| The Jominy hardenability is an important indices for gear steels in order to get a small deformation and high degree of accuracy. The smaller H band and smaller dispersion can obtain a better accuracy. In the china's national standard of GB/T 5216-2004, twenty four grade steels have been tested for hardenability, and the H band is 10~12HRC. But the H band is about 7HRC in the enterprise standard of special steel branch, higher than the china's national standard, inducing some quality problems. The production line consists of a 100-ton DC electric arc furnace(80%scrap steel+20%iron), a ladle refining furnace, a vacuum degassing furnace and a continuous casting machine. The controlled H band is±3.5HRC, through controlling the range of chemical compositions of carbon, manganese, chromium and titanium.There are two factors inducing the high quality problems. First, the above four elements have been controlled singly, which would have a phenomenon of the minimum or the maximum of the four elements at the same time; Secondly, the residual elements of copper, nickel, molybdenum and boron are stable in the long term because of using scrap steel, but the abnormal heat number is existed. So the hardenability will not match the standard sometimes in the long term.In this article, through the empirical equation of hardenability and element, the following models have been researched: linear regression, DI value and artificial neural network. The accuracy of the BP neural network is the most higher in the all models .The most warp is 2.98HRC and the standard deviation is 0.73.Combining the equipment and production requirements, a better effect has been obtained through controlling the DI value in the production.
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