Hard facing deposits which contain carbides display cracks that are really stress relief checks as mentioned.
These cracks will go only to the depth of hardfacing & will not propogate to base metal & are harmless.
Only thing to be ensured that the crack is transverse and not longitudinal & base metal has not cracked.
J.Srinivasan
Sent from BlackBerry® on Airtel
From: Ramin Kondori <raminkondori@gmail.com>
Sender: materials-welding@googlegroups.com
Date: Sat, 22 Jun 2013 08:57:41 +0430
To: <materials-welding@googlegroups.com>
ReplyTo: materials-welding@googlegroups.com
Subject: Re: [MW:18000] Cracks on Hard Facing Overlay
Dear Sevak:
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Check-cracking, or checking as it's sometimes called, occurs in the metal carbide families and can be seen as cracks that are perpendicular to the bead length. They generally occur from 3/8 to 2 inches apart and are the result of high residual stresses of hard-facing weld metal as it cools. Other alloys such as the austenitic and martensitic families, don't crack when applied with proper welding procedures but for many of chromium carbide alloys, check-cracks appear when cooled to moderate temperatures; this is normal.
Again, be careful if you try to stop this cracks, the residual stress will build-up and whatever you do, it will eventually crack, this time it will be a wide long crack that tears your work-piece apart...!!!
Check cracks propagate through the thickness of the weld bead and stop at the parent metal, as long as it's not brittle (like your case). In cases in which the parent metal is hard or brittle, you should select a buffer layer of a softer, tougher weld metal. Like what Mr. Swamy recommended, Ni-base or austenitic buffer family are good choices for a buffer deposit.
Regards
On Sat, Jun 22, 2013 at 8:25 AM, pgoswami <pgoswami@quickclic.net> wrote:
Hello Hiren,Hard facing alloys usually have little or low ductility as compared to many other corrosion or erosion resistant alloys. However cracks are not accepted as a rule. Hard facing containing cracks could be dislodged in service, if the extent of cracking is severe.Perhaps adjusting the composition would be the way to go. The other technique could be use of austenitic(Ni based ) barrier layer.What' re the technical requirements ?? You refer this article for general guidance.Thanks.Pradip Goswami, P.Eng,IWEWelding & Metallurgical SpecialistOntario, Canadahttp://www.twi.co.uk/news-events/bulletin/archive/pre-1998-articles/1991-articles/cracking-of-hardfacing-alloys-prevent-cure-or-ignore/
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of cbe swamy
Sent: Friday, June 21, 2013 1:30 AM
To: materials-welding@googlegroups.com
Subject: RE: [MW:17993] Cracks on Hard Facing OverlayDear All,
Where direct fusion welding is not appropriate, as in the case of an extremely hot-crack-sensitive casting, other
approaches might prove useful. One option is to "
Date: Fri, 21 Jun 2013 09:49:43 +0530
Subject: [MW:17992] Cracks on Hard Facing Overlay
From: hirensevak80@gmail.com
To: materials-welding@googlegroups.comDear Experts,One of the manufacturer is using XL-CCH electrodes for Hard Facing Weld Overlay on c arbon steel material. (Chromium Carbide Alloy Deposit Hard Facing Electrode).The weld overlay outer surface is showing parallel hair line cracks.The manufacturer is arguing that these cracks are bound to develope due to inherrent properties of electrode & it is good to observe cracks on weld for ensuring the application of these type of electrode. The electrode catalogue also states that cracks can be developed on weld surface.My question is which code/standard allow cracks on such hard facing overlay ?
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