Working With Boron-Alloyed Steel – Removal (Plasma Arc Cutting)

A plasma arc cutter is a great tool for making initial cuts.
A plasma arc cutter is a great tool for making initial cuts.

With so much boron-allowed steel, does a plasma arc cutter even belong in a modern collision repair facility? The simple answer is yes but in limited areas, and it should be used at the lowest setting that can still effectively cut the material.

When a plasma arc cutter is used, the panel being cut does not absorb much of the heat outside of the immediate cutting area as long as it is being cut all the way through. However, any panels that are behind the panel being cut absorb a great amount of heat, which can reach over 650ºC (1,200ºF) in a matter of seconds. As a best practice, a plasma arc cutter should not be used to remove exterior panel spot welds if ultra-high-strength steel (UHSS) reinforcements are present. The heat from the cutting arc will be directed into the panels behind which will destroy the UHSS.

A plasma arc cutter can be effectively used to initially cut large damaged assemblies, or it can be used to make the initial cut on an assembly that will be sectioned. As a best practice, when making an initial cut with a plasma arc cutter, scribe the final cut line on the part and set up a guide so that the plasma arc cut line is about 3 mm (1/8") away from than the final cut. This is done to allow for the rough edges of the initial cut made with the plasma arc cutter to be ground down to the straight final cut line. This will also limit the heat affect zone (HAZ) even further. The HAZ from the plasma arc cutter is fairly low if done correctly. The heat that is generated around the cut line is about 205–260ºC (400–500ºF) when the part is being cut all the way through.

Additional information about plasma arc cutting can be found in the I-CAR Best Practices for High-Strength Steel (SPS09) course.


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