CN-121983155-A - Method for predicting hydrogen content in steel in vacuum refining process

CN121983155ACN 121983155 ACN121983155 ACN 121983155ACN-121983155-A

Abstract

The invention discloses a method for predicting hydrogen content in steel in a vacuum refining process, which comprises the following steps of collecting vacuum degassing initial working condition parameters, calculating the weight and circulation flow of molten steel in a dual-phase region of a ladle-vacuum chamber, solving the real-time dehydrogenation rate and dehydrogenation accumulation of three dehydrogenation paths of the inside of the molten steel, the free surface of the molten steel and the surface of an argon bubble in a unit time step, establishing a transmission equation of hydrogen concentration in the molten steel circulation process of the two-phase region of the ladle-vacuum chamber based on a mass conservation equation, iteratively solving the hydrogen concentration of the molten steel in the ladle and the vacuum chamber in the unit time by utilizing a fourth-order Dragon-Kutta method, and outputting predicted values of the hydrogen content and real-time hydrogen content change of the molten steel in the ladle through the iteration time step. The method is suitable for vacuum refining devices such as SSRF, RH and the like, the absolute error between the predicted result and the detection value of the on-line hydrogen meter is not more than 0.5ppm, and accurate data support can be provided for process optimization.

Inventors

ZHANG GUOLEI
WANG YANCONG
SHI LEI
HAN PENG
FANG QINGHUA
SONG YONGQUAN
ZHANG ZHONGYANG
QIU MIAN
JIA ZHICHAO
CHEN GANG
SHANG FEI

Assignees

山西太重智能采矿装备技术有限公司
太原重工股份有限公司

Dates

Publication Date: 20260505
Application Date: 20251128

Claims (9)

1. A method for predicting hydrogen content in steel during vacuum refining, comprising the steps of: S1, collecting parameters of vacuum degassing initial working conditions, including initial hydrogen content [ H ] 0 of a steel ladle, molten steel temperature T, molten steel mass W, vacuum chamber pressure Pv, argon blowing flow G and vacuum treatment time T0; Step S2, based on the metallurgical thermodynamic principle and the hydrodynamic equation, based on the mass W of the molten steel and the pressure Pv of the vacuum chamber acquired in the step S1, respectively calculating the weight W L of the molten steel in the two-phase region of the ladle-vacuum chamber and the weight W V of the molten steel in the vacuum chamber, and based on the pressure Pv of the vacuum chamber and the flow G of argon blowing gas acquired in the step S1, calculating the circulation flow of the molten steel in the two-phase region of the ladle-vacuum chamber; S3, constructing a multiphase dehydrogenation reaction coupling equation, respectively calculating real-time dehydrogenation rates of three dehydrogenation paths in the molten steel, the free surface of the molten steel and the surface of the argon bubble in a unit time step, and then calculating the dehydrogenation accumulation amount of the corresponding path based on the calculated real-time dehydrogenation rates of the paths in the unit time step; s4, establishing a transmission equation of hydrogen concentration in the molten steel circulation process of the ladle-vacuum chamber two-phase region based on a mass conservation equation, and solving the hydrogen concentration of the ladle and the molten steel in the vacuum chamber in a unit time step by using a fourth-order Dragon-Kutta method; and S5, repeating the steps S2-S4 until the vacuum treatment time t is over, and outputting the end point hydrogen content in the molten steel and the predicted value of the real-time change of the hydrogen content.
2. The method for predicting hydrogen content in steel in vacuum refining process according to claim 1, wherein in step S2, the weight W V of molten steel in the vacuum chamber is calculated according to the following formula: ; in the above formula: indicating the inner diameter of the vacuum chamber insertion tube; indicating the height of the vacuum chamber insert tube; represents the density of molten steel; The elevation height of the molten steel is represented by the following formula: ; in the above formula: Represents standard atmospheric pressure; representing vacuum chamber pressure; representing gravitational acceleration; The weight W L of the molten steel in the ladle is calculated according to the following formula: ; in the above formula: Indicating the initial molten steel mass.
3. The method for predicting hydrogen content in steel in vacuum refining process as set forth in claim 2, wherein the circulation flow rate of molten steel in two-phase region of ladle-vacuum chamber Calculated according to the following formula: ; wherein: Is a dimensionless constant; indicating the flow rate of argon blowing; indicating the inner diameter of the vacuum chamber insertion tube; Represents standard atmospheric pressure; indicating vacuum chamber pressure.
4. The method for predicting hydrogen content in steel in vacuum refining process as set forth in claim 3, wherein the real-time dehydrogenation rates of three dehydrogenation paths of the interior of molten steel, the free surface of molten steel and the surface of argon bubbles in a unit time step are calculated according to the following formulas, respectively: ; ; ; in the above formula: representing the real-time dehydrogenation rate of the interior of molten steel in a unit time step; k 1 is the dehydrogenation reaction rate constant when the molten steel is nucleated inside; Indicating the weight of molten steel in the vacuum chamber; The [%H ] V is the hydrogen concentration of the molten steel in the vacuum chamber; the equilibrium hydrogen concentration of the molten steel in the vacuum chamber; The method is characterized by comprising the steps of representing real-time dehydrogenation rate of the free surface of molten steel in a unit time step, wherein A 2 is the surface area of a vacuum chamber, and k 2 is the mass transfer coefficient of hydrogen on the free surface of molten steel; representing the real-time dehydrogenation rate of the argon bubble surface in a unit time step; representing the real-time dehydrogenation rate of the argon bubble surface in the ladle in a unit time step; real-time dehydrogenation rate of argon bubble surfaces in a vacuum chamber within a unit time step; A 3 、A 4 is the surface area of argon bubbles in the ladle and the vacuum chamber respectively, and k 3 、k 4 is the mass transfer coefficient of hydrogen entering the argon bubbles in the ladle and the vacuum chamber respectively; The hydrogen concentration of the molten steel in the ladle is shown; is the equilibrium hydrogen concentration of molten steel in the ladle.
5. The method for predicting hydrogen content in steel in vacuum refining process as set forth in claim 4, wherein the dehydrogenation accumulation amounts of three dehydrogenation paths of the interior of molten steel, the free surface of molten steel and the surface of argon bubbles in a unit time step are calculated according to the following formulas, respectively: ; ; ; in the above formula: representing the dehydrogenation accumulation amount in the molten steel in a unit time step; Indicating the weight of molten steel in the vacuum chamber; representing the real-time dehydrogenation rate of the interior of molten steel in a unit time step; Representing the dehydrogenation accumulation of the free surface of the molten steel in a unit time step; representing the real-time dehydrogenation rate of the free surface of molten steel in a unit time step; Representing the dehydrogenation accumulation amount of the argon bubble surface in a unit time step; Representing the dehydrogenation accumulation amount of the argon bubble surface in the ladle in a unit time step; Representing the dehydrogenation accumulation amount of the argon bubble surface in the vacuum chamber in a unit time step; indicating the weight of molten steel in the ladle; representing the real-time dehydrogenation rate of the argon bubble surface in the ladle in a unit time step; real-time dehydrogenation rate per time step of argon bubble surface in vacuum chamber.
6. The method for predicting hydrogen content in steel in vacuum refining process as set forth in claim 5, wherein the equation of transmission of hydrogen concentration in the ladle-vacuum chamber two-phase molten steel circulation process is: ; ; wherein: indicating the weight of molten steel in the ladle; the hydrogen concentration of the molten steel in the ladle is shown; Representing time; The circulating flow of molten steel in the ladle-vacuum chamber two-phase region is represented; the hydrogen concentration of the molten steel in the vacuum chamber; The accumulated dehydrogenation amount of the surface of the ladle argon bubbles in a unit time step is shown; Representing the dehydrogenation accumulation amount of the argon bubble surface of the vacuum chamber in a unit time step; Indicating the weight of molten steel in the vacuum chamber; representing the dehydrogenation accumulation amount in the molten steel in a unit time step; Representing the dehydrogenation accumulation of the free surface of the molten steel in a unit time step; indicating the cumulative amount of dehydrogenation per unit time step at the surface of the argon bubbles in the vacuum chamber.
7. The method for predicting the hydrogen content in steel in the vacuum refining process according to claim 1, wherein in the step S4, the time step value range calculated by the fourth-order longge-kuta method is 0.1-1.0 seconds.
8. The method for predicting hydrogen content in steel in vacuum refining process as claimed in claim 1, wherein the equilibrium hydrogen concentration of molten steel in the vacuum chamber/ladle is calculated by the following formula: ; Wherein K is the equilibrium constant of H 2 generated by chemical reaction of hydrogen atoms, delta G is the Gibbs free energy variation, R is the gas constant; indicating the partial pressure of hydrogen in the molten steel in the vacuum chamber/ladle; Is the temperature of molten steel.
9. The method for predicting the hydrogen content in steel in a vacuum refining process according to claim 1, wherein in step S5, the calculation formula of the hydrogen content in the molten steel is: ; wherein: Indicating the initial hydrogen content of the ladle; representing the dehydrogenation accumulation amount in the molten steel in a unit time step; Representing the dehydrogenation accumulation of the free surface of the molten steel in a unit time step; Indicating the cumulative amount of dehydrogenation at the surface of the argon bubbles per unit time step.

Description

Method for predicting hydrogen content in steel in vacuum refining process Technical Field The invention relates to a method for predicting hydrogen content in steel in a vacuum refining process, and belongs to the technical field of ferrous metallurgy. Background In the field of iron and steel material preparation, hydrogen is used as one of the most destructive impurity elements, and the content control is a technical problem for restricting the production of high-quality steel. When the hydrogen content in steel exceeds a critical value, serious material defects are caused, namely firstly, a hydrogen embrittlement phenomenon is induced, brittle fracture of the steel is caused, the phenomena are particularly represented by deterioration of material extensibility and reduction of area, secondly, hydrogen atoms are offset to form a white spot defect at a crystal boundary, the defect is represented as radial distributed saw-tooth cracks or silver spots at the material fracture, structural continuity of a metal matrix is seriously damaged, moreover, due to higher solubility of hydrogen in liquid steel, bubbles and internal microcracks are formed by the hydrogen precipitated in the solidification process, transverse plasticity and impact toughness of the steel are obviously weakened, and in addition, local enrichment of the hydrogen in a heat affected zone during welding processing induces delayed cracks and promotes subcritical expansion of the steel, so that the fatigue performance of the steel is obviously deteriorated, and finally the service life of a component is greatly shortened. The vacuum refining process is used as a core technical means for controlling dissolved hydrogen in the steel in modern metallurgy, and is particularly critical to controlling the hydrogen content of special steel with high added value such as bearing steel, heavy rail steel, die steel and the like. From thermodynamic analysis, the molten steel hydrogen solubility follows the square root law, i.e. is proportional to the square root of the gas phase hydrogen partial pressure (proportionality constant k≡0.0025 at 1600 ℃), which means that the deep removal of hydrogen content can be achieved by reducing the vacuum chamber pressure below 67 Pa. However, in the actual production process, the dehydrogenation kinetics show obvious nonlinear characteristics, namely, the initial dehydrogenation rate is higher, and the later dehydrogenation rate is obviously slowed down. Although the further reduction of hydrogen content by prolonged treatment times is limited under extreme vacuum conditions, enterprises generally employ long-term treatment schemes that are conservative based on quality stability considerations. The process strategy has three negative effects while guaranteeing the quality, namely, firstly, the energy consumption cost is obviously increased and the equipment loss is accelerated, secondly, the secondary oxidation risk caused by long-time contact of molten steel and refractory materials is increased, and most importantly, large-size inclusions are possibly involved in the continuous strong stirring working condition, and the cleanliness level of the molten steel is damaged. In addition, because of the extremely low hydrogen content and strong diffusivity in molten steel, its accurate measurement faces significant technical challenges. The method mainly adopts three detection methods in the industrial and research fields, has obvious limitations in each characteristic, namely, the method for calculating the hydrogen content of molten steel by using the Sihuamet law based on the thermodynamic equilibrium principle can realize continuous monitoring but is interfered by factors such as molten steel components, temperature and the like, the precision is poor in a low hydrogen content interval, the improved gas chromatography (such as CN202110937557 patent technology) realizes the relative errors of 0.01ppm detection lower limit and less than 5 percent by using innovative steps such as liquid nitrogen preservation, gradient heating, segmented gas collection and the like, and can distinguish hydrogen in different combination states, however, the complex pretreatment flow, the detection period of up to 2 hours and the high equipment investment limit the industrial field application, and the prior art of steel factories can measure the hydrogen content of the molten steel by using a hydrogen determination instrument, and has high acquisition cost and high maintenance cost of a single equipment although the measurement precision is good. Aiming at the defects of the prior art, three common problems mainly exist, namely that most methods belong to offline detection and are difficult to provide real-time guidance for a vacuum refining process, high-precision methods are often complex in equipment and high in cost and are difficult to popularize and apply in industrial sites, and a prediction model for intelligently correlating detect