Simulation Of Temperature Field And Research On Temperature Uniformity For Pipeline Steel X80 In Controlled Cooling Process

The progress of pipeline project and pipeline steel smelting technology incresae the demand to a series of performance index such as strenght,impact toughness,reliability.To reduce the final rolling temperature and increase the cooling rate is an effective cooling method to. improve struction and property. At high cooling rate,strip flatness due to temperature inhomogeneity damages steel quality seriously.Therefore,the research on the law of temperature and the temperature uniformity for steel during laminar cooling process is of great significance.Based on the laminar cooling line of a company, the paper first analyses the model of heat transfer and establishes temperature field model for hot strip during laminar cooling based on the theory of calorifics.Numerical simulation of the temperature is achieved by finite difference method.For X80 pipeline steel, the latent heat experiment carried out by differential scanning calorimetry measures DSC curve under different cooling rates.Based on experimental data it can conclude that the relationship described the latent heat and the difference between any temperature within the range of phase transformation and starting temperature conforms to the law of S curves,whose correlation coefficients are obtained by regressing the experimental data.It can also obtain S curve for other steels,such as 40Cr according to the experimental data.The test with experimental data has shown the method is simple and has good agreements with the experimental results.For X80 and above grade pipeline steel, the cooling process requires not only the accuracy of the final rolling temperature, but also the high demand of middle temperature and cooling rate.In this paper,it has analysed the influence of latent heat,strip thickness, water density,water temperature, finishing temperature on middle temperature,cooling rate and end temperature.It provides theory foundation for control on cooling rate and end temperature of pipeling steel.Aiming at temperature inhomogeneity in conditions of low end rolling temperature and high cooling rate,It has analysed the reasons and proposed improved strategy such as altering cooling patter,varying size.The paper deduces the formula which is used to caculate water rate and regress the expression on edge mask and strip width,strip thickness,water density.The temperature homogeneity of strip is controlled well.