Dear Sandeep, When you use smaller dia electrodes it will decrease heat input for sure. But the total heat input is what matters. If you use higher dia lesser number of pass is required. So we cannot confirm unless you tested with both big and small dia electrodes to verify toughness values.
Thanks & Regards
Abin Eldhose
QC Inspector
DAEWOO E&C RRE EPC-4 PROJECT TEAM Tel: +971-56-7103039
--- On Sat, 16/7/11, sudhakar kuppuswamy <mechsudhakar@gmail.com> wrote:
From: sudhakar kuppuswamy <mechsudhakar@gmail.com>
Subject: Re: [MW:11769] Impact value in HAZ
To: materials-welding@googlegroups.com
Date: Saturday, 16 July, 2011, 11:15 PM
To achieve better HAZ impact property you can weld with temper bead technique, where the HAZ is subjected to less heating during welding when compared normal technique.
Preheat the base material to about 100 C (if the carbon content is high go for higher degree of preheat), this will reduce the rate of cooling so you can avoid martensite formation (which is a hard structure) and end up with pearlite( fine grain structure, which has good impact property)
If Ur welding thick sections, doing PWHT will helps to achieve good HAZ impact properties
By using smaller dia filler wire you can use lesser current which inturn reduce Heat input, (heat input is the function of current, voltage ,travel speed) but the rate of cooling will be high (high cooling rate is not advice able), this can be controlled by doing preheating. If you do post heating (immediately after welding) for few minutes (say 30 min) ,cooling rate will be very slow and you will get fine microstructure like pearlite or bainite instead of martensite .
On Sat, Jul 16, 2011 at 4:43 PM, yusufkhan pathan <yusufkhanp97@gmail.com> wrote: Dear sandeep, However as mentioned by Dinesh, voltage, current & travel speed as the important factors afftecting the heat input. as per my past experience related to SMAW we used to control these factors by increasing the travel speed thereby resulting in good impact values. I am not sure about GMAW, whether this method can be applicable. Another factor which effects the energy value is the choice of consumables. Yusufkhan. M. Pathan Engineer-Quality Air Liquide Engg (IND) Pvt.Ltd. Email to : yusufkhan.pathan@airliquide.com Cell:(+91) 8008804165
Dear All
How we can get better impact values in HAZ with GMAW process in non
alloyed carbon steel?
like with multi pass welding.
Please provide your valuable ideas.
Regards
Sandeep Kumar
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With regards,
Sudhakar.k
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