Debasis The concept of Carbon Equivalent was developed in an effort to reduce to a single number the influence of the contribution of the various alloying elements on the difficulties encountered in welding-alloy-steel, therefore making the problem more tractable. One of the accepted empiric formulas equates the carbon equivalent to the sum of the percentage of each element divided by a certain factor as follows: Carbon Equivalent CE = %C + %Mn/6 + %Ni/15 + %Cr/5 + %Mo/4 + %V/5. The usage of this formula is intended to provide a rule of thumb for deciding if and what special provisions should be implemented for welding-alloy-steel: for CE equal to or less than 0.40, no provisions are required. For CE more than 0.40 but less than 0.60 some preheating should be provided before welding. For CE more than 0.60 both pre-heating and post-heating should be applied. It is evident that this approach to weldability evaluation oversimplifies the issue and overlooks other factors, like additional elements not accounted for, thickness, restraint of the joint, nature of the filler material, thermal gradients developed, all of which contribute to and may even decide the outcome of a Welding-alloy-steel procedure. For any real application the complex of all the conditions involved should be evaluated. It is equally important to clean thoroughly all materials involved, base metal, consumables, fixtures and accessories, from grease, paint, moisture, rust, dirt and any other contaminant. Excess silicon will have adverse welding difficulties. Silicon (ferro-silicon addition in melting practices for steel making) from de-oxidizing effect (semi-killed or fully killed steel) on steel may not be effectively taken into account in the empric forumula given for CE. Trust this will help you C.V.Srinivasan Nishi Engineers Pvt Ltd India June 24, 2007 E-mail: nishi@vsnl.com >While selecting formula for Carbon Equiv. (CE) for CS MOC >with C> 0.12% the formula as it is equated does not take >into account of any effect of "Si" but it has been noted >that SI has a real effect on weldability performances. >CE = %C + %Mn/6 + (%Cr +Mo+V) /5 + (%Cu + Ni ) / 15 > >Request to have a discussion for this ignorance to Si. >regards