Please disregard anything anyone tells you about steel if they are completely ignorant about what steel is. By definition ALL steel contains Fe (iron) with carbon, that's what steel is. High carbon, low carbon, alloy, stainless. Hardenability depends on carbon.
Low carbon steel (mild steel) contains between 0.05% to 0.25% carbon. High carbon steels contain 0.30% to 2.00% carbon. Above that and you have cast iron.
"Alloy steels" have various other stuff mixed in generally to enhance certain properties such as tensile strength. "Stainless steels" are a class of alloy steels that contain a minimum of 11% chromium, it still contains carbon
4140 Chrome Moly:
C | Cr | Mn | Si | Mo | S | P | Fe |
0.38-.43% | 0.80-1.10% | 0.75-1.0% | 0.15-0.30% | 0.15-0.25% | 0.040% max | 0.035% max | Balance |
316 Stainless:
| | Carbon | Silicon | Manganese | Phosphorus | Sulphur | Nickel | Chromium | Molybdenum | Nitrogen |
316 | Specification (max) | 0.08 | 0.75 | 2.00 | 0.045 | 0.030 | 10.00 – 14.00 | 16.00 – 18.00 | 2.00 – 3.00 | 0.10 |
Without knowing the particulars, I would be cautious about using CLR as it is probably (my guess only) aqueous based and as such a corrosion risk. Even "stainless" steels are vulnerable to corrosion.