What is stainless steel

Stainless steel is an alloy containing over 12% chromium, providing strong corrosion resistance against common environmental factors such as acids, alkalis, and salts.
By chemical composition, it is divided into magnetic chromium-based stainless steel and non-magnetic nickel-chromium stainless steel.
In terms of crystal structure, the main types include martensitic (13Cr), ferritic (18Cr), and austenitic (18-8 stainless steel).

AUSTENITIC

The 200 and 300 series, such as SUS 304, are commonly known as 18-8 stainless steel (18% chromium, 8% nickel).
They are non-magnetic, not heat-treatable, and offer excellent workability.

Main applications include kitchenware, construction, medical tools, food processing, transportation, and machinery parts.

MARTENSITIC

A typical grade is 410, containing about 13% chromium and low carbon.
It is magnetic, heat-treatable for increased strength, but less formable.

Due to its low nickel content, corrosion resistance is lower than 304, making it suitable only for mild environments. Common uses include bearings, medical tools, and cutlery.

FERRITIC

A typical grade is 430, with 16–18% chromium and low carbon content. It is magnetic, highly formable, and not hardenable by heat treatment.

Common uses include kitchenware, wire mesh, and decorative items.

Type Hardenability Oxidation High Temperature Low Temperature Weldability Magnetic
Resistance Strength Toughness

Austenitic
Ferritic
Martensitic

No
No
Yes

Excellent
Excellent
Poor

Excellent
Poor
Good

Excellent
Poor
Poor

No
Yes
Yes

Other Types
Precipitation Hardening Stainless Steel
Contains about 17% chromium and 4% nickel (600 series).
Can be hardened by heat treatment; offers high strength, corrosion resistance, and heat resistance.
Used in aerospace and precision components.

Duplex Stainless Steel
Typically contains 22% chromium, 9% nickel, and 3% molybdenum.
Combines ferritic and austenitic structures, such as Alloy 2205.
Known for high strength, excellent corrosion resistance, and good machinability.
Common in chemical, marine, oil & gas, and pulp industries.

Stainless Steel
Chemical Composition

TYPE

GRADE

C

Mn

Si

P

S

Ni

Cr

Mo

AUSTENITIC

SUS304

0.08 2.00 1.00 0.045 0.030 8.00~ 18.00~ -
MAX MAX MAX MAX MAX 10.50 20.00

SUS304L

0.03 2.00 1.00 0.045 0.030 9.00~ 18.00~ -
MAX MAX MAX MAX MAX 13.00 20.00

SUS304S

0.04 1.00~ 0.75 0.040 0.030 10.00~ 18.00~ -
MAX 2.00 MAX MAX MAX 10.50 20.00

SUS309

0.08 2.00 1.00 0.040 0.030 12.00~ 22.00~ -
MAX MAX MAX MAX MAX 15.00 24.00

SUS310S

0.08 2.00 1.50 0.045 0.030 19.00~ 24.00~ -
MAX MAX MAX MAX MAX 22.00 26.00

SUS316

0.08 2.00 1.00 0.045 0.030 10.00~ 16.00~ 2.00~
MAX MAX MAX MAX MAX 14.00 18.00 3.00

SUS316L

0.03 2.00 1.00 0.045 0.030 12.00~ 16.00~ 2.00~
MAX MAX MAX MAX MAX 15.00 18.00 3.00

SUS305

0.12 2.00 1.00 0.045 0.030 10.00~ 17.00~ -
MAX MAX MAX MAX MAX 13.00 19.00

MANTENSITIC

SUS410

0.15 1.00 1.00 0.040 0.030 0.60 11.50~ -
MAX MAX MAX MAX MAX MAX 13.00

FERRITIC

SUS430

0.12 1.00 0.75 0.040 0.030 0.60 16.00~ -
MAX MAX MAX MAX MAX MAX 18.00

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