Since it has excellent tensile strength, the quenching and partitioning （Q ＆ P） treated steel has been widely acclaimed. Some researched is currently being conducted on Q ＆ P steel, but Q ＆ P techniques and relat...Since it has excellent tensile strength, the quenching and partitioning （Q ＆ P） treated steel has been widely acclaimed. Some researched is currently being conducted on Q ＆ P steel, but Q ＆ P techniques and related mechanisms have been mostly research based on conventional transformation-induced plasticity （TRIP） steel. This study researches the effect of Mn on the properties of Q ＆P sheet steel. Two kinds of steel sheet with different levels of Mn content （1.46% Mn and 2.75% Mn） are investigated. After being fully annealed, the steel sheets were quenched to a temperature between Ms and Mr. Allocation treatment then caused the carbon to be partitioned into the remaining austenite.The microstructure and tensile properties were analyzed. The results show that the increment of Mn content can increase the stability of the steel and decrease the sensitivity of the quenching temperature （QT）. The results also indicate that increasing the level of Mn can effectively suppress the formation of bainite.展开更多
In this paper, the influence of plasma arc powder surfacing technical parameters on the property of layer is defined using the orthogonal design. By the orthogonal polynomial regression, when plasma arc powder surfaci...In this paper, the influence of plasma arc powder surfacing technical parameters on the property of layer is defined using the orthogonal design. By the orthogonal polynomial regression, when plasma arc powder surfacing is used on the surface of the X65 steel plate with the Fe-07 alloy powder, the optimum technical parameters are the following: I=180～190 A , G=41.5 g/min , v=102 mm/min , T_0=350 ℃ , Q_l=280 L/h , Q_s=400 L/h . Further, analysis of the cracking test data showed that the cracking preheat temperature is 350 ℃ .展开更多
Simply-supported tied arch is a zero-thrust arch bridge with clear structural force,large stiffness,low height,beautiful appearance and economic efficiency.In Xuzhou-Shanghai section of Beijing-Shanghai HSR,the simply...Simply-supported tied arch is a zero-thrust arch bridge with clear structural force,large stiffness,low height,beautiful appearance and economic efficiency.In Xuzhou-Shanghai section of Beijing-Shanghai HSR,the simply-supported tied arch is systematically studied and widely applied for the first time.A total of 21 simplysupported tied arch bridges with the spans of 96 m,112 m and 128 m respectively are constructed for the route.The simply-supported tied arch is an external static and internal super-static parallel arch or basket arch of Nielsen system in structure;single-box,threechamber and equal-height prestressed concrete box girder is adopted for the tie beam;dumbbell steel pipe concrete section is adopted for the arch rib;PES(FD)low-stress anticorrosion cable body is adopted for the suspender.The rational structural form is determined by comparative study on the key technical parameters such as the layout form of suspender,rise-span ratio and arch axis alignment.This paper summarizes the optimization of simplysupported tied arch structure and looks forward to the development of bridge structure.展开更多
文摘Since it has excellent tensile strength, the quenching and partitioning （Q ＆ P） treated steel has been widely acclaimed. Some researched is currently being conducted on Q ＆ P steel, but Q ＆ P techniques and related mechanisms have been mostly research based on conventional transformation-induced plasticity （TRIP） steel. This study researches the effect of Mn on the properties of Q ＆P sheet steel. Two kinds of steel sheet with different levels of Mn content （1.46% Mn and 2.75% Mn） are investigated. After being fully annealed, the steel sheets were quenched to a temperature between Ms and Mr. Allocation treatment then caused the carbon to be partitioned into the remaining austenite.The microstructure and tensile properties were analyzed. The results show that the increment of Mn content can increase the stability of the steel and decrease the sensitivity of the quenching temperature （QT）. The results also indicate that increasing the level of Mn can effectively suppress the formation of bainite.
文摘In this paper, the influence of plasma arc powder surfacing technical parameters on the property of layer is defined using the orthogonal design. By the orthogonal polynomial regression, when plasma arc powder surfacing is used on the surface of the X65 steel plate with the Fe-07 alloy powder, the optimum technical parameters are the following: I=180～190 A , G=41.5 g/min , v=102 mm/min , T_0=350 ℃ , Q_l=280 L/h , Q_s=400 L/h . Further, analysis of the cracking test data showed that the cracking preheat temperature is 350 ℃ .
文摘Simply-supported tied arch is a zero-thrust arch bridge with clear structural force,large stiffness,low height,beautiful appearance and economic efficiency.In Xuzhou-Shanghai section of Beijing-Shanghai HSR,the simply-supported tied arch is systematically studied and widely applied for the first time.A total of 21 simplysupported tied arch bridges with the spans of 96 m,112 m and 128 m respectively are constructed for the route.The simply-supported tied arch is an external static and internal super-static parallel arch or basket arch of Nielsen system in structure;single-box,threechamber and equal-height prestressed concrete box girder is adopted for the tie beam;dumbbell steel pipe concrete section is adopted for the arch rib;PES(FD)low-stress anticorrosion cable body is adopted for the suspender.The rational structural form is determined by comparative study on the key technical parameters such as the layout form of suspender,rise-span ratio and arch axis alignment.This paper summarizes the optimization of simplysupported tied arch structure and looks forward to the development of bridge structure.
