Ural Federal University (Ekaterinburg, Russia):

Parshakov S. I., Cand. Eng., Ass. Prof.

“Novye tekhnologii trub” (“New tube technologies”) LLC (Ekaterinburg, Russia):

Serebryakov Al. V., Cand. Eng., Director

Pervouralsk New Pipe Plant (Pervouralsk, Russia):

Serebraykov An. V., Cand. Eng., Head of Scientifi c Research Dept., Scientifi c Engineering Center, e-mail: andrey.serebryakov@chelpipe.ru
Prilukov S. B., Head of technological Dept.
Maltsev V. V., Cand. Eng., Head of the Shop

Analysis of the yield strength at 350 °C metal tubes, presented for control during the dual-year period, is made. Statistical relations between the control and measuring results of the yield strength and manufacturing date together with chemical composition of the metal melt are analyzed. It is concluded that minimal and maximal values of the yield strength in these tube batches don't exceed allowed deviations. The presented statistical data testifi es about the distinct tendency of variation of the yield strength values, though amplitude of these values is stable during dual-year period, meaning stability of the technological process. Essential relationship between a melt number and parameters of distribution of the yield strength inside the melt has been revealed; it means indirectly about influence of different chemical compositions of melts. Deviation of chemical composition of diff erent melts can be decreased via lowering of phosphorus content and/or elevation of silicon content in the framework of allowed values. It is shown that the replacement of continuous sampling by randomized control does not vary the risk of the consumer substantially. Reliability of obtained results has been confirmed.

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