From: pgoswami [mailto:pgoswami@quickclic.net]
Sent: Wednesday, November 17, 2010 11:46 PM
To: 'materials-welding@googlegroups.com'
Subject: MW: 8228- SDSS Welding With High Heat Input
Hello Limesh,
You raised an interesting discussion topic. I have attached the article you'd referred to highlighting the salient points.The paper is interesting but the report may not address fully the problems one can experience while welding various types of duplex stainless and super duplex stainless steels. The reasons are as mentioned below:-
- Duplex S.S micro-structure involves a fine balance of ferrite and austenite. As a thumb rule ,too low a heat input causes more of ferritic(less austenite) micro-structure.Too high a heat input will cause re-formation of more of austenite and formation of intermetallic phases. The last one (intermetallics) is more common for SDSS than for DSS.
- Accordingly DSS's have heat input restrictions depending of course on clients' specifications, but typically .05-2.5 KJ/mm and SDSS 's have the same to 0.5-1.5 KJ/mm. See the attached two other papers for info.
I would all said and done if required one may ask the recommendations form the OEM -steel manufacturers or welding consumable manufacturers on the best welding parameters, to select the best welding conditions for this alloy.
If other forum members have "knowledge/ experience base on application of high heat input for DSS/and SDSS it would be appreciated.
Thanks.
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of limesh M
Sent: Friday, November 12, 2010 11:21 PM
To: Materials & Welding
Subject: [MW:8228] SDSS Welding With High Heat Input
Corrosion resistance of SAW duplex joints welded with high heat input
J. Nowacki*, P. Rybicki
Institute of Materials Science and Engineering, Szczecin University of Technology, Al. Piastow 19, 70-310 Szczecin, Poland
Received 19.03.2007; published in revised form 01.08.2007
Abstract
Purpose: test if the welding heat input exceeding the recommended values has negative impact on strength properties and corrosion resistance of the executed welded joints as well as description of influence of the heat input of submerged arc welding (SAW) of duplex steel UNS S31803 (0.032%C, 23.17%Cr, 9.29%Ni, 3.48%Mo, 0.95%Mn, 0.7%Si, 0.16%N, 0.017P, 0.006%S, 0.11%Cu) on welded joints microstructure, particularly average values of ferrite volume fraction, mechanical properties, and corrosion resistance.
Design/methodology/approach: analysis of welding heat input influence on mechanical properties, value of ferrite share, and corrosion of test joints has been done. Non-destructive and destructive testing, e. g. visual examinations, microstructure examination, corrosion resistance tests according to ASTM G48 Method A, HV5 hardness tests, impact and tensile test were carried out. For analysis of welding heat input influence on creation of welding imperfections, there were executed welding of sheet of thickness 9, 14, 28 mm. Butt joints on plates of different thickness were made where the applied heat input of welding exceeded the 2.5 kJ/mm value. Maximum heat input level was HI ≤ 3.0; HI ≤ 3.5; HI ≤ 4.0; HI ≤ 4.5; HI ≤ 5.0.
Findings: based on the performed tests the conclusion is that according to DNV Rules the welding heat input exceeding the recommended values has no negative impact on strength properties and corrosion resistance of the executed welded joints. It was shown that submerged arc welding of duplex steel with the heat input from 2.5 kJ/mm up to 5.0 kJ/mm has no negative influence on properties of the joints.
Research limitations/implications: the welding heat input exceeding the recommended values may influenced the precipitation processes in the HAZ, what need further experiments.
Practical implications: application of high value of the welding heat input will be profitable in terms of the welding costs.
Originality/value: an original value of the paper is to prove that a usage of high value welding heat input provides the best joints quality.
Regards,
Limesh
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