Electrochemical corrosion behavior of the laser continuous heat treatment welded joints of 2205 duplex stainless steel |
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Authors: | Heping?Liu Email author" target="_blank">Xuejun?JinEmail author |
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Affiliation: | LIU Heping,JIN Xuejun (School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China) |
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Abstract: | The electrochemical corrosion behaviors of the welded joints of 2205 duplex stainless steel with the laser continuous heat
treatment were investigated. The secondary austenite formation is the outcome of thermodynamic equilibrium breach of the alloy
during heat treatment and the result of the continuous heat treatment which has the most important effect on the weld material.
The partitioning behaviors of chromium and molybdenum as well as the volume fraction of ferrite and austenite have a remarkable
influence on the composition of the individual phase. Mechanical examination of the laser trated weld demonstrates that the
tensile strength and yield strength increase with increasing the amount of the secondary austenite. It is shown that the ultimate
tensile strength of the 6 kW laser-treated weld is higher about 20 MPa than no heat treatment weld and the ductility can be
further improved without compromising strength. The results indicate that the welding alters the corrosion behavior because
of different post heat treatment power and the broad active peak is not identified which is attributed to the dissolution
of the secondary austenitic in the ferrite phase. It is indicated that pitting resistance equivalent (PRE) values of base
metal and 6 kW weld are higher than that of other welds; base metal is 33.7, 6 kW weld 33.3, no treatment 32.4, 4 kW weld
32.8, 8 kW weld 32.5. The extent of corrosion resistance improvement after reheating treatment is mainly caused by the removal
of nitrogen from ferritic regions, which occurred as a consequence of secondary austenite growth. |
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Keywords: | potentiodynamic polarization duplex stainless steel continuous heat treatment secondary austenite |
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