Preheat and interpass temp

[sftyvlv]

On our weld data sheets at work we have all the parameters to do a given job, accompanying this is a PQR and WPS.
My question is concerning preheat and interpass heat values. Depending on the material,how do they arrive at these values and are they based on upper and lower critical temps.
Sftyvlv

 

[metengr]

sftyvlv;
There are various Codes and Standards (AWS, NBIC, ASME B&PV Code) that provide guidance for recommended preheat temperature based on thickness and base metal chemical composition. I have also found various sources that provide recommended interpass temperatures based on heat input restrictions. For example, when welding austenitic stainless steels or duplex stainless steels, interpass temperatures are provided by most suppliers of welding consumables to asssure minimum heat input to avoid the formation of harmful intermetallic compounds.

Here is a web site you might find interesting regarding the determination of recommended preheat temperatures;

http://homepage3.nifty.com/yurioka/exp.html

 

[SJones]

Welding Journal, April 2007, pages 104-107

Interpass temperature can be governed both by standards and the need to control microstructure by the total amount of heat transferred to the weld zone and parent material that affects the resultant cooling rates.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdoweb/

 

[SJones]

http://www.eng-tips.com/viewthread.cfm?qid=182830

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdoweb/