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Re: [MW:24405] RE: 24355] Impact Test & cooling Rate-Preheating (carbon steel)

By Materials & Welding
in welding, lower thickness will have slow cooling  when compared to higher thickness weld which will have fast cooling rate, that is why to slowdown , preheat is applied to avoid hard structure which inferior for toughness properties

THANKS & BEST REGARDS,
KG.PANDITHAN, IWE,  AWS-CWI, CSWIP 3.1,
CONSULTANT-WELDING & QUALITY

On Sat, Feb 27, 2016 at 10:21 PM, 'Shashank Vagal' via Materials & Welding <materials-welding@googlegroups.com> wrote:
One more addition to Alan's good comment:
In case of lower thicknesses, the cooling rate tends to increase and may lead to martensite formation. But it is not so slow and sustained a cooling rate as to promote grain growth/reduced ductility, as you are allowed to weld between preheat & interpass temperatures.
 
BR,
Shashank C Vagal 



From: Alan Denney <alan@denney1.freeserve.co.uk>
To: materials-welding@googlegroups.com
Sent: Tuesday, 23 February 2016 2:59 AM
Subject: [MW:24358] RE: 24355] Impact Test & cooling Rate-Preheating (carbon steel)

 
Alan Denney
AKD Materials Consulting Ltd
 
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Mohd Siraj
Sent: 22 February 2016 09:22
To: Materials & Welding <materials-welding@googlegroups.com>
Subject: [MW:24355] Impact Test & cooling Rate-Preheating (carbon steel)
 
Dear all,
 
Background: 
impact testing is more critical for less(low)thickness than higher thickness.
 
Reason  : 
fine grain form during fast cooling and course grain form during slow cooling.
 
Question is:
Preheating use to lower the cooling rate for higher thickness.
So lower the cooling rate means form the course grain,course grain lower the toughness.
 
Preheating contributing to lower the toughness?
 
 
 
 
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