To heat treat DSC® Inox, harden it at 1922-1976°F (1050-1080°C) for 15-20 minutes in a vacuum or under protective gas, quench it in air, deep freeze it right away, and temper it twice for 45 minutes at 356-374°F (180-190°C). That gives 60-61 HRC for a knife blade. If you forged the billet, soft anneal it before machining. Every step below follows BALBACHDAMAST®'s datasheet for DSC® Inox.
What you're heat treating
DSC® Inox is two stainless steels, 1.4034 and 19C27, forge-welded in 120 layers by BALBACHDAMAST® in Laubuseschbach, Germany. The 1.4034 etches dark and the 19C27 stays bright. Heat treat it as one material: as the mill puts it, Damascus is a new material with its own hardness profile, so follow the schedule written for the pair, not the numbers for either steel on its own.
Billets arrive soft annealed at 22-27 HRC. Finish profiling, grinding and drilling in that state; the welded layers won't separate under machining.
Step 1: Forging (only if you forge)
Forge DSC® Inox between 1742°F and 1922°F (950-1050°C), and don't go above the upper limit. The steel stays very tough even at forging heat, so BALBACHDAMAST® recommends forging by hand only for smaller dimensions. Cool it slowly after shaping. Cold working usually isn't possible, so shape it hot or by grinding.
Step 2: Soft annealing after forging
If you forged the billet, soft anneal it before any machining:
Heat it to 1526°F (830°C).
Hold it at 1526°F for at least 4 hours.
Cool it slowly in the furnace.
Take it out below 752°F (400°C).
If you're working straight from the delivered billet, skip this step: it arrives soft annealed.
Step 3: Hardening
BALBACHDAMAST® recommends hardening DSC® Inox in a vacuum or under protective gas, which keeps the surface from oxidizing in the furnace. Hardening matters for more than hardness: stainless Damascus reaches its full corrosion resistance only once it's hardened. If you don't have a vacuum or protective-gas furnace, a commercial heat treater with one can do this step for you.
Heat to 1922-1976°F (1050-1080°C).
Hold for 15-20 minutes at that temperature.
Quench rapidly in air.
Deep freeze right away (step 4).
Step 4: Deep freezing
Deep freezing isn't required, but BALBACHDAMAST® recommends it, and its hardening steps put it right after the air quench, before the first temper. You can repeat the deep freeze between the two tempers.
Step 5: Tempering
Temper at least twice. BALBACHDAMAST®'s two schedules:
Knife blades: 2 × 45 minutes at 356-374°F (180-190°C), for 60-61 HRC.
Decorative items: 2 hours at 572°F (300°C), for 56-57 HRC.
Let the piece cool to room temperature between tempers. The lower temper keeps the hardness a working edge needs; the higher one trades hardness for toughness, which suits jewelry and decorative pieces.
Step 6: Check the result
After tempering, check the hardness with a file or a hardness tester: a file should skate off a hardened edge. DSC® Inox moves very little in heat treatment, and BALBACHDAMAST® lists low distortion among its characteristics.
Step 7: Etching
Etch the finished, hardened piece:
Fine polish it, up to a mirror polish.
Degrease it with dish soap or acetone.
Etch in fresh sulfuric acid (H₂SO₄, 15-20%) heated to 122-140°F (50-60°C) in a water bath. Each 5 minutes etches about 5 µm deep; BALBACHDAMAST® recommends about 20 minutes, for about 20 µm.
Neutralize it thoroughly.
Polish or sand it lightly again, above 2500 grit, until the contrast is where you want it.
Don't use ferric chloride on DSC® Inox: BALBACHDAMAST® lists only sulfuric acid for it. Follow the safety instructions for handling acid. The full process is in How to Etch Damascus Steel.
The short version
Forge at 1742-1922°F and cool slowly. Soft anneal after forging: 1526°F for at least 4 hours, furnace cool, take it out below 752°F. Harden at 1922-1976°F for 15-20 minutes in a vacuum or under protective gas, quench in air and deep freeze. Temper twice for 45 minutes at 356-374°F for 60-61 HRC, or 2 hours at 572°F for 56-57 HRC on decorative pieces.
DSC® Inox is in the size finder, cut to the inch you order. Orders placed before 2 pm Pacific ship the same business day from Ashland, Oregon. For what DSC® Inox is and where it shines, see the DSC® Inox guide; for carbon, see the carbon heat treatment guide.