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Effect of Shielding Gas Composition on Geometry and Austenite Formation in Low Power Pulsed Nd:YAG Laser Welded 2205 Duplex Stainless Steel

Gozarganji Hajibaba, E., Farnia A., Ebrahimnia M.

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 1

187--195

EN

This paper presents an investigation into effect of nitrogen content of shielding gas mixture on weld geometry, microstructure and hardness of pulsed laser welded 2205 duplex stainless steel. Full penetration autogenous welding was performed on 2 mm thick plates using a low power pulsed Nd: YAG laser. light and scanning electron microscopy were used to study the resulting microstructures. It is observed that 2 mm full penetrated joint decreases to 1.8 mm by dominating nitrogen in argon-nitrogen mixture. Different morphologies of austenite phase as well as an increase of 8% of its content can be observed in pure nitrogen shielded welds. Average weld grain size in sample which is welded in nitrogen atmosphere stands at approximately 41 μm which is smallerthan that of argon atmosphere which is about 51 μm. Micro-hardness test reveals that hardness values increase from 280 HV in base metal to 307 HV in weld center line and the shielding gas mixture does not significantly influence the weld hardness.

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Kinetics of the austenite formation during intercritical annealing

Lis J., Lis A.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 26, nr 2

195-198

EN

Purpose: of this paper is the effect of the microstructure of the 6Mn16 steel after soft annealing on the kinetics of the austenite formation during next intercritical annealing. Design/methodology/approach: Analytical TEM point analysis with EDAX system attached to Philips CM20 was used to evaluate the concentration of Mn in the microstructure constituents of the multiphase steel. Findings: The increase in soft annealing time from 1-60 hours at 625*C increases Mn partitioning between ferrite and cementite and new formed austenite and decreases the rate of the austenite formation during next intercritical annealing in the (α+γ) temperature range at 700 and 750*C. Research limitations/implications: The amount of the austenite and final multiphase microstructure can be optimised by changing the time/temperature parameters of the intercritical heating in the (α+γ) temperature range. Originality/value: The knowledge of partitioning of alloying elements mainly Mn during soft annealing is very important to optimise the processing technology of intercritical annealing for a given amount of the austenite.

3

Austenite formation during intercritical annealing

Lis J., Lis A.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 29, nr 1

83-90

EN

Purpose: of this paper is the effect of the soft annealing of initial microstructure of the 6Mn16 steel on the kinetics of the austenite formation during next intercritical annealing. Design/methodology/approach: Analytical TEM point analysis with EDAX system attached to Philips CM20 was used to evaluate the concentration of Mn, Ni and Cr in the microstructure constituents of the multiphase steel and mainly Bainite-Martensite islands. Findings: The increase in soft annealing time from 1-60 hours at 625*C increases Mn partitioning between ferrite and cementite and new formed austenite and decreases the rate of the austenite formation during next intercritical annealing in the (α+γ) temperature range at 700 and 750*C. The general equations for carbide dissolution and austenite formation in intercritical temperature range were established. Research limitations/implications: The final multiphase microstructure can be optimised by changing the time / temperature parameters of the intercritical heating in the (α+γ) temperature range. Originality/value: The knowledge of partitioning of alloying elements mainly Mn during soft annealing and intercritical heating is very important to optimise the processing technology of intercritical annealing for a given amount of the austenite.