Abstract: A gradient-structured ultra-fine bainitic low-alloy rail steel and a preparation method thereof are provided in the present application, belonging to the technical field of steel metallurgy. The rail steel to be treated is subjected to three thermal processing treatments so that the gradient-structured ultra-fine bainitic rail steel has a gradient structure consisting of a ferrite-pearlite dual phase microstructure and an ultra-fine bainite microstructure. The gradient structure of the present application enables the matrix of the rail to be a ferrite-pearlite composite phase structure, and only the surface layer of the service surface to be ultrafine bainite.

Abstract: An electrolyte solution and an all-vanadium redox flow battery are disclosed. The electrolyte solution includes: a positive electrode electrolyte solution and a negative electrode electrolyte solution, the positive electrode electrolyte solution and the negative electrode electrolyte solution include chloride ions, sulfate ions and vanadium ions; both the positive electrode electrolyte solution and the negative electrode electrolyte solution satisfy: 2.9?[c(Cl?)+c(SO42?)]/c(Vn+)?3.6; the c(Cl?) represents a concentration of the chloride ions, the c(SO42?) represents a concentration of the sulfate ions, and the c(Vn+) represents a concentration of the vanadium ions. When Cl?, SO42? and Vn+ in the electrolyte solution meet the appropriate concentration relationship, the Cl2 production rate can be greatly reduced, thereby reducing the corrosion of battery materials.

Abstract: A gradient-structured ultra-fine bainitic low-alloy rail steel and a preparation method thereof are provided in the present application, belonging to the technical field of steel metallurgy. The rail steel to be treated is subjected to three thermal processing treatments so that the gradient-structured ultra-fine bainitic rail steel has a gradient structure consisting of a ferrite-pearlite dual phase microstructure and an ultra-fine bainite microstructure. The gradient structure of the present application enables the matrix of the rail to be a ferrite-pearlite composite phase structure, and only the surface layer of the service surface to be ultrafine bainite.

Abstract: The control method for a flow battery includes acquiring a current electrolyte capacity decay rate of the flow battery; comparing the current electrolyte capacity decay rate with a first preset decay rate and a second preset decay rate; when the current electrolyte capacity decay rate is greater than the first preset decay rate and less than the second preset decay rate, adjusting a liquid level of positive electrolyte and a liquid level of negative electrolyte, such that a difference between these two liquid levels is less than a preset value, a ratio of the total amount of vanadium in the positive electrolyte to the total amount of vanadium in the negative electrolyte remains in a first preset ratio range, or a ratio of a vanadium ion concentration in the positive electrolyte to a vanadium ion concentration in the negative electrolyte remains in a second preset ratio range.

Abstract: A heating system for drill steel pipe billet includes a feedback device configured to control distances d1 and d2 of three flamethrowers, a propulsion device, a positioning device, a heating device, a temperature measuring device and a conveying device. Heating temperature of the flamethrowers is controlled by an oxygen distribution box and a gas distribution box. A heating method for the drill steel pipe billet is also provided, in which a rolling forming method of gradient flame heating is adopted to control density of the rolled pieces and avoid internal defects of the drill steel caused by the same deformation of the traditional uniformly heated pipe billets. A radial temperature of the drill steel pipe billet is accurately controlled through the feedback device. Only one set of flamethrowers corresponding to drill steel pipe billets of different dimensions is required, and other devices are universal components, which will not be replaced.

Abstract: The control method for a flow battery includes acquiring a current electrolyte capacity decay rate of the flow battery; comparing the current electrolyte capacity decay rate with a first preset decay rate and a second preset decay rate; when the current electrolyte capacity decay rate is greater than the first preset decay rate and less than the second preset decay rate, adjusting a liquid level of positive electrolyte and a liquid level of negative electrolyte, such that a difference between these two liquid levels is less than a preset value, a ratio of the total amount of vanadium in the positive electrolyte to the total amount of vanadium in the negative electrolyte remains in a first preset ratio range, or a ratio of a vanadium ion concentration in the positive electrolyte to a vanadium ion concentration in the negative electrolyte remains in a second preset ratio range.

Abstract: The control method for a flow battery includes acquiring a current electrolyte capacity decay rate of the flow battery; comparing the current electrolyte capacity decay rate with a first preset decay rate and a second preset decay rate; when the current electrolyte capacity decay rate is greater than the first preset decay rate and less than the second preset decay rate, adjusting a liquid level of positive electrolyte and a liquid level of negative electrolyte, such that a difference between these two liquid levels is less than a preset value, a ratio of the total amount of vanadium in the positive electrolyte to the total amount of vanadium in the negative electrolyte remains in a first preset ratio range, or a ratio of a vanadium ion concentration in the positive electrolyte to a vanadium ion concentration in the negative electrolyte remains in a second preset ratio range.

Abstract: The present invention discloses a heating system for drill steel pipe billet, comprising a feedback device, a propulsion device, a positioning device, a heating device, a temperature measuring device and a conveying device. The distance d1 and d2 of three flamethrowers are controlled through the feedback device. The heating temperature of the flamethrowers is controlled by the oxygen distribution box and the gas distribution box. On the other hand, the present invention also provides a heating method for drill steel pipe billet, which adopts the rolling forming method of gradient flame heating, which realizes the control of the density of the rolled pieces, avoiding the internal defects of the drill steel caused by the same deformation of the traditional pipe billet after uniform heating, improving the quality of the drill steel, and prolonging the service life of the drill steel. The radial temperature of the drill steel pipe billet is accurately controlled through the feedback device.

Abstract: The control method for a flow battery includes acquiring a current electrolyte capacity decay rate of the flow battery; comparing the current electrolyte capacity decay rate with a first preset decay rate and a second preset decay rate; when the current electrolyte capacity decay rate is greater than the first preset decay rate and less than the second preset decay rate, adjusting a liquid level of positive electrolyte and a liquid level of negative electrolyte, such that a difference between these two liquid levels is less than a preset value, a ratio of the total amount of vanadium in the positive electrolyte to the total amount of vanadium in the negative electrolyte remains in a first preset ratio range, or a ratio of a vanadium ion concentration in the positive electrolyte to a vanadium ion concentration in the negative electrolyte remains in a second preset ratio range.