Heat input is used for a couple of reasons. In general it is required when there is a reason to limit the maximum heat input to control cooling rates and or grain size in conjunction with notch toughness. It can also be required when welding quenched and tempered steels to minimize the extent or limits of the heat affected zone to minimize the degradation of the mechanical properties in the affected areas.

You may have an occasion when there is a lower limit for the heat input, but that isn't the normal situation. It is required when qualifying a WPS that will be employed in a bridge and you are working to AWS D1.5. It provides the engineer and the welder a means of bracketing the acceptable ranges for the welding variables based on the parameters recorded on the procedure qualification record.

You need to read the applicable welding standard closely to see what is required. The formulas you listed are generally the ones used by many welding standards.

Best regards - Al

Hi magesh

I suspect that there is a question behind the question here. While the typical equation for calculating the heat input is simple enough, there is much debate in some circles, as to how to actually calculate the heat input ranges qualified according to code. I will give you my take on this, but you will probably get a lot of different opinions here.

The basic calculation for heat input is: (Amps x Volts) / Travel speed (The 60 and 1000 is to just sort out the units.)

To calculate the heat input while performing the PQR tests, I calculate the heat input for each run based on the average values of amps, volts and travel speed. This gives me a range of heat input values, based on the average values per run.

On the WPS, I give the ranges of Amps, Volts and Travel speeds based on the typical or code ranges around the values I calculated above. I also state the heat input ranges based on the code ranges. If you took the "Max Amps x Max Volts / Min travel speed" it will probably give you a value higher than the Max heat input allowed on the WPS, so some people reject this saying that these do not tie up, but the issue is that generally you will not be welding at the limits of all the values simultaneously, and if you do, then obviously it would not meet the WPS heat input range, so there is no contradiction. (To my mind.) Normally when the amps increase, then the travel speed also increases, so normally when welding at the max energy values you will be welding at the maximum travel speed which then brings the heat input back in line.

Hope this is what you were looking for.

Regards
Niekie

magesh

Number 1 is the correct answer to your question.

Hi Al,

Noted and Thanks