Wyniki wyszukiwania - BazTech

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Wpływ energii liniowej spawania wiązką laserową na mikrostrukturę i wybrane właściwości połączeń ze stali AHSS na przykładzie CPW 800

Różański M., Grajcar A., Stano S

Przegląd Spawalnictwa

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2015

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R. 87, nr 2

23--29

PL

Praca dotyczy problematyki spawania laserowego stali typu CPW 800 z mikrododatkami Ti i Nb. Próby spawania laserowego blach walcowanych termomechanicznie prowadzono techniką głębokiego przetopienia z wykorzystaniem lasera na ciele stałym. Przeprowadzono próby przy różnej energii liniowej procesu, a następnie wykonano badania metalograficzne makroskopowe i mikroskopowe oraz oceniono twardość materiału rodzimego, strefy wpływu ciepła i spoiny. Określono wpływ energii liniowej spawania na szerokość spoiny. Twardość spoiny wynosi około 400 HV1 niezależnie od energii liniowej spawania, a dominującym składnikiem strukturalnym złącza jest martenzyt niskowęglowy. Przedstawiono wyniki badania wytrzymałości na rozciąganie połączeń spawanych.

EN

This study discusses issues related to laser welding of the CPW 800 steel with Ti and Nb microadditions. The tests of laser welding of thermomechanically rolled sheet sampies were carried out using keyhole welding and a solid-state laser. The test s performed for the various values of linear energy were folIowed by macro- and microscopic metallographic investigations as well as by the hardness measurements of base metal, heat-affected zone and fusion weld. The effect of welding linear energy on a weld width has been determined. The weld hardness is approximately 400 HV1 independent on the welding linear energy applied. Low-carbon martensite is a dominant microstructural constituent of the joint. Results of tensile strength test of welded joint were presented.

2

Semi-industrial simulation of hot rolling and controlled cooling of Mn-Al TRIP steel sheets

Grajcar A., Skrzypczyk P., Woźniak D., Kołodziej S.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 57, nr 1

38--47

EN

Purpose: The aim of the work is a semi-industrial physical simulation of thermomechanical rolling and controlled cooling of advanced high-strength steels with increased Mn and Al content. Design/methodology/approach: Four steels of various Mn and Nb concentration were thermomechanically rolled in 3 and 5 passes using a modern LPS line for physical simulation of hot rolling at a semi-industrial scale. The hot deformation course is fully automated as well as controlled cooling applied directly after finishing rolling. Temperature-time and force-energetic parameters of hot rolling were continuously registered and assessed. Findings: The applied line consisting of two-high reversing mill, roller tables with heating panels, cooling devices and controlling-recording systems reflects industrial hot strip rolling parameters sufficiently. Reduction values and temperature-time regimes are similar to those used in industrial practice whereas strain rate is limited to about 10 s-1 what requires taking into account during comparison. All the steels investigated have high total pressure forces due to the high total content of alloying elements. The critical factor making it possible to obtain high-quality sheet samples with a thickness up to 3.3 mm is applying isothermal heating panels which decrease a cooling rate of thin sheets. Research limitations/implications: The real complete simulation of hot strip rolling requires extension of a used line with a further module for simulation of continuous finishing rolling stages. The work is in progress. Practical implications: The results can be successfully utilized in industrial hot rolling and controlled cooling practices after necessary modifications. Originality/value: The efficient semi-industrial physical simulation of hot strip thermomechanical rolling of some new model AHSS grades containing increased Mn and Al content as well as Nb microadditions was presented.

3

Weldability of pulse GMAW joints of 780 MPa dual-phase steel

So W., Kang M., Kim D.

Archives of Materials Science and Engineering

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2010

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Vol. 41, nr 1

53-60

EN

Purpose: This paper assesses the gap bridgeability of pulse GMAW joints of DP 780 for automobile body. Design/methodology/approach: Wire melting was analyzed using a high-speed camera. The impact of EN ratio on the shape of the bead section was examined after analyzing the macrosection of welding which was obtained on a bead-on-plate-welding experiment. Welding conditions that are robust to the gap were suggested through an analysis on tensile strength, macrosection of the weld and fracture appearance of tensile strength testing at the lap joint welding of DP 780. Findings: A relation among the welding current (welding process parameter of AC pulse GMAW), EN ratio, welding speed and bead shape parameters which include bead width, bead height and penetration were computed. Research limitations/implications: The suitable welding conditions proposed in this paper can change because of types of welding joints thickness of base metal and other reasons. Practical implications: In this study, the suitable welding conditions were presented for securing a good weld quality of DP 780 for the automobile body. Originality/value: Through this study, the correlation between the weld bead geometry and the EN ratio in the AC pulse GMAW was confirmed. Though the weld quality assessment, suitable pulse GMAW conditions of DP 780 were suggested.