Normally, the hardenability and weldability of advanced high strength steels (AHSS) are expressed in terms of carbon equivalent (CE). I tried to calculate the carbon equivalent of TWIP steel (900 MPa) with different CE definitions and the values obtained was,
CE=3.5 (IIW formula)
CE= 1.4 (Ito-Basseyo formula)
CE= 0.7 (Blondeau model)
But, these values are quite high compared to that of other AHSS. So, I doubt whether the carbon equivalent can be used to express the hardenability or weldability of TWIP steels. Could anyone please give some suggestions?
First of all CE is just an empirical concept to have an rough idea about hardenability and/weldability. Different formulation of CE was developed to cater different aspect of the steel; e.g. IIW is not applicable for AHSS or HSLA steel; some CE is only applicable for spot weld, some CE incorporates UTS of the steel etc. The fact is AHSS is not a difficult steel to weld, so by "convention" a low CE would be expected for AHSS.
Dear Dr. Chandra Bhanu Basak,
Thank you for your valuable comments.
As you mentioned, the CE values of AHSS are normally low, except that of TWIP steel. In that case, CE value of TWIP steel really represents the hardenability or weldability?
Regards
CE formula which ever you are using, that will be applicable for certain range of composition of steels. If your TWIP steel chemistry lies within that range I think there should not be any harm in considering this for predicting weldability.
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