Ferritic stainless is the chromium-only family, with 16-18% chromium, no nickel and carbon held at or below 0.08% in the carrier’s table. It is magnetic, does not harden by quenching, and suits kitchen equipment and water tanks. It saves the nickel supply, but it does not relax the carbon limit, so it still needs low-carbon scrap or a low-carbon chromium source.
Part of Stainless Steel Production
The chromium-only stainless family: composition, how to make it, how to recognise it, and what it is good for.
No Nickel, Same Carbon Limit
The carrier lists ferritic stainless (430 type) at 16-18% chromium, 0% nickel, 0.08% carbon maximum, magnetic, with good corrosion resistance, used for kitchen equipment and water tanks. The advanced-materials page gives a wider 12-17% chromium range for ferritic; the 16-18% figure from the carrier is used here because it is the one tied to a stated carbon limit.
The attraction is that no nickel is needed (Nickel Sources). The cost, as Carbon Control shows, is that the chromium must still come with very little carbon. A carbon-rich ferrochrome fails here the same way it fails for austenitic.
What You Need
- Low-carbon base steel or salvaged ferritic scrap.
- Ferrochrome (Ferrochrome Production) if building from ore.
- The furnace and sequence of Melting and Alloying.
Method: Making And Using A Ferritic Heat
Step 1: Calculate the charge. For 100 kg at 16% chromium from 65% ferrochrome: 16 / 0.65 = 24.6 kg. At 18%: 18 / 0.65 = 27.7 kg. The rest is base steel, before any allowance for chromium lost to slag.
Step 2: Melt, blow, skim, add ferrochrome, trim as in Alloy Addition Sequence.
Step 3: Cast or forge. Hot forging is at 1,100-1,250 °C and not below 900 °C (Hot Forging). Casting is covered by Investment Casting.
Step 4: Finish. Descale, passivate (Passivation Treatment) and polish (Surface Finishing).
How To Recognise It In Scrap
It is attracted by a magnet and, unlike a martensitic knife, a file bites it. Together those two tests separate ferritic from austenitic (non-magnetic) and from hardened martensitic (file skates). The tests are in Metal Identification. Weakly magnetic pieces exist in the austenitic family, so test several pieces.
What It Does Not Do
- It does not harden by quenching. The carrier makes martensitic the hardenable family (Martensitic).
- It is not the best in harsh service. The carrier ranks austenitic as best for corrosion resistance.
- Welding and heat exposure can embrittle it, as I recall; treat it gently and see Welding Stainless. The mechanisms belong to the materials-science treatment.
Common Mistakes
- Assuming “no nickel” means “easy”. The carbon limit is identical to austenitic’s in the carrier’s table.
- Quench-hardening a ferritic part and expecting a hard edge. It will not harden.
Safety
Melting and forging hot steel
Molten-steel safety is in Melting and Alloying; forging temperature work is in Hot Forging. Both involve metal at over 1,000 °C and fume from chromium-bearing steel.
What’s Next
- Learn next: Austenitic (300 Series) - adding nickel for the best corrosion resistance
- Combine with: Hot Forging - shaping the finished alloy