Dear 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 "butter" the area of the crack-sensitive casting to be joined, using a
consumable of a less crack-sensitive material. This "buttering" involves surfacing the casting locally with a consumable
before fabricating the actual weld joint. With no joint present during the buttering operation, the restraint on the
solidifying surface pass and the underlying HAZ of the casting can be quite small and defects (fusion zone and HAZ hot
cracks) may be avoided. This surfaced area can be built up slowly to a thickness where it can then be prepared as a joint
for subsequent welded attachment. Additional information on buttering can be found in the article "Hardfacing, Weld
Cladding, and Dissimilar Metal Joining" in this Volume. As another option, an insert of a less hot-crack-sensitive alloy
can be inertia or friction welded onto the mating surface of the hot-crack-sensitive casting. This insert could then be
prepared for subsequent fusion welding to the required structure. These options are contingent upon the availability of consumable materials that are acceptable in the service environment.
SFA - 5.13
A7.3.1 ENiCr-C Electrodes
A7.3.1.1 Characteristics. Undiluted weld metal of this composition exhibits a structure consisting of chromium carbides and chromium borides in a nickel-rich matrix. The nickel base and high chromium content give these deposits good heat and corrosion resistance. Care should be taken when cooling hardfacing deposits because of a tendency to stress crack. This alloy possesses excellent resistance to low stress abrasion.
SFA - 5.21
A7.1.8.2 Applications. A general purpose hard facing alloy which can be used where limited stress-relief cracks (checks) are acceptable but severe abrasion is not encountered.
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 "butter" the area of the crack-sensitive casting to be joined, using a
consumable of a less crack-sensitive material. This "buttering" involves surfacing the casting locally with a consumable
before fabricating the actual weld joint. With no joint present during the buttering operation, the restraint on the
solidifying surface pass and the underlying HAZ of the casting can be quite small and defects (fusion zone and HAZ hot
cracks) may be avoided. This surfaced area can be built up slowly to a thickness where it can then be prepared as a joint
for subsequent welded attachment. Additional information on buttering can be found in the article "Hardfacing, Weld
Cladding, and Dissimilar Metal Joining" in this Volume. As another option, an insert of a less hot-crack-sensitive alloy
can be inertia or friction welded onto the mating surface of the hot-crack-sensitive casting. This insert could then be
prepared for subsequent fusion welding to the required structure. These options are contingent upon the availability of consumable materials that are acceptable in the service environment.
SFA - 5.13
A7.3.1 ENiCr-C Electrodes
A7.3.1.1 Characteristics. Undiluted weld metal of this composition exhibits a structure consisting of chromium carbides and chromium borides in a nickel-rich matrix. The nickel base and high chromium content give these deposits good heat and corrosion resistance. Care should be taken when cooling hardfacing deposits because of a tendency to stress crack. This alloy possesses excellent resistance to low stress abrasion.
SFA - 5.21
A7.1.8.2 Applications. A general purpose hard facing alloy which can be used where limited stress-relief cracks (checks) are acceptable but severe abrasion is not encountered.
Thanks & Best Regards,
M Veera SAMY
BVQI
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.com
Dear 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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