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The influence of the distribution of nonmetalic inclusion on the fatigue strength coefficient of high purity steels

Lipiński T.

Journal of Achievements in Materials and Manufacturing Engineering

2015

Vol. 69, nr 1

18--25

Purpose: In this study, attempts were made to analyze the impact of impurities with various diameters and spacing between non-metalic inclusion λ on fatigue strength coefficient k determined under rotary bending fatigue conditions zgo of high purity steels produced in an industrial plant. Design/methodology/approach: 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. The experimental variants were compared in view of the applied melting technology and heat treatment options. The results were presented to account for the correlations between the fatigue strength coefficient during rotary bending, the diameter of and spacing between submicroscopic impurities. Findings: Equations for calculating the fatigue strength coefficient at each tempering temperature and a general equation for all tempering temperatures were proposed. Equations for estimating the fatigue strength coefficient based on the relative volume of submicroscopic non-metallic inclusions were also presented. The relationship between the fatigue strength and hardness of high-grade steel vs. the quotient of the diameter of impurities and the spacing between impurities, and the fatigue strength and hardness of steel vs. the relative volume of non-metallic impurities were determined. Practical implications: The proposed linear regression equations supported the determination of fatigue strength coefficient k and bending fatigue strength as a function of hardness taking into account impurities. Originality/value: The proposed equations contributes to the existing knowledge base of practices impact of impurities with various diameters and spacing between non-metalic inclusion on fatigue strength.

Studies of properties of polypropylene/halloysite composites

Szczygielska A., Kijeński J.

Polish Journal of Chemical Technology

2011

Vol. 13, nr 3

61-65

The results of the studies on the synthesis, mechanical and thermal properties of polypropylene composites with various amount of halloysite filler are presented. Halloysite (HNT) belongs to the silica type characterized by a two-layer 1:1 structure. This work was aimed to develop a method for the modification of halloysite in its prime use as a filler for polypropylene by extrusion. The composites contain 1, 3, 5 and 7 wt.% of HNT. The degree of crystallinity of the composites decrease with increasing halloysite content. The results confirm the expectations that composites of interesting physicochemical, mechanical and thermal properties can be obtained. The mechanical properties studied show that the filler modification method used leads to the synthesis of polymer composites of improved thermal and mechanical properties.