Method for establishing a likelihood of defects in a cast product section

Abstract

A method that allows quality-reducing defects to be detected before the cast product has left a casting plant by establishing a likelihood of defects in a cast product section with a multi-stage product section, the method including multi-step calculations performed in real time. In a first calculation step, at least changes in matrix phase proportions and an element concentration profile in phase regions are calculated in each case for a temperature-time step. The results of the first calculation step are fed to a second calculation step. In the second calculation step, a change in precipitation proportions out of at least one phase region is determined for the subsequent temperature-time step. The results of the second calculation step are used as input variables for the first calculation step. The results of the calculations are used to determine at least one defect index.

1 . A method for establishing a likelihood of defects in a product section cast in a casting plant, wherein a temperature curve over time, for at least one position of a cross section of the product section, was determined during the casting process and is used as an input parameter, wherein
 a multistage product section calculation is carried out on a computer system having a non-transitory computer-readable medium, with the aid of characterizing parameters of the product section and selected operating parameters of the casting plant, wherein the product section calculation runs in real time, the multistage product section calculation comprise of at least the following calculation steps:   a first calculation step, in which at least changes of matrix phase proportions are each calculated for a temperature-time step,   results of the first calculation step are fed to a second calculation step,   wherein in the second calculation step a change of precipitant proportions from at least one phase area is determined,   for the following temperature-time step, results of the second calculation step are used as an input variable for the first calculation step,   wherein results of the product section calculation are used to determine at least one defect index by means of the computer system having the computer-readable medium,   wherein the at least one determined defect index is available in real time, thus immediately before the product section leaves the casting plant.   
     
     
         2 . The method for establishing a likelihood of defects in a product section cast in a casting plant as claimed in  claim 1 , wherein a selection from the following parameters are used as the selected operating parameters:
 casting speeds,   status of the casting machine,   casting powder,   electromagnetic molds and/or casting stirrers,   temperature distribution of the metal within the mold.   
     
     
         3 . The method for establishing a likelihood of defects in a product section cast in a casting plant as claimed in  claim 1 , wherein the product section calculation has a third calculation step in which the diffusion is calculated with the aid of the results of the second calculation step and its results are fed as an input variable to the following first calculation step. 
     
     
         4 . The method for establishing a likelihood of defects in a product section cast in a casting plant as claimed in claimed in  claim 1 , wherein the characterizing parameters of the product section comprise a selection of the following parameters:
 chemical composition   histories of the mechanical tensions and deformations   stretching rates and stretches due to the bending in a bending facility   stretching rates and stretches due to the straightening in a bending facility   stretching rates and stretches due to soft reduction   thermal stretching rates and stretches of the product section within the casting plant.   
     
     
         5 . The method for establishing a likelihood of defects in a product section cast in a casting plant as claimed in  claim 1 , wherein at least the temperature curves of two different positions of the cross section of the cast product section are transmitted as input parameters and likelihoods of defects are determined at least the two positions of the cross section. 
     
     
         6 . The method for establishing a likelihood of defects in a product section cast in a casting plant as claimed in  claim 1 , wherein the characterizing parameters of the product section and the selected operating parameters of the casting plant are determined as a function of operating parameters which are partially or completely determined from the casting process or are calculated during the casting process and made available in real-time to the product section calculation. 
     
     
         7 . The method for establishing a likelihood of defects in a product section cast in a casting plant as claimed in  claim 1 , wherein a change of carbide phase proportions is calculated in the first calculation step. 
     
     
         8 . The method for establishing a likelihood of defects in a product section cast in a casting plant as claimed in  claim 1 , wherein the changes of the precipitant proportions in the phase areas are calculated with the aid of a second thermodynamic equilibrium calculation between matrix phases of an alloy and nonmetallic precipitants. 
     
     
         9 . The method for establishing a likelihood of defects in a product section cast in a casting plant as claimed in  claim 1 , wherein the matrix phase proportions are calculated on the basis of a thermodynamic Gibbs energy approach having thermodynamic equilibrium at one or more phase boundaries and for different phases together with a material equilibrium approach at the phase boundary layer and diffusion. 
     
     
         10 . The method for establishing a likelihood of defects in a product section cast in a casting plant as claimed in  claim 1 , wherein the temperature curve was determined by a calculation and/or a measurement. 
     
     
         11 . A computer program product comprising a non-transitory computer readable-medium having commands recorded thereon which, upon execution by a computer, prompt the computer to carry out the method as claimed in  claim 1 . 
     
     
         12 . A casting plant, preferably a continuous casting plant for producing cast products, preferably slabs, comprising a computer system having a computer-readable medium which comprises a computer program as claimed in  claim 10 . 
     
     
         13 . A computer-readable medium on which the computer program as claimed in  claim 11  is stored. 
     
     
         14 . The method for establishing a likelihood of defects in a product section cast in a casting plant as claimed in  claim 1 , wherein the casting plant is a continuous casting plant. 
     
     
         15 . The method for establishing a likelihood of defects in a product section cast in a casting plant as claimed in  claim 1 , wherein the casting plant is a semi-continuous casting plant. 
     
     
         16 . The method for establishing a likelihood of defects in a product section cast in a casting plant as claimed in  claim 1 , wherein at least four different positions of the cross section of the cast product section are transmitted as input parameters and likelihoods of defects are determined at least in the four positions of the cross section. 
     
     
         17 . The method for establishing a likelihood of defects in a product section cast in a casting plant as claimed in  claim 1 , wherein at least six different positions of the cross section of the cast product section are transmitted as input parameters and likelihoods of defects are determined at least in the six positions of the cross section. 
     
     
         18 . The method for establishing a likelihood of defects in a product section cast in a casting plant as claimed in  claim 1 , wherein the at least one determined defect index is available in real time, thus immediately before the product section reaches a cutting device of the casting plant.