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10th anniversary of the Dept. of Metallurgical Technologies and Equipment of Nizhniy Novgorod State Technical University n.a. R. E. Alekseev
ArticleName Control of the “Hub” casting forming modes of steel 30KhNML in sand-clay molds and molds from cold-hardening mixtures
DOI 10.17580/chm.2024.01.10
ArticleAuthor E. I. Yarovaya, I. O. Leushin, A. Yu. Gusev
ArticleAuthorData

Nizhny Novgorod State Technical University named after. R. E. Alekseev, Nizhny Novgorod, Russia

E. I. Yarovaya, Cand. Eng., Associate Prof., Dept. of Metallurgical Technologies and Equipment, e-mail: helyar@yandex.ru
I. O. Leushin, Dr. Eng., Prof., Head of the Dept. of Metallurgical Technologies and Equipment, e-mail: igoleu@yandex.ru

 

Russian Federal Nuclear Center of the All-Russian Research Institute of Experimental Physics “Research Institute of Measuring Systems named after. Yu. E. Sedakov”, Nizhny Novgorod, Russia
A. Yu. Gusev, Deputy Chief Designer - Head of Branch Department, e-mail: algus_76@mail.ru

Abstract

Based on the analysis of the change in the strain-stress state of the casting "hub" made of 30KhNML steel formed in sand-clay moulds (SCM) and from cold-hardening mixtures (CHM), it was found that the SCM process is more sensitive to cracking. Stresses in the casting cooled in the SCM-form in the zone of ultimate plastic deformations of steel are higher than in the CHM-form, temperature fluctuations in the volume are 10–15 -С (for SCM), 8–10 °С (for CHM), crack failure is 1–1.5 %. It has been found that these fluctuations can be due to profitable structures in the upper part and the gap between the contact surfaces of the casting and the mold (up to 0.5 mm), which affect heat transfer. Critical stresses in metal were determined at different cooling rates of 0,1–0,35 °С/s in the range of 1480–500°С. Possibility of reducing crack formation is considered based on the analysis of three parameters: cooling rate, internal stresses, heat transfer. For the casting "hub" made of 30KhNML, thermoregulation is necessary, which eliminates temperature differences, shrinkage stresses and cracks. Installation of thermostatic elements, which in the ductility interval provide uniform cooling rate (less than 0,25 °С/s), contact surface corresponding to casting geometry; have low coefficient of linear expansion and thermal conductivity is the solution to the problem.

keywords Steel castings, casting cooling rate, casting stresses, thermostatic elements, alloyed steels, cracks in castings, cold-hardening mixtures molds
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