Stainless Steel

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About stainless steel

Stainless steel refers to alloy steel containing chrome (Cr) and nickel (Ni) in addition to the 6 iron elements whose Cr content is approximately above 11%. Basically stainless steel should be Fe-Cr alloy containing Cr for about 11% and Ni, Mo, Cu, Al and/or Si, etc. are added to improve corrosion resistance, mechanical properties, processing properties and other properties.
As the primary raw materials are Cr and Ni, they are classified into 2 major categories: Cr and Cr-Ni. They are also classified into categories of martensitic, ferrite and austenitic in terms of metal composition. Also, there are other stainless steel materials such as austenitic/ferrite stainless steel and precipitationhardened stainless steel, etc.

● Stainless steel categories

Categories  Cr Cr-Ni
Metal composition  Martensitic
Ferrite  Austenitic
Hardening  Quenching hardening
Non-quenching hardening
Processing hardening

● Effects of each element on performance

Element  Performance improvement
Low carbon  Corrosion resistance(resistance to grain boundary corrosivity) 
High carbon  Strength and hardness
Mo  Corrosion resistance(resistance to porous corrosion) 
Cu  Acid resistance
Ti・Nb Corrosion resistance(resistance to grain boundary corrosivity) 
Si・Al  Oxidation resistance
S・Se  Machinability

Types and features of stainless steel

Classification code  Features
SUS302  Standard type 18Cr-8Ni steel. SUS303 and SUS304 are both improved variants of SUS302. Addition of Ni improves corrosion resistance and mechanical properties.
SUS303  Machinability is improved by addition of S and P to SUS302. However, its corrosion resistance are relatively low. Mo is added to improve the corrosion resistance. 
SUS304
SUS304L 
This is an improved variant of SUS302 and features smaller amount of carbon and is superior in corrosion resistance and weldability. This is the most standard product among austenitic stainless steel. SUS304L has carbon content lower than that of SUS304 and the resistance to grain boundary corrosion and weldability are improved.
SUS310S  This has good corrosion resistance and oxidation resistance as well as excellent high-temperature properties due to addition of Ni and Cr and is used as heat resistant steel. This reduces the processing hardening by cold processing while weakening its magnetic property, so it is used as low process hardening steel and nonmagnetic steel. 
SUS316
SUS316L 
This has good corrosion resistance and acid resistance as well as high-temperature strength due to addition of Mo and is used as heat resistant steel. SUS316L has carbon content lower than that of SUS316 and the resistance to grain boundary corrosion and weldability are improved.
SUSXM7  Cu is added to SUS304 to suppress the processing hardening in cold processing.
SUS430  This is a standard type of 18Cr steel, having a good cold processing property and corrosion resistance. Because of its inexpensive price, it is widely used in many applications.
SUS434  Mo is added to SUS430 to improve the corrosion resistance.
SUS410  Representative martensitic stainless steel This has excellent mechanical properties and corrosion resistance after heat treatment. 
SUS403  Corrosion resistance and toughness after heat treatment are improved with Si and Cr composition range narrowed down. This is used for valves, pump shafts, edges, bolts, nuts, steam turbine blades and jet engine components, etc.
SUS416  Machinability of 13Cr steel is improved by addition of S and P. Its corrosion resistance are relatively lower than the standard type.
SUS431  Toughness and corrosion resistance are improved by addition of Ni and Cr, respectively and its corrosion resistance is the best among martensitic materials that endure heat treatment. This is used for papermaking machines, marine shafts and aerospace components, etc.
SUS440C  This has the highest hardness among stainless steel materials and excellent abrasion resistance, so this is used for dice and ball bearings, etc. 
SUS631J1  This is precipitation-hardened stainless steel with the highest heat resistance among JIS steel types and used for thin plates and wire springs.  

Chemical components and mechanical properties of various stainless steel materials

● Austenitic

Classification code
Chemical components(%) Mechanical property
C Si Mn P S Ni Cr Mo Others Tensile strength
(N/mm2)
Extension
(%)
Brinell hardness
(HB)
SUS302 0.15
or less
1.00
or less
2.00
or less
0.045
or less
0.03
or
less
 8.00 - 10.00 17.00 - 19.00 - - 520 or above 40 or above 187 or less
SUS303 0.15
or less
1.00
or less
2.00
or less
0.20
or less
0.15
or above
 8.00 - 10.00 17.00 - 19.00 0.60 or less
- 520 or above 40 or above 187 or less
SUS304 0.08
or less
1.00
or less
2.00
or less
0.045
or less
0.03
or
less
 8.00 - 10.50 18.00 - 20.00 - - 520 or above 40 or above 187 or less
SUS304L 0.03
or less
1.00
or less
2.00
or less
0.045
or less
0.03
or
less
 9.00 - 13.00 18.00 - 20.00 - - 480 or above 40 or above 187 or less
SUS310S 0.08
or less
1.50
or less
2.00
or less
0.045
or less
0.03
or
less
19.00 - 22.00 24.00 - 26.00 - - 520 or above 40 or above 187 or less
SUS316 0.08
or less
1.00
or less
2.00
or less
0.045
or less
0.03
or
less
10.00 - 14.00 16.00 - 18.00 2.00 - 3.00 - 520 or above 40 or above 187 or less
SUS316L 0.03
or less
1.00
or less
2.00
or less
0.045
or less
0.03
or
less
12.00 - 15.00 16.00 - 18.00 2.00 - 3.00 - 480 or above 40 or above 187 or less
SUSXM7 0.08
or less
1.00
or less
2.00
or less
0.045
or less
0.03
or
less
 8.50 - 10.50 17.00 - 19.00 - Cu:3.00 - 4.00 480 or above 40 or above 187 or less

● Ferrite

Classification code
Chemical components(%) Mechanical property
C Si Mn P S Ni Cr Mo Others Tensile strength
(N/mm2)
Extension
(%)
Brinell hardness
(HB)
SUS430 0.12 or less 0.75 or less 1.00 or less 0.04 or less 0.03 or less 0.60 or less 16.00 - 18.00 - - 450 or above 22 or above 183 or less
SUS434 0.12 or less 1.00 or less 1.00 or less 0.04 or less 0.03 or less 0.6 or less 16.00 - 18.00 0.75 - 1.25 - 450 or above 22 or above 183 or less


 

● Martensitic

Classification
code
Chemical components(%) Mechanical property
C Si Mn P S Ni Cr Mo Others Tensile strength
(N/mm2)
Extension
(%)
Brinell hardness
(HB)
SUS410 0.15 or less 1.00 or less 1.00 or less 0.04 or less 0.03 or less 0.60 or less 11.50 - 13.50 - - 540 or above 25 or above 159 or above
SUS416 0.15 or less 1.00 or less 1.25 or less 0.06 or less 0.15 or above
0.60 or less 12.00 - 14.00 0.60 or less - 540 or above 17 or above 159 or above
SUS440C 0.95 - 1.20 1.00 or less 1.00 or less 0.04 or less 0.03 or less 0.60 or less 16.00 - 18.00 0.75 or less - 780 or above 15 or less 56HRC or above

●Values in chart are for reference only. They are not guaranteed values.

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