Dear John,
Sorry, but, I like to correct you at two places, where you mentioned 0.8% carbon for 304, actually it is 0.08% and not 0.8%. I think it is typographical error only.
Also to prevent carbide precipitation during welding, there are two more menthods: one to use stabilised grade of electrode and second to solution anneal after welding.
Kind regards,
Nikhil Parikh
On Mon, 13 Jul 2009 19:55:50 +0530 wrote
>Hamed,
>
>304 is the general designation of a group of alloys all having nominally
>18% Cr and 8% Ni and no other metallic elements added. 304 can have any
>carbon content up to a maximum of 0.8% C.
>
>304 has several variations depending on carbon content and nitrogen
>addition.
>
> The low carbon variations are preferred for water wetted
>service. Stress corrosion cracking, knife line attack, etc are
>controlled by preventing precipitation of Cr carbides (removing carbide
>from solid solution in the within the grains). Precipation of Cr
>carbides is achieved by limiting the amount of carbon available to form
>them. Room temperature strength is generally decreased. The low carbon
>varieties have poor elevated temperature (creep strength) and are
>prohibite for use at elevated temperatures by ASME Code. Nitrogen may
>be added to enhance strength of the low carbon variations at room
>temperature and at cryogenic temperatures.
>
> *
> 304L - nominally 18%Cr - 8% Ni, carbon < 0.03%
> *
> 304LN - nominally 18%Cr - 8% Ni, carbon <0.03% and
>0.010% < N < 0.16%
>
> The high carbon variaion has elevated carbon content is intended
>for high temperature service (creep service). Examples would be
>superheater tubes in fossil fueled boiler.
>
> *
> 304H - nominally 18% Cr - 8% Ni, 0.04% < carbon < 0.10%
>
>There is also an 304N variation that has the same general chemistry as
>304, including carbon < 0.8%, but with the addition of 0.010% < Nitrogen
>< 0.016%
>
>Note that it is now common practice for most 304 to be produced with low
>carbon content and to be dual certified, i.e. 304/304L. If you are
>going to use 304 at elevated temperatures you need to evaluate the
>chemistry carefully or specify 304H.
>
>Hope this helps.
>
>John
>
>________________________________
>
>From: materials-welding@googlegroups.com
>[mailto:materials-welding@googlegroups.com] On Behalf Of Hamed
>Sent: Sunday, July 12, 2009 7:50 AM
>To: materials-welding@googlegroups.com
>Subject: [MW:2659] 304 & 304 L
>
>
>
>Dear all
>
>I want to know the difference between SS 304 & 304 L?
>
>
>
>RGARDS
>
>
>
>
>
>>
>
Sorry, but, I like to correct you at two places, where you mentioned 0.8% carbon for 304, actually it is 0.08% and not 0.8%. I think it is typographical error only.
Also to prevent carbide precipitation during welding, there are two more menthods: one to use stabilised grade of electrode and second to solution anneal after welding.
Kind regards,
Nikhil Parikh
On Mon, 13 Jul 2009 19:55:50 +0530 wrote
>Hamed,
>
>304 is the general designation of a group of alloys all having nominally
>18% Cr and 8% Ni and no other metallic elements added. 304 can have any
>carbon content up to a maximum of 0.8% C.
>
>304 has several variations depending on carbon content and nitrogen
>addition.
>
> The low carbon variations are preferred for water wetted
>service. Stress corrosion cracking, knife line attack, etc are
>controlled by preventing precipitation of Cr carbides (removing carbide
>from solid solution in the within the grains). Precipation of Cr
>carbides is achieved by limiting the amount of carbon available to form
>them. Room temperature strength is generally decreased. The low carbon
>varieties have poor elevated temperature (creep strength) and are
>prohibite for use at elevated temperatures by ASME Code. Nitrogen may
>be added to enhance strength of the low carbon variations at room
>temperature and at cryogenic temperatures.
>
> *
> 304L - nominally 18%Cr - 8% Ni, carbon < 0.03%
> *
> 304LN - nominally 18%Cr - 8% Ni, carbon <0.03% and
>0.010% < N < 0.16%
>
> The high carbon variaion has elevated carbon content is intended
>for high temperature service (creep service). Examples would be
>superheater tubes in fossil fueled boiler.
>
> *
> 304H - nominally 18% Cr - 8% Ni, 0.04% < carbon < 0.10%
>
>There is also an 304N variation that has the same general chemistry as
>304, including carbon < 0.8%, but with the addition of 0.010% < Nitrogen
>< 0.016%
>
>Note that it is now common practice for most 304 to be produced with low
>carbon content and to be dual certified, i.e. 304/304L. If you are
>going to use 304 at elevated temperatures you need to evaluate the
>chemistry carefully or specify 304H.
>
>Hope this helps.
>
>John
>
>________________________________
>
>From: materials-welding@googlegroups.com
>[mailto:materials-welding@googlegroups.com] On Behalf Of Hamed
>Sent: Sunday, July 12, 2009 7:50 AM
>To: materials-welding@googlegroups.com
>Subject: [MW:2659] 304 & 304 L
>
>
>
>Dear all
>
>I want to know the difference between SS 304 & 304 L?
>
>
>
>RGARDS
>
>
>
>
>
>>
>
 |
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