Weldability of Steel
Weldability of Steel
(OP)
Hello Forum,
Anyone aware of a scale comparing weldability of steel to carbon content? I am specifically attempting to compare ASTM A27 70-40 (%C = .25) to ASTM A148 90-60 (%C = TBD)
Gracias
Anyone aware of a scale comparing weldability of steel to carbon content? I am specifically attempting to compare ASTM A27 70-40 (%C = .25) to ASTM A148 90-60 (%C = TBD)
Gracias





RE: Weldability of Steel
C.E. = C% + Mn%/6 + (Cr%+Mo%+V%)/5 + (Ni%+Cu%)/15
You also must take into account the Mn and Cr content, as Mn should be limited if C is above .25%, but Mn can be increased slightly if C is below .25%. At our site we also adjust Cr but that is not in ASTM A27 spec. A148 is more focused on mechanical properties with chemistries set by the caster and/or purchaser.
Section size can also be a factor. With larger sizes you may want to restrict CE, especially if the chemistry is off grade.
Jominy hardenability can also be compared at the J4, J8, and J12 positions using SAE J406.
RE: Weldability of Steel
I've seen the carbon equivalent formula (which puts A27 at %C = .583) and I know this material is very good for welding, however that is where my knowledge ends as far as relating %C to weldability.
RE: Weldability of Steel
RE: Weldability of Steel
RE: Weldability of Steel
RE: Weldability of Steel
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RE: Weldability of Steel
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Thanks for all the replies!
RE: Weldability of Steel
As always your erudite posts on this site help clear many basics. I just had a few queries/ concepts to be cleared.
1. As a thumb of rule, does a low %C in steel equate to better weldability than a steel with a higher %C content?
2. As a thumb of rule, does a higher CE in steel equate to lower probability of the steel cracking post welding?
Thks in advance.
-jehan
RE: Weldability of Steel
Given that all other variables in this comparison are equal between steels, yes. Carbon has the greatest influence on strength level in iron-base alloys - the higher the carbon content the higher the strength. With that, higher carbon means that more caution is required for welding to achieve similar results (sufficient ductility and avoidance of delayed cracking). CE should be used to determine the application of preheat and post weld heat treatment requirements. This is really the value of CE use for welding.
I believe what you have meant to state was lower CE, not higher? If lower CE, the answer is yes. The reason is that if a harmful (fresh martensite) microstructure forms as a result of thermal gradients during welding, the hardness of this harmful microstructure will be lower in magnitude in comparison to the harmful microstructure formed in higher carbon steels, and will not be as prone to delayed cracking.
RE: Weldability of Steel
Just one non-relevant comment, I do not think Cr and Mo should share same coefficient because I think most people know that Mo is considered much more powerful hardenability agent than Cr, and therefore more expensive.
RE: Weldability of Steel
thanks for clearing my concept and yes I did mean "lower CE" and not "higher CE".
-jehan
RE: Weldability of Steel
The current IIW and AWS formula for CE includes the Si%/6, the orignal formula presented by Deardon and O'Neill did not include it.
Dik