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1

Welding thermal cycles of joints made of S1100QL steel by saw and hybrid plasma-mag processes

Sajek A.

Advances in Materials Science

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2020

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Vol. 20, nr 4(66)

75--86

EN

The aim of this article is to validate the method of conducting a multipoint temperature measurement in the area of welded joints as a tool for quality assessment of the joints in question. In order to establish a relationship between temperature readout at a given point, the value of heat input and the distance of the point form the weld axis, preliminary tests have been conducted on a set of padding welds. Correlation of measurement data analysis showed the high 0.99 level. In the second stage of the study, temperatures of joints welded with two different methods have been measured: the HPAW (Hybrid Plasma – Arc Welding) and classic SAW (Submerged Arc Welding) method. The obtained temperature curves reflect the intensity of heat input in a given welding process. When compared to thermal effects on metallographic specimens, the shapes of the curves show a potential for quality assessment of joints in production conditions. Estimating thermal effects with classic analytical methods proves imprecise with respect to advanced high-power welding processes. Monitoring temperature will allow to assess the quality of joints in the course of welding, which may be a remarkable factor in terms of limiting the HAZ (heat affected zone) tempering of joints made from MART steels (advanced high strength martensitic steel) – a phenomenon that exceedingly decreases the strength of the joints. The method for quality assessment of welded joints presented in this paper allows to extend the analysis of welding thermal conditions.

2

The Effect of Fine Non-Metallic Inclusions on the Fatigue Strength of Structural Steel

Lipiński T., Wach A.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 1

65--69

EN

The article discusses the results of a study investigating the effect of the number of fine non-metallic inclusions (up to 2 µm in size) on the fatigue strength 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. 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 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 the fatigue strength of steel with a varied share of non-metallic inclusions was determined during rotary bending. The results revealed that fatigue strength is determined by the relative volume of fine non-metallic inclusions and tempering temperature.

PL

W pracy przedstawiono wyniki badań wpływu ilości drobnych wtrąceń niemetalicznych, o wielkości do 2 µm, na wytrzymałość zmęczeniową 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. 7 wytopów pochodzących z pieca elektrycznego poddawano rafinacji argonem, zaś wytopy z konwertora odgazowaniu próżniowemu. Odcinki ze stali o średnicy 18 mm hartowano 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 postaci uwzględniającej zależności wytrzymałości zmęczeniowej przy obrotowym zginaniu z udziałem objętościowym wtrąceń niemetalicznych. Wykazano, że wytrzymałość zmęczeniowa zależy od objętości względnej drobnych wtrąceń niemetalicznych, oraz temperatury odpuszczania.

3

Computer modelling system of the chemical composition and treatment parameters influence on mechanical properties of structural steels

Dobrzański L. A., Honysz R.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 35, nr 2

138-145

EN

Purpose: This paper presents Neuro-Lab. It is an authorship programme, which use algorithms of artificial intelligence for structural steels mechanical properties estimation. Design/methodology/approach: On the basis of chemical composition, parameters of heat and mechanical treatment and elements of geometrical shape and size this programme has the ability to calculate the mechanical properties of examined steel and introduce them as raw numeric data or in graphic as influence charts. Possible is also to examine the dependence among the selected steel property and chosen input parameters, which describes this property. Findings: There is no necessity of carrying out any additional material tests. The results correlations between calculated and measured values are very good and achieve even the level of 98%. Practical implications: Presented programme can be an effective replace of the real experimental methods of properties determination in laboratory examinations. It can be applied as the enlargement of experimental work. Possible is also the investigation of models coming from new steel species, that wasn’t produced yet. Originality/value: The ability of the mechanical properties estimation of the ready, or foreseen to the use, material is unusually valuable for manufacturers and constructors. This signifies the fulfilment of customer’s quality requirements as well as measurable financial advantages for material manufacturers.

4

Cold forming techniques for the manufacture of steel structual sections

Macdonald M., Heiyantuduwa M., Harrison D. K.

Przegląd Mechaniczny

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2008

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nr 2

40-43