[MW:5859] Re: Hard-facing overlay versus Corrosion resistant overlay

Fusion hardfacing is a process by which weld materials, with superior
properties than the substrate, are applied to the substrate. Often,
two layers total 3 - 6 mm (1/4 - 1/2 in) thick are applied to reduce
the surface hardness dilution of the relatively low-cost steel
substrates in the expansive cobalt-base alloys
The most common hardfacing materials are nickel alloys and iron/
chromium alloys used in wear resistance and high stress abrasion..

Jaspal Singh, CWI-AWS, CSWIP-3.1
Assistant Manager – Welding Technology
Process Equipment Division
ISGEC, Yamuna Nagar, Haryana -135001
Phone: 911732307389
Ext: 391 Mb: +91 9996624244

On Jul 3, 8:39 am, "pgoswami" <pgosw...@quickclic.net> wrote:
> Hi Fernando,
>
> A per ASM-Metals Handbook, and AWS welding handbook  the differences between
> hardfacing and corrosion resistant overlays are as  follows:
>
> 1)      Hardfacing is the application of a hard, wear-resistant material to
> the surface of a component by welding, thermal spraying, or allied welding
> processes to reduce wear or loss of material by abrasion, impact, erosion,
> galling, and cavitation . Processes using  heat treatment or surface
> modification processes such as flame hardening, nitriding, or ion
> implantation are not considered to be hardfacing  processes. Hardfacing, as
> compared to corrosion resistant overlay normally would produce thinner
> surface coating. Hardfacing generally is based on carbide alloys. It could
> involve  application  a number of hard wear resistant carbides
> (metallurgical bonding:- through arc welding process) or application of wear
> resistant restraint  carbides (mechanical bonding:-through thermal
> spray).Nominal Hardness levels for hardfacing-typically from HRC-30-60.
>
> 2)      Corrosion Resistant Overlay or Weld Cladding :- usually denotes the
> application of a relatively thick layer (3 mm, or 1/8 in.) of weld metal for
> the purpose of providing a corrosion-resistant surface. It could be
> predominantly of austenitic type , free from any carbides (otherwise
> corrosion resistance would be  minimized. Ferrite No typically applies to
> corrosion resistant overlays. Typical hardness values for  weld
> overalys-22-35 HRC max.
>
> Essentially for Hard-facing overlay versus Corrosion resistant overlay- the
> difference  is the  service and application media. If the service media
> calls for wear resistance they the technique to be adopted is  hardfacing ,
> if for corrosion resistance then weld overlay.
>
> Valve industry needs both type of alloys depending on the service. Example
> Stellite-6 or 12 on Moderators Valves (Nuclear services)require galling
> resistances, high temperature piping require high temperature erosion
> resistance, while austenitic  alloys would be required for corrosion
> resistance in oil, gas or chemical environments. Some type of Stellite
> alloys used in the oil and gas offshore production industries would require
> both. See the attached  link to the relevant document on hardfacing alloys
> for  your  information.
>
> Hope this clarifies your query.
>
> Thanks
>
> Pradip Goswami,P.Eng.
>
> Welding & Metallurgical Engineer/Specialist
>
> Ontario Power Generation Inc.
>
> Email-pgoswami@ <mailto:sympatico.capgosw...@quickclic.net> sympatico.ca,
>
>  <mailto:pgosw...@quickclic.net> pgosw...@quickclic.net
>
> *      
>
> http://www.stellite.com/Portals/0/Microsoft%20PowerPoint%20-%20Deloro...
> lite%20Advances%20in%20Wear%20Resistant%20Alloys%20and%20Products.pdf
>
> From: materials-welding@googlegroups.com
> [mailto:materials-welding@googlegroups.com] On Behalf Of Fernando Gameiro
> Sent: Friday, July 02, 2010 4:24 AM
> To: materials-welding@googlegroups.com
> Subject: RE: [MW:5825] Hard-facing overlay versus Corrosion resistent
> overlay
>
> Thank you,
>
> Is that "thinking" well and clear defined on any code, with real figures
> like hardness or  ferrit number or what else?
>
> Regards
>
> Fernando Gameiro
>
> From: materials-welding@googlegroups.com
> [mailto:materials-welding@googlegroups.com] On Behalf Of Harish Kannepalli
> Sent: 02-Julho-2010 08:20
> To: materials-welding@googlegroups.com
> Subject: Re: [MW:5823] Hard-facing overlay versus Corrosion resistent
> overlay
>
> Dear Fernando,
>
>                      Hard facing overlay is for wear resistance
> applications, where continuous rupture of the part is involved. Incase of
> ,corrosion resistant overlays, its purely for acidic or alkali resistance
> applications. At times some overlays are hard facing as well as corrosion
> resistant.
>
>             In hard facing overlays, hardness is an important feature. In
> corrosion resistant overlays, bonding of base metal, chemistry of layers are
> some of the important features.
>
> regards,
>
> Harish.
>
> 2010/7/1 Fernando Gameiro <fgame...@velan.pt>
>
> Dear All,
>
> According to ASME IX the difference between Hard-facing overlay and
> Corrosion resistant overlay is limited to the type of tests that is required
> on PQR and WPS ?
>
> According to ASME, how to define if certain overlay is a Corrosion resistant
> or a Hard-face?
>
> Thanks
>
> Fernando Gameiro
>
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