ISO CLASSIFICATION OF METALS
ISO CLASS
P
M
K
N
S
H
MATERIAL TYPE
STEEL (FERRITIC /
MARTENSITIC)
STAINLESS STEEL
CAST IRON
NON-FERROUS
SUPPER ALLOYS
HARDENED STEEL
DESCRIPTION
The most common material group, ranging from unalloyed to high alloyed material, including
steel castings, ferritic and martensitic stainless steels. Machinability is normally good but
differs depending on material hardness and content.
Stainless steel are materials alloyed with a minimum of 12% chromium, other alloys can be
nickel and molybdenum. Different conditions such as ferritic, martensitic, austenitic, and
austenitic-ferritic, make this a large family. They all expose cutting edges to a great deal of
heat, notch wear and built-up-edge.
Cast iron is a short-chipping type of material. Grey cast iron (GCI) and malleable cast iron
(MCI) are quite easy to machine, while others including nodular cast irons (NCI), compact
cast irons (CGI) and austempered cast irons (ADI) are more difficult. All cast irons contain
silicon carbide, which is very abrasive to the cutting edge.
Non-ferrous metals are softer types of metals such as aluminum, copper, brass, etc.
Aluminum with a silicon content of 13% is very abrasive. Generally, high cutting speeds and
long tool life can be expected.
HRSA refers to heat-resistant superalloys, including a great number of high-alloyed iron,
nickel, cobalt, and titanium-based materials. They are sticky, create built-up-edge, work
hardening and generate heat. They are difficult to cut and have a short tool life.
This group covers steels with a hardness between 45-65 HRC and also chilled cast iron
around 400-600 HB. The hardness makes them difficult to machine. The materials generate
heat during cutting and are abrasive to cutting edges.
SUB GROUP
MATERIALS
P1
FREE CUTTING STEEL & STRUCTURAL STEEL
P2
CARBON STEEL AND LOW ALLOY STEEL
P3
MEDIUM ALLOY AND HEAT TREATED STEEL
P4
HIGH ALLOY STEEL
P5
TOOL STEEL
P6
HIGH TENSILE STRENGTH STEEL
M1
FERRITIC STAINLESS STEEL
M2
AUSTENITIC STAINLESS STEEL (GOOD MACHINABILITY)
M3
AUSTENITIC STAINLESS STEEL (MEDIUM MACHINABILITY)
M4
MARTENSITIC STEEL
M5
PH STAINLESS STEEL
K1
GREY CAST IRON
K2
NODULAR CAST IRON
K3
AUSTENITIC CAST IRON
K4
ADI CAST IRON
N1
ALLUMINIUM ALLOYS Si < 12%
N2
ALLUMINIUM ALLOYS Si > 12%
N3
COPPER
N4
BRONZE & BRASS
S1
HEAT RESISTANT ALLOYS (GOOD MACHINABILITY)
S2
HEAT RESISTANT ALLOYS (MEDIUM MACHINABILITY)
S3
HEAT RESISTANT ALLOYS (LOW MACHINABILITY)
S4
LOW ALLOY TITANIUM (GOOD MACHINABILITY)
S5
HIGH ALLOY TITANIUM (MEDIUM MACHINABILITY)
H1
HARDENED STEEL
H2
HARDENED BEARING STEEL
H3
HARDENED TOOL STEEL
H4
HARDENED MARTENSITIC STAINLESS STEEL
H5
HARDENED WHITE CAST IRON
HARDNESS (HB)
APPLICATIONS
MATERIAL GRADES
125 ~ 350
Automotive Parts,
Dies, Machinery,
Bearings
11SMn30
42CrMoV4
100Cr6
16MnCr5
X20Cr13
180 ~ 240
Shafts for Pumps,
Steam & Water
Turbines,
Nuts, Bolts,
Hot Water Heaters
X10CrNiS18-9
X5CrNI18-10
X2CrNiMo18-14-3
X2CrNiMoN22-5-3
X2CrNiMoN22-7-4
130 ~ 260
Pipes,
Cylibder Heads,
Cylinder Blocks,
Gearbox Cases
EN-GJL-250
EN-GJV-400
EN-GJMB-550-4
EN-GJS-500-7
Bush,
Timing Pulleys,
AW-7075
AlSi17Cu5
CW614N
60 ~ 130
200 ~ 350
Landing Gears,
Jet Engines,
Engine Mounts,
Steam Turbines,
Oil & Gas Parts
Inconel718
TiAl6V4
Ti10V2Fe3Al
400 ~ 600
Automotive Parts,
Hand Tools,
Drill Bits
X120Mn12
X40CrMoV5-1