[MW:8343] MW: 8228- SDSS Welding With High Heat Input

 

REPOSTED,

 

Pradip Goswami,P.Eng.IWE

Welding & Metallurgical Specialist & Consultant

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

 

---

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 do not deal with a lot of duplex S.S these days. But in the past for S 31803 welding I'd come across PQR failures, ASTM G-48 especially when the heat input had been on the higher side, typically 2KJ/mm or more. For SDSS good welding specifications would definitely mean a through monitoring of heat input and IPT.

 

The welding process as per this paper  is SAW, SAW is a great welding process,with high degree of reliability. It could be performed with high heat input and with moderate/normal heat input. Certainly for any steel, Low Alloy steel or Austenitic S.S or High Alloy or Duplex S.S , heat input beyond some threshold value with have negative effect on base metal and weld properties.

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.

Pradip Goswami,P.Eng.

Welding & Metallurgical Specialist & Consultant

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

 

---

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

Dear All,

 

I heard that SDSS material shall be welded with a heat input range of 0.5 KJ/mm to 1.5 KJ/mm .Many client specification insisting us to follow this.Recently I got a chance to read one journal regarding SDSS welding with high heat input by SAW process.The result of the study was pretty good.But my client's welding expert says, if the heat input goes above 1.5 KJ/mm,microstructure changes will occur.Experts,what is your opinion on this matter. 

 

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

 

--
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to materials-welding+unsubscribe@googlegroups.com
For more options, visit this group's bolg at http://materials-welding.blogspot.com/
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.