KETOS®
(AISI O1)
Ketos is an oil-hardening tool steel which may be hardened from fairly low temperatures with little size change. This grade combines deep-hardening qualities with a fine-grained structure, affording good initial production runs, and good continued production after grinding.
Typical Chemistry
Carbon 0.90%
Manganese 1.25%
Silicon 0.30%
Chromium 0.50%
Tungsten 0.50%
Typical Applications
Blanking Dies Jewelers Hobs
Engraving Tools Paper Knives
Forming Tools Taps (Hand)
Gauges Trim Dies
Hardening

Note: Full hardness will only be attained in sections less than about 3 inches thick.

Critical Temperature: 1370F(745C).

Preheat: 1250/1350F(675/730C)

High Heat: 1450/1500F(790/815C), hold 10/30 minutes at temperature. Quench: Quench in oil to hand warm, 150F(65C).

Temper: 350/600F(175/315C); hold one hour per inch of thickness, two hours minimum, four hours preferred.

Cryogenic treatments: Refrigeration treatments may improve long-term dimensional stability by transforming retained austenite. Refrigeration treatments should be performed after at least one temper, to minimize risk of cracking, and should always be followed by a temper.
Typical Properties
Hardness and Impact Toughness Data
Oil Quenched from 1475F(800C).
Tempering
Temp.
Hardness
HRC
Toughness,
Charpy C-notch
°F
°C
ft-lbs
Joules
AQ 63-65 – –
300 150 63-65 14 19
350 175 62-64 28 38
400 205 61-63 30 41
450 230 60-62 – –
500 260 58-60 30 41
600 315 55-57 32 43
700 370 51-53 – –
800 425 48-50 – –
900 480 43-45 – –
1000 540 39-41 – –
Size Change During Hardening
Hardening
Temp.
Tempering
Temp.
HRC
Longitudinal
Size Change
%
°F
°C
°F
°C
1475
800
300
150
64
+.12
1475
800
400
205
62
+.14
1475
800
450
230
61
+.18
Surface Treatments

Ketos can be given standard surface treatments such as hard chrome plating if desired. Nitriding is not generally practical due to a substantial loss of core hardness.

Annealing
A. Heat to 1425/1450F(775/790C), hold two hours, cool slowly, 50F(30C) per hour maximum, to below 1000F(540C), then air cool.
OR
B. Heat to 1425/1450F(775/790C), hold 2 hours, cool to 1275F(690C) 6 hours, then air cool.

Typical annealed hardness: 187/221 BHN

Stress Relieving
Annealed Material: 1100/1300F(595/740C), hold 2 hours, cool in still air.

Hardened Material: 50F(30C) below last tempering temperature, hold two hour, cool in still air.

Welding
Use oil-hardening (O1) tool steel filler material.

Annealed material: Preheat to 400/600F(205/315C). Maintain over 400F(205C) during welding. Allow to cool to hand warm (150F(65C) after welding. Reanneal, or temper 1250/1300F(675/705C) for 6 hours.

Hardened material: Preheat to 50F(30C) below tempering temperature (300F(150C) minimum). Maintain over 300F(150C) during welding. Allow to cool to hand warm (150F(65C) after welding. Retemper twice at 25/50F(15/30C) below original tempering temperature.

Physical Properties
Modulus of Elasticity ...................................................................30 psi x 106 (207 GPa)
Density .......................................................................................0.283 lb/in3 (7850 kg/m3)
Specific gravity ............................................................................................................7.85
Thermal Conductivity ................................... 20 BTU/hr/ft/°F(200F) 34.5 W/m°K(95C)
Thermal Expansion
Temperature
Range
Coefficient of Thermal
Expansion
°F
°C
in/in/°Fx10-6
mm/mm/°Cx10-6
RT/400
RT/205
7.0
12.6
RT/800
RT/425
7.4
13.3
RT/1000
RT/540
7.8
14.0
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