainless steels with different Nb contents were prepared and exposed to air at 850℃for 200 h.Results show that Nb positively affects the high-temperature oxidation resistance of austenitic stainless steels.The matrix organization of austenitic stainless steels with added niobium does not change,while the austenitic grain size is significantly refined,and it also promoted the release of internal stresses in the oxide film,which in turn improved the integrity of the oxide film and adhesion to the substrate.In addition,with the addition of Nb element,a large number of Nb(C,N)particles are diffusely distributed in the matrix.Nb(C,N)phase distributed in the matrix and the niobium-rich layer formed by the diffusion of niobium into the interface between the metal matrix and the oxide film during the high-temperature oxidation process effectively prevents the diffusion of iron into the outer layer and enhances the oxidation resistance at high temperatures.
基金This work was supported the Key Research and Development Program of Shaanxi Province[2023-YBSF-266]the China Postdoctoral Science Foundation[2021T140544].
文摘With the rapid increase in urban gas consumption,the frequency of maintenance and repair of gas pipelines has escalated,leading to a rise in safety accidents during these processes.The traditional manual supervision model presents challenges such as inaccurate monitoring results,incomplete risk factor analysis,and a lack of quantitative risk assessment.This research focuses on developing a dynamic risk assessment technology for gas emergency repair operations by integrating the monitoring outcomes of artificial olfactory for gas leakage information and video object recognition for visual safety factor monitoring data.To quantitatively evaluate the risk of the operation process,a three-dimensional risk assessment model combining gas leakage with riskcorrelated sensitivity was established as well as a separate three-dimensional risk assessment model integrating visual risk factors with predictable risk disposition.Furthermore,a visual risk quantification expression mode based on the risk matrix-radar map method was introduced.Additionally,a risk quantification model based on the fusion of visual and olfactory results was formulated.The verification results of simulation scenarios based on field data indicate that the visual-olfactory fusion risk assessment method can more accurately reflect the dynamic risk level of the operation process compared to simple visual safety factor monitoring.The outcomes of this research can contribute to the identification of safety status and early warning of risks related to personnel,equipment,and environmental factors in emergency repair operations.Moreover,these results can be extended to other operational scenarios,such as oil and gas production stations and long-distance pipeline operations.
