Stainless steels are used in a wide range of complex environments due to their excellent corrosion resistance.Multiphase stainless steels can offer an excellent combination of strength,toughness and corrosion resistan...Stainless steels are used in a wide range of complex environments due to their excellent corrosion resistance.Multiphase stainless steels can offer an excellent combination of strength,toughness and corrosion resistance due to the coexistence of different microstructures.The microstructure and mechanical properties of a novel cast multiphase stainless steel,composed of martensite,ferrite,and austenite,were investigated following appropriate heat treatment processes:solution treatment at 1,050℃ for 0.5 h followed by water quenching to room temperature,and aging treatment at 500℃ for 4 h followed by water quenching to room temperature.Results show reversed austenite is formed by diffusion of Ni element during aging process,and the enrichment of Ni atoms directly determines the mechanical stability of austenite.The austenite with a lower Ni content undergoes a martensitic transformation during plastic deformation.The tensile strength of the specimen exceeds 1,100 MPa and the elongation exceeds 24%after solid solution,and further increases to 1,247 MPa and 25%after aging treatment.This enhancement is due to the TRIP effect of austenite and the precipitation of the nanoscale G-phase pinning dislocations in ferrite and martensite.展开更多
Foreign tourists'trips to China recently reached a new height,both online and offline.Travel agents around the world also made trips to China,generating more thoughts for the development of new routes and the desi...Foreign tourists'trips to China recently reached a new height,both online and offline.Travel agents around the world also made trips to China,generating more thoughts for the development of new routes and the design of innovative tourist products,and contributing to the development of China's inbound tourism.展开更多
A high-current vacuum arc （HCVA） with the consideration of anode vapor is modeled and simulated. First, from the HCVA column model, the heat flux density to the anode is obtained, which is put into the anode activit...A high-current vacuum arc （HCVA） with the consideration of anode vapor is modeled and simulated. First, from the HCVA column model, the heat flux density to the anode is obtained, which is put into the anode activity model, and the parameter distributions （such as the vapor temperature and velocity） of anode vapor are obtained from the simulation results of the anode activity model. Then, by iterating and calculating the HCVA column model and anode activity model, the interaction between the HCVA column and the anode vapor is simulated and analyzed. In the simulation, the distribution of the axial magnetic field （AMF） generated by the electrode system is calculated by software ANSYS. The simulation results show that the influence of anode vapor on the parameter distributions in the arc column is significant. The simulation results are also compared with the vacuum arc photograph.展开更多
The gradual advances of offshore oil and gas exploitation and the development tendency of equipment integration have prompted the design of a new type of the high-current composite umbilical to meet development needs....The gradual advances of offshore oil and gas exploitation and the development tendency of equipment integration have prompted the design of a new type of the high-current composite umbilical to meet development needs.In order to study the mechanical behavior of the high-current composite umbilical(HCCU)and provide design suggestions,a theoretical analysis framework of the tension-torsion coupled behavior of the spirally wound structure is proposed,which focuses more on the radial mechanical behavior.Then,by considering the mechanical and thermal conditions during the operation of HCCU,a semi-analytical method of the tension and torsion stiffness of the high-current composite umbilical considering the temperature effect is established.Furthermore,a practical case of HCCU is given,and the thermal effect on the radial and axial mechanical behaviors are analyzed.It is found that the thermal effect has a significant influence on the radial stiffness,and shows non-linear variation characteristics.Finally,the sensitivity analysis is carried out to study the influence of the design parameter on the stiffness of tension and torsion.The results indicated that the equivalent radial stiffness and helical angle have obvious effect on the tension-torsion coupled stiffness,which can provide reasonable reference for the design of HCCU.展开更多
The present paper reports the rapid surface alloying induced by the bombardment of high-current pulsed electron beam. Two kinds of substrate materials were examined to show this effect. The first sample was a pure Al ...The present paper reports the rapid surface alloying induced by the bombardment of high-current pulsed electron beam. Two kinds of substrate materials were examined to show this effect. The first sample was a pure Al metal pre-coated with fine carbon powders prior to the bombardment, and the second alloy is the D2-Crl2MolVl mould steel pre-coated with Cr, Ti, and TiN powders. The surface elements diffuse about several micrometers into the substrate materials only after several bombardments. Tribological behaviors of these samples were characterized and significant improvement in wear resistance was found. Finally, a TEM analysis reveals the presence of stress waves generated by coupled thermal and stress fields, which was considered as the main cause of the enhanced properties.展开更多
基金supported by the Inner Mongolia Autonomous Region Science and Technology Major Special Project(Grant No.2021SZD0082).
文摘Stainless steels are used in a wide range of complex environments due to their excellent corrosion resistance.Multiphase stainless steels can offer an excellent combination of strength,toughness and corrosion resistance due to the coexistence of different microstructures.The microstructure and mechanical properties of a novel cast multiphase stainless steel,composed of martensite,ferrite,and austenite,were investigated following appropriate heat treatment processes:solution treatment at 1,050℃ for 0.5 h followed by water quenching to room temperature,and aging treatment at 500℃ for 4 h followed by water quenching to room temperature.Results show reversed austenite is formed by diffusion of Ni element during aging process,and the enrichment of Ni atoms directly determines the mechanical stability of austenite.The austenite with a lower Ni content undergoes a martensitic transformation during plastic deformation.The tensile strength of the specimen exceeds 1,100 MPa and the elongation exceeds 24%after solid solution,and further increases to 1,247 MPa and 25%after aging treatment.This enhancement is due to the TRIP effect of austenite and the precipitation of the nanoscale G-phase pinning dislocations in ferrite and martensite.
文摘Foreign tourists'trips to China recently reached a new height,both online and offline.Travel agents around the world also made trips to China,generating more thoughts for the development of new routes and the design of innovative tourist products,and contributing to the development of China's inbound tourism.
基金supported by National Natural Science Foundation of China (No. 50907045)
文摘A high-current vacuum arc （HCVA） with the consideration of anode vapor is modeled and simulated. First, from the HCVA column model, the heat flux density to the anode is obtained, which is put into the anode activity model, and the parameter distributions （such as the vapor temperature and velocity） of anode vapor are obtained from the simulation results of the anode activity model. Then, by iterating and calculating the HCVA column model and anode activity model, the interaction between the HCVA column and the anode vapor is simulated and analyzed. In the simulation, the distribution of the axial magnetic field （AMF） generated by the electrode system is calculated by software ANSYS. The simulation results show that the influence of anode vapor on the parameter distributions in the arc column is significant. The simulation results are also compared with the vacuum arc photograph.
基金financially supported by the National Key R&D Program of China(Grant No.2021YFA1003501)the National Natural Science Foundation of China(Grant Nos.U1906233 and 52001088)+1 种基金the Key R&D Program of Shandong Province(Grant No.2019JZZY010801)the Fundamental Research Funds for the Central Universities(Grant Nos.DUT20ZD213 and DUT20LAB308)。
文摘The gradual advances of offshore oil and gas exploitation and the development tendency of equipment integration have prompted the design of a new type of the high-current composite umbilical to meet development needs.In order to study the mechanical behavior of the high-current composite umbilical(HCCU)and provide design suggestions,a theoretical analysis framework of the tension-torsion coupled behavior of the spirally wound structure is proposed,which focuses more on the radial mechanical behavior.Then,by considering the mechanical and thermal conditions during the operation of HCCU,a semi-analytical method of the tension and torsion stiffness of the high-current composite umbilical considering the temperature effect is established.Furthermore,a practical case of HCCU is given,and the thermal effect on the radial and axial mechanical behaviors are analyzed.It is found that the thermal effect has a significant influence on the radial stiffness,and shows non-linear variation characteristics.Finally,the sensitivity analysis is carried out to study the influence of the design parameter on the stiffness of tension and torsion.The results indicated that the equivalent radial stiffness and helical angle have obvious effect on the tension-torsion coupled stiffness,which can provide reasonable reference for the design of HCCU.
文摘The present paper reports the rapid surface alloying induced by the bombardment of high-current pulsed electron beam. Two kinds of substrate materials were examined to show this effect. The first sample was a pure Al metal pre-coated with fine carbon powders prior to the bombardment, and the second alloy is the D2-Crl2MolVl mould steel pre-coated with Cr, Ti, and TiN powders. The surface elements diffuse about several micrometers into the substrate materials only after several bombardments. Tribological behaviors of these samples were characterized and significant improvement in wear resistance was found. Finally, a TEM analysis reveals the presence of stress waves generated by coupled thermal and stress fields, which was considered as the main cause of the enhanced properties.
