Classification of Stainless Steel


Metallurgically, stainless steels are classified into 3 groups:
  1. Martensitic
  2. Ferritic
  3. Austenitic
Martensitic Class:  - This is the straight chromium type of stainless, containing Chromium as it's main alloying element.
It is normally Hard and Brittle, includes 4% - 10% Chromium types and is Air Hardening,
and Magnetic. Preheat and Postheat is necessary when welding.

Ferritic Class:  - Is also straight Chromium type.
Normally is Soft and Ductile., includes the 12% - 28% Chromium types.
It is Magnetic. Preheat and Postheat is necessary when welding

Austenitic Class:  - This steel is of the Chromium-Nickel type.
The Nickel content usually ranges from 7% - 35% with 8% - 10% being the most predominantly used.
It is Strong, Ductile and Impact Resistant
Non-magnetic in the annealed condition, but slightly magnetic when cold worked.
No preheat or Postheat is necessary when welding.

How Heat affects Stainless Steel

Heat and Hardness

  • if you heat the mild carbon steel to 1600 -1900 F and quickly quench, for example immersion in water,
    you will get a Maximum Hardness.
  • If you give the same treatment to Austenitic or Chrome-Nickel steel, you will achieve
    Maximum Softness.

Heat and Corrosion Resistance

  • Carbide precipitation causes the stainless steel to loose its corrosion resisting properties in the areas affected. Best seen at areas of welding, rusty discoloration indicates that the alloy was robbed of its Chromium.
  • Martensitic Stainless Steels are not subject to Carbide Precipitation or loss of corrosion resistance.
    They are considered stable over the entire temperature range.

Heat and Grain growth

  • Martensitic SS are affected by Grain growth of the individual crystals when subjected to elevated welding or forging temperatures
    This grain growth causes the metal to become Brittle.
  • Small crystals can be restored by heat treatments to improve Ductility
  • Pre-heats and post-heats are used to slow down the cooling to avoid excessive hardening and to prevent cracking.
  • Will harden intensely when allowed to Air cool - result in Cracking


Welding Stainless Steels

ClassSeriesPre/Post heatMagneticCooling
Cyan-divider-bar
Martensitic
Ferritic
Austenitic
400
400
300
YES
YES
NEVER
YES
YES
NONMAGNETIC
SLOW
SLOW
N/A
  • A small amount of ferrite in 300 series welds inhibits cracking
  • Only a fully austenitic welds are nonmagnetic
  • Small diameter welding rods help keep the heat to a minimum
  • The suffix "-16" indicated titania-type electrode coating which can be run AC or DC reverse polarity.
    Titania type has a very smooth arc and the metal flows more freely with practically no spatter.
    The bead is thinner and more concave - lack of material frequently causing cracks
  • The suffix "-15" indicated lime-type electrode coating which should be run DC reverse polarity only.
    Less slag than titania type, deposits are sound, high strength. More convex and thicker, no cracking problem.


Stainless & Heat Resisting Steels - Chemical table

TypeCarbonManganPhosp SulphurSiCrNickelMoly SelleniumLess common
Cyan-divider-bar
201 0.15
Max
5.50
7.50
0.0600.0301.00 16.00
18.00
3.50
5.50
-- N
0.25
202 0.15
Max
7.50
10
0.0600.0301.00 17.00
19.00
4.00
6.00
-- N
0.25
Cyan-divider-bar
301 0.15
Max
2.000.0450.0301.00 16.00
18.00
6.00
8.00
---
302 0.15
Max
2.000.0450.0301.00 17.00
19.00
8.00
10.00
---
302 B 0.15
Max
2.000.0450.0302.00
3.00
17.00
19.00
8.00
10.00
---
303 0.15
Max
2.000.20Min
0.15
1.00 17.00
19.00
8.00
10.00
0.60- Zr
0.60
303 Se 0.15
Max
2.000.200.061.00 17.00
19.00
8.00
10.00
-Min
0.15
-
304 0.08
Max
2.000.0450.0301.00 17.00
19.00
8.00
10.00
---
304 L 0.03
Max
2.000.0450.0301.00 18.00
20.00
8.00
12.00
---
305 0.12
Max
2.000.0450.0301.00 17.00
19.00
8.00
10.00
---
308 0.08
Max
2.000.0450.0301.00 17.00
19.00
8.00
10.00
---
309 0.20
Max
2.000.0450.0301.00 22.00
24.00
12.00
15.00
-- -
309 S 0.08
Max
2.000.0450.0301.00 22.00
24.00
12.00
15.00
-- -
310 0.25
Max
2.000.0450.0301.50 24.00
26.00
19.00
22.00
-- -
310 S 0.08
Max
2.000.0450.0301.50 24.00
26.00
19.00
22.00
-- -
314 0.25
Max
2.000.0450.0301.50 17.00
19.00
8.00
10.00
---
316 0.08
Max
2.000.0450.0301.00 16.00
18.00
10.00
14.00
2.00
3.00
--
316 L 0.03
Max
2.000.0450.0301.00 16.00
18.00
10.00
14.00
2.00
3.00
--
317 0.08
Max
2.000.0450.0301.00 18.00
20.00
11.00
15.00
3.00
4.00
--
321 0.08
Max
2.000.0450.0301.00 17.00
18.00
8.00
12.00
- -Ti
5xC
347 0.08
Max
2.000.0450.0302.00
3.00
17.00
18.00
9.00
13.00
-- Ta
10xC
348 0.08
Max
2.000.0450.0302.00
3.00
17.00
19.00
9.00
13.00
-- Cb-Ta | Ta
10xC   | 0.10
Cyan-divider-bar
403 0.08
Max
2.000.0450.0300.50 11.50
13.00
----
405 0.08
Max
2.000.0450.0301.00 11.50
14.50
----
410 0.15
Max
1.000.0400.0301.00 11.50
13.50
----
414 0.15
Max
1.000.0400.0301.00 11.50
13.50
1.25
2.50
---
416 0.15
Max
1.250.060.15 Min1.00 12.00
14.00
-
0.60

0.60
-
416 Se 0.15
Max
1.250.060.15 Min1.00 12.00
14.00
--- Se
0.15 Min
420 Over
0.15
1.000.0400.0301.00 12.00
14.00
----
430 0.12
Max
1.000.0450.0301.00 14.00
18.00
----
430F 0.12
Max
1.250.060.15 Min1.00 14.00
18.00
-
0.60

0.60
-
430F Se 0.12
Max
1.250.060.061.00 14.00
18.00
---Se
0.15 Min
431 0.20
Max
1.000.0450.0301.00 15.00
17.00
1.25
2.50
- --
440A 0.60
0.75
1.000.0400.0301.00 16.00
18.00
-0.75
Max
--
440B 0.75
0.95
1.000.0400.0301.00 16.00
18.00
-0.75
Max
--
440-C 0.95
1.20
1.000.0400.0301.00 16.00
18.00
-0.75
Max
--
440-XH 1.600.50 - -0.4016.00 0.350.80--
446 0.20
Max
1.500.0400.0301.00 23.00
27.00
-- -N
0.25 Max
Cyan-divider-bar
501 0.10
Max
1.000.0400.0301.00 4.00
6.00
-0.40
0.65
- -
502 Over
0.10
1.000.0400.0301.00 4.00
6.00
-0.40
0.65
- -





Master Index  |  Custom Knives  |  Page menu  |  Feedback Animated blue Line
Valid HTML 4.01 Transitional Valid CSS!
Czech flag   This web site was created and is maintained by Tony Hnilica - *AJH* Custom Knives & Services  Czech flag

mail