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Properties and Microstructure of Laser Welded Dissimilar Joints of TP347-HFG and S235JR Steels with Additional Material

Danielewski H., Skrzypczyk A., Mulczyk K., Zrak A.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 3

1163--1170

EN

Paper presents results of laser welding of dissimilar joints. Flange pipe joints of austenitic TP347-HFG and low carbon S235JR steels were performed. Possibility of laser girth welding of dissimilar joints was presented. Welding of dissimilar materials are complex phenomena, chemical composition of chromium and nickel base austenitic steel with carbon amount of 0.07%, comparing to low carbon steel with trace amount of chromium, nickel and with 0.17% of carbon are different, and affect on welding result. Amount of carbon and chromium have great effect on steel phase transformation and crystallization process, which affect on material hardenability and strength characteristic. In conventional GMA welding methods solidification process of different metals is controlled by use of a selected filler material, for creating buffer zone. The main advantages of laser welding over other methods is process without an additional material, nevertheless some application may require its use. Laser welding with additional material combines advantages of both methods. To carry out weld with high strength characteristic, without welding defects, selecting chemical composition of filler wire are required. Welding parameters was obtained using numerical simulation based on Finite Element Method (FEM). Joint properties was investigated using hardness test. Metallographic analysis of obtained weld was carried out using optical microscopy and energy dispersive spectroscopy (EDS) analysis.

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The Influence of Different Assist Gases on Ductile Cast Iron Cutting by CO2 Laser

Meško J., Nigrovič R., Zrak A.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 4

109--114

EN

This article deals with the technology and principles of the laser cutting of ductile cast iron. The properties of the CO2 laser beam, input parameters of the laser cutting, assist gases, the interaction of cut material and the stability of cutting process are described. The commonly used material (nodular cast iron - share of about 25% of all castings on the market) and the method of the laser cutting of that material, including the technological parameters that influence the cutting edge, are characterized. Next, the application and use of this method in mechanical engineering practice is described, focusing on fixing and renovation of mechanical components such as removing the inflow gate from castings with the desired quality of the cut, without the further using of the chip machining technology. Experimental samples from the nodular cast iron were created by using different technological parameters of laser cutting. The heat affected zone (HAZ), its width, microstructure and roughness parameter Pt was monitored on the experimental samples (of thickness t = 13 mm). The technological parameters that were varied during the experiments included the type of assist gases (N2 and O2), to be more specific the ratio of gases, and the cutting speed, which ranged from 1.6 m/min to 0.32 m/min. Both parameters were changed until the desired properties were achieved.

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An Analysis of the Microstructure, Macrostructure and Microhardness of Nicr-Ir Joints Produced by Laser Welding with and without Preheat

Różowicz S., Tofil S., Zrak A.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2B

1157--1162

EN

This paper discusses some of the basic problems involved in laser welding of dissimilar materials with significant differences in melting points. It focuses on the micro and macrostructure of laser welded NiCr-Ir microjoints used in central spark plug electrodes. The joints were produced by welding with and without preheat using an Nd,YAG laser. The structure and composition of the welded joints were analyzed by means of a light microscope (LM) and a scanning electron microscope (SEM) equipped with an energy dispersive X-ray (EDX) spectrometer. The microhardness of the weld area was also studied.