Acceptable content for an unspecified element ladle analisys
Acceptable content for an unspecified element ladle analisys
(OP)
Hi all,
I'm dealing with a standard CrMoV steel where the Nb maximum acceptable ladle value is not specified. I think in this case I should consider it as residual element, tough I don't have any clue of where is the limit between residual and intentionally added. There might be an international standard such as ASTM or ASME, which clearly defines this limit for this steel family, but I couldn't find anything in this regard. Does any of you know standards that could answer my doubt?
Thanks a lot for your help.
I'm dealing with a standard CrMoV steel where the Nb maximum acceptable ladle value is not specified. I think in this case I should consider it as residual element, tough I don't have any clue of where is the limit between residual and intentionally added. There might be an international standard such as ASTM or ASME, which clearly defines this limit for this steel family, but I couldn't find anything in this regard. Does any of you know standards that could answer my doubt?
Thanks a lot for your help.





RE: Acceptable content for an unspecified element ladle analisys
Maui
RE: Acceptable content for an unspecified element ladle analisys
Maui
RE: Acceptable content for an unspecified element ladle analisys
Nb is a key constituent of some high strength/low alloy steels. It could be useful or detrimental depending on your alloy and the use to which you intend to put it.
RE: Acceptable content for an unspecified element ladle analisys
C=0,30%
Cr=1%
Mo=1%
V=0.30%
On the heats the Nb content which is not specified by applicable spec. scatters from low values of 0.002 up to values of 0.02. While I feel that the low values could well be considered as residual impurity from scrap, I do not have the same concern on the higher ones. Therefore I was trying to figure out whether there would be international codes and/or standards that limit the unspecified elements to typical residual maximum contents. Regardless the possible harmful effect that such a Nb content would have on the steel properties, which I don’t think is an issue for this steel grade, setting such a limit by means of a code/standard would then help me a lot through the worthy discussion with the steel mill.
Have a good day
RE: Acceptable content for an unspecified element ladle analisys
RE: Acceptable content for an unspecified element ladle analisys
Nb has been used as a microalloy for decades in carbon and low alloy steels as a grain refiner and strengthener in additions as low as 0.015% (aim) and is often used together with Vanadium. It combines with carbon and nitrogen to form fine niobium carbo-nitrides when used in your high temperature alloy and will provide real increases in creep properties at the 0.02% level.
Nb is also used in low temp. steels. It essentially permits the lowering of carbon content yet maintaining high strength.