Effect Of The Spacing Between Submicroscopic Oxide Impurities On The Fatigue Strength Of Structural Steel

Abstract

The article discusses the effect of distance between submicroscopic oxide impurities (up to 2 μm in size) on the fatigue resistance coefficient of structural steel during rotary bending. The study was performed on 21 heats produced in an industrial plant. Fourteen heats were produced in 140 ton electric furnaces, and 7 heats were performed in a 100 ton oxygen converter. All heats were desulfurized. Furthermore seven heats from electrical furnaces were refined with argon, and heats from the converter were subjected to vacuum circulation degassing.Steel sections with a diameter of 18 mm were hardened from austenitizing by 30 minutes in temperature 880°C and tempered at a temperature of 200, 300, 400, 500 and 600°C. The experimental variants were compared in view of the applied melting technology and heat treatment options. The results were presented graphically and mathematically. The fatigue resistance coefficient of structural steel with the effect of spacing between submicroscopic oxide impurities was determined during rotary bending. The results revealed that fatigue resistance coefficient k is determined by the distance between submicroscopic non-metallic inclusions and tempering temperature.Keywords: steel, structural steel, non-metallic inclusions, fatigue strength, oxide impurities, fatigue resistance coefficient, bending fatigue, bending pendulum W pracy przedstawiono wyniki badań wpływu odległości pomiędzy submikroskopowymi zanieczyszczeniami tlenkowymi, o wielkości do 2 μm, na wskaźnik odporności na zmęczenie stali konstrukcyjnej przy zginaniu obrotowym. Badania prowadzono na 21 wytopach wyprodukowanych w warunkach przemysłowych. 14 wytopów wykonano w piecach elektrycznych o pojemności 140 ton i 7 wytopów w konwertorze tlenowym o pojemności 100 ton. Wszystkie wytopy poddawano odsiarczaniu. Dodatkowo 7 wytopów pochodzących z pieca elektrycznego poddawano rafinacji argonem, zaś wytopy z konwertora odgazowaniu próżniowemu.Odcinki ze stali o średnicy 18 mm hartowano po austenityzowaniu w czasie 30 minut z temperatury 880°C i odpuszczano w temperaturach: 200, 300, 400, 500 lub 600°C. Warianty badań zestawiono uwzględniając technologię wytapiania stali opcje obróbki cieplnej. Wyniki przedstawiono w graficznej i matematycznej postaci uwzględniającej zależności wskaźnik odporności na zmęczenie przy obrotowym zginaniu z odległości pomiędzy submikroskopowymi zanieczyszczeniami. Wykazano, że wskaźnik odporności na zmęczenie k zależy od odległości pomiędzy submikroskopowymi wtrąceniami niemetalicznymi, oraz temperatury odpuszczania.

APPLICATION OF THE IMAGE ANALYSIS METHODS FOR THE STUDY OF Al2O3 SURAFCE COATINGS

“…Obtained results may be interested for other researchers focused on coatings and surface layer modifications (Skoneczny and Bara, 2007;Bara et al, 2009;Kmita and Bara, 2012;Skoneczny et al, 2018;Bara et al, 2019), even in the combustion technology (Opydo et al, 2016). They may be also inspiring for related areas of materials science (Lipinski, 2015;Lipinski 2018;Szczotok et al, 2018), heavy-duty machines design (Fabis-Domagala et al, 2018) and experimental design methodology (Pietraszek and Goroshko, 2014;Pietraszek et al, 2016), especially with the uncertainty quantification (Pietraszek et al, 2017) and fuzzy logic decision scheme (Filo et al, 2018;Krawczyk and Sobczyk, 2018). The obtained data should be disseminated in scientific databases e.g.…”

Application of the Image Analysis Methods for the Study of Al2O3 Surafce Coatings

“…Obtained results may be interested for other researchers focused on coatings and surface layer modifications (Skoneczny and Bara, 2007;Bara et al, 2009;Kmita and Bara, 2012;Skoneczny et al, 2018;Bara et al, 2019), even in the combustion technology (Opydo et al, 2016). They may be also inspiring for related areas of materials science (Lipinski, 2015;Lipinski 2018;Szczotok et al, 2018), heavy-duty machines design and experimental design methodology (Pietraszek and Goroshko, 2014;Pietraszek et al, 2016), especially with the uncertainty quantification (Pietraszek et al, 2017) and fuzzy logic decision scheme Krawczyk and Sobczyk, 2018). The obtained data should be disseminated in scientific databases e.g.…”

Structure and Chosen Nanomechanical Properties of Amorphous-Crystalline Laser Weld

“…Nucleation and growth of crystalline phases is the fastest to occur in the heat affected zone, as indicated by the initial results of X-ray analysis. This may be caused by the chemical affinity for oxygen of alloy elements of zirconium-based alloys (especially Zr and Al) [6,7] which results in the reduction of the glass-forming ability or a prolonged effect of high temperature on the heat affected zone (HAZ), as well as applying a high pulse energy of the beam laser. Representative results of the cross-sectional analysis of the Zr 55 Cu 30 Ni 5 Al 10 alloy weld obtained with the scanning electron microscope are shown in Fig.…”