I wanted to add a bit of experiential clarity to your question. 100-130W lasers certainly have enough power to cut mild or high carbon steel. However, you cutter needs other hardware to do this. My old employer had a Kern laser cutter. To cut steel we changed out the laser lens, used a sensor that did height following (the gap between the lens and metal was critical) and the system injected oxygen into the cut like a cutting torch. With a 150W I think the system was rated for up to 1/8" steel and could cut quite quickly. However, I never tried thicker than about 16 gauge. I also was never able to maser the setups that allowed such fast cuts. Instead I was cutting a very slow speeds, with low power. With such settings I had .007" cut widths when cutting thinner material (something like 0.8mm... sorry to me mixing units).