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Re: [MW:12974] RE: 12956] Cracking problem during Hardfacing (FCAW)

By Materials & Welding
Hi Ajay
 
Any hardfacing deposit with hardness more than @ 52 HRC is bound to show cracks. They are called as Stress relief cracks and are mandatory after hardfacing. You cannot avoid them.
As you are depositing Tungsten carbide the hardness will be definately more than 63 HRC.
You have not mentioned the thickness of hardfacing deposit you are welding. As per my past experience Tungsten carbide can be deposited only upto max. 1 layer @3mm. Else the deposit becomes too brittle and chunks out.
You have not mentioned your final hardness requirement.
As per that you can give a barrier layer of E309L.
If your application needs a crack free deposit then you have to go for Thermal Arc Spray or PTA process.
 
Regards
 
Prem S Nautiyal

Mobile     +91 9004063879 / 9769316004



--- On Mon, 11/14/11, pgoswami <pgoswami@quickclic.net> wrote:

From: pgoswami <pgoswami@quickclic.net>
Subject: [MW:12966] RE: 12956] Cracking problem during Hardfacing (FCAW)
To: materials-welding@googlegroups.com
Date: Monday, November 14, 2011, 8:47 AM

Hi Ajay,
 
Deposition of tungsten carbide is very hard with little or no ductility. It's advisable  to know what's is the matrix (microstructure) and preferably the chemical composition of the deposit.
 
If a hard alloy in the form of hard facing  is deposited by arc welding process then it may crack on shrinkage ,if the there's not enough ductility to accommodate the shrinkage stress/es.
 
If the deposit required is more than one layer ,use of a barrier layer of austenitic alloy ( E=ER-309 or Inconel 82(ER-NiCr-3) or Inconel 182 (E-NiCrFe-3) could be useful.
 
You may check  with the consumable manufacturer with the problem and see what's their response. More feedback of your end on this subject would be appreciated.
 
The following AWS article provides good information on effects of various alloying elements on hardfacing deposits/microstructures.
 
Thanks.
 
 
Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist & Consultant
Ontario,Canada.
Email-pgoswami@sympatico.ca,
 
  1. http://www.aws.org/wj/supplement/wj0710-133.pdf
 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of ajay pawse
Sent: Saturday, November 12, 2011 10:15 PM
To: materials-welding@googlegroups.com
Subject: [MW:12956] Cracking problem during Hardfacing (FCAW)

Hello Friends,
 
We are conducting trials for Tungsten carbide Hardfacing on F-22 material (2.1/4Cr - 1 Mo). we are facing problem of transverse hairline cracks on weldbead. need your help to overcome this problem.
Process: FCAW
Filler wire Dia: 1.2mm
Cuerrent used: during trial we changed current from 87Amps to 140Amps. different runs were taken but all cracked
Volts: 16 to 19.5V
Wire feed: 2.8 to 5m/min
Travel speed: 235 to 600mm/min
Preheat: 120 to 260DegC
Shielding: Argon
 
With these parameters, we achieved satisfactory weld bead appearance though.
 
Please let me know if i am missing any factor which is vital for the success of the process. also need you guidance on the parameters i tried.Hope to see your suggestions soon
 
Please let me know if anyother info is needed.
 
Thank you.
 
Regards,
Ajay
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