I wish I had some useful input but I'm just as curious to see if there is a formula or rule of thumb exists for this problem. similar to machining the majority of heat will go in the removed material leaving the base material relatively cool, secondly travel speed is quite high which confrims the fact that plasma cutters have quiet a small HAZ. So I would imagine the heat input is quite low. However just like a laser there still a haz which can lead to metallurgical issues
Hello Chet, I believe all of this is still based on time at temperature and the variables that could be included here might make for a sizeable margin of error. I believe you might need to take cutting gases into consideration in this equation as well since there could be some considerable differences when comparing nitrogen, shop air, argon, and any of the other associated cutting or cooling gases. Even the selection of amp settings, nozzle diameter choices, and cutting gas pressures could have a great effect. Quite obviously, travel speeds are likely to be across the board depending upon the experience and proficiency of a particular operator and or his/her particular style or understanding of the process and what constitutes a "good" or "efficient" cut. I am making some of my statements on this topic based on a comparison to GTAW welding. You can make welds with the GTAW process based on a higher amperage level and a faster travel speed and achieve appropriate penetration/fusion or you can opt to run with a slower travel speed due to a possible lack of confidence or tentativeness and end up inputting a greater amount of heat along the weld path. If you choose the latter choice you will certainly have a greater HAZ area due to the longer time at temperature variable. I will be interested to see some of the responses to your inquiry.
Also Chet, is there a specific reason for the need of this information? Is there a concern with hardening or other types of metallurgical issues? If so, couldn't you use a form of hardness testing leading up to the edge of the cut in order to determine the affected zone? Just curious. Best regards, Allan