If the preheat is reduced substantially, then distortion will increase and cooling rate will increase also substantially. If cooling rate to high, especially during first pass, then lack of fusion is more probable in large thickness. In some bainitic steel grades rapid cooling rate could lead to martensite formation.
If interpass temperature will increase substantially then the heat input will increase substantially which could lead to grain growth etc.
The logic behind is that in case of large changes the metallurgy has to be reconsidered
2016-11-13 6:11 GMT+02:00 Kannayeram Gnanapandithan <kgpandithan@gmail.com>:
--ASME SECTION IX, QW 406-Preheat
QW 406.1, Preheat temp should not decrease more than 100*F(55*C) and QW 406.3, Inter pass temp should not increase more than 100*F ( 55*C). What is the logic to choose temp limit 100*F( 55*) and consequences if exceed this limitations
THANKS & BEST REGARDS,KG.PANDITHAN, IWE, AWS-CWI, CSWIP 3.1,CONSULTANT-WELDING & QUALITYMobile no: +919940739349
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Dr. Georgios Dilintas,
Dipl. Ing. In Aeronautic and Space Engineering
Ph.D in Mechanics of Solids - Computational Mechanics
A.I.S, A.N.I, IRCA Lead Auditor
Welding, Stress Analysis, Corrosion, QA/QC, Failure Analysis, Risk Analysis
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