TY - JOUR N2 - The paper presents results of a study on the effect of passage of time on magnesium content in iron alloys and the effect of magnesium content on the number of vermicular graphite precipitations per unit surface area and value of the longitudinal ultrasonic wave velocity for two different vermicularization methods. The study was carried out with the use of inspection bar castings. For specific production conditions, it has been found that in case of application of both the cored wire injection method and the method of pouring liquid metal over magnesium master alloy on ladle bottom, the satisfactory level of magnesium content in the bottom-pour ladle, for which it was still possible to obtain castings with vermicular graphite, was 0.018% Mg. In case of the cored wire injection method, the “time window” available to a pouring station at which castings of vermicular cast iron are expected to be obtained, was about 5 minutes. This corresponds to the longitudinal ultrasonic wave velocity values exceeding 5500 m/s and the number of graphite precipitations per unit surface area above 320 mm–2. In case of the master alloy method, the respective “time window” allowing to obtain castings of vermicular cast iron was only about 3 minutes long. This corresponds to the longitudinal ultrasonic wave velocity value above 5400 m/s and the number of graphite precipitations per unit surface area above 380 mm–2. L1 - http://journals.pan.pl/Content/116503/PDF/AFE%204_2020_05.pdf L2 - http://journals.pan.pl/Content/116503 PY - 2020 IS - No 4 EP - 40 DO - 10.24425/afe.2020.133345 KW - Vermicular cast iron KW - Vermiculatization method KW - Microstructure KW - Graphite precipitation surface density KW - Longitudinal ultrasonic wave velocity A1 - Tupaj, M. A1 - Orłowicz, A.W. A1 - Mróz, Marek A1 - Kupiec, B. A1 - Pająk, D. A1 - Kawiński, M. PB - The Katowice Branch of the Polish Academy of Sciences VL - vol. 20 DA - 2020.10.12 T1 - Ultrasonic Testing of Vermicular Cast Iron Microstructure SP - 36 UR - http://journals.pan.pl/dlibra/publication/edition/116503 T2 - Archives of Foundry Engineering ER -