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Hot Formability of Heat-Resistant Stainless Steel X15CrNiSi20-12

Kawulok R., Schindler I., Navrátil H., Ševčák V., Sojka J., Konečná K., Chmiel B.

Archives of Metallurgy and Materials

2020

Vol. 65, iss. 2

727--734

High-temperature plastic properties of heat-resistant stainless steel X15CrNiSi20-12 were assessed on the basis of hot tensile tests and nil strength tests. The results were supported by metallographic analyses using SEM and EDX analysis. The formability of the investigated steel can be divided into roughly three temperature areas. In the temperature range of 900°C to about 1050°C, formability was negatively affected by precipitation of carbide particles at grain boundaries. As the temperature rose to 1200°C, these particles dissolved, resulting in an increase in formability. Further temperature increases resulted in a relatively steep drop in formability caused by overheating of the material. The nil ductility temperature of 1280°C and the nil-strength temperature of 1362°C were determined. The Plastic and strength properties of the investigated material were compared with the deformation behavior of the reference steel X5CrNi18-10, which shows a significantly wider range of suitable forming temperatures.

Alternative Evaluation of the Properties of the Silica Sands

Beňo J., Mikšovský F., Jelinek P., Konečná K., Smysl P.

Archives of Metallurgy and Materials

2014

Vol. 59, iss. 2

735--738

For the evaluation of silica sands, which belongs to the most employed sands of foundry molding mixtures, there are a number of methods and techniques to characterize their quality. This implies good knowledge of their strengths and weaknesses. However, a small proportion of published results are dedicated to the impact of transport on transport routes in the foundry and the processes of dry reclamation on the properties of the silica sands, in particular on changes to the granulometry and the formation of undesirable dust sands shares, which significantly affect the properties of the sand mixture. The aim of this contribution is the evaluation of inclination of the silica sand to crush (the formation of dust, change the granulometry) according to the newly developed methodology with regard to its nature of sand (genesis, the shape of the grains, the character of the surface).

Piaski kwarcowe stanowią podstawowe tworzywo na osnowę mas formierskich i rdzeniowych. Stąd istnieje bardzo wiele metod charakteryzujących ich jakość, co umożliwia poznanie ich zalet i wad. Mało jest jednak prac opisujących wpływ systemów transportowych odlewni oraz systemów suchej regeneracji mas na zmianę ich składu granulometrycznego oraz zawartości frakcji pylastych na właściwości mas. Celem niniejszej pracy jest ocena skłonności piasku kwarcowego do rozkruszania, (tworzenia frakcji pyłowych i zmianie granulometrii) według nowo opracowanej metodyki uwzględniającej charakterystyczne cechy piasku wynikające z jego pochodzenia, kształty ziaren i charakteru powierzchni.

Micro and macrocracking of rolls in cold rolling mills

Titz K., Konečná K., Špok M., Tvrdý M.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

2008

z. 92

61-62