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TOKKIN™ 350│Precipitation Hardening Stainless Steel for Bellows

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Main applications

Welded bellows, actuated valves for air conditioners, diaphragms for cooling equipment


Product size range

Thickness: 0.010mm-2.0mm  

Width  : 3.0mm-300mm

 
Manufacturing sites

JAPAN


  • Product overview Features
  • Standards & Chemical composition
  • Tokkin Advantages
  • Physical Properties Mechanical properties
  • Heat treatment

Product Overview

TOKKIN™ 350 is a precipitation hardening stainless steel with excellent yield strength and cyclic fatigue strength. Compared to other stainless steels, it has better weldability, corrosion resistance, and oxidation-resistant properties.

 

TOKKIN™ 350 Equivalency materials

AM350, UNS S35000, SUS633, AMS 5548, ASTM A693

 

Features

TOKKIN™ 350 corresponds to JIS SUS633, and is a chromium–nickel–molybdenum stainless steel.

It has excellent workability when solution heat treated or annealed, and boasts high strength when heat treated. It also has excellent yield strength and cyclic fatigue strength.

 

How is TOKKIN™ 350 different from other precipitation hardening stainless steels?

Thanks to a higher Mo content than other precipitation hardening stainless steels (SUS631 and SUS632J1), TOKKIN™ 350 has excellent corrosion resistance and oxidation-resistant properties against sulfuric acid, hydrochloric acid, and other substances. It does not contain aluminum or titanium, which gives it excellent weldability.

For this reason, TOKKIN™ 350 is frequently used in applications requiring long life such as bellows, actuated valves for air conditioners, and diaphragms for cooling equipment.

 

Standard

TOKKIN

Designation

USA

others

Japan

UNS

AMS

JIS

TOKKIN™ 350

S35000

5548

AM350

SUS633

 

Chemical composition

TOKKIN

Designation

Chemical composition(%)

C

Si

Mn

P

S

Cr

Ni

Mo

N

その他

TOKKIN™ 350

0.07~

0.11

≦0.50

0.50~

1.25

≦0.040

≦0.030

16.00~

17.00

4.00~

5.00

2.50~

3.25

0.07~

0.13

Bal

Tokkin Advantages

 High quality and reliability

Our ability to produce uniform strength and thickness tolerances that are impossible to achieve using regular materials allows us to manufacture products that demonstrate stable strength in spring applications.

 

Moreover, we can produce excellent fatigue resistance and reliability by adjusting material structure and by creating a high degree of cleanliness via the careful management of manufacturing history and the adjustment of chemical composition.

 

 Ultrathin foils

We can manufacture ultra thin sheets of 0.010 to 0.099 mm.

 

 Flexible, small-lot production

We can manufacture standard lots weighing 300 kg,

and are also happy to consider smaller lots upon consultation.

(Requests for small-lot orders will be dealt with on a case-by-case basis.)

 

 Ability to adjust materials to desired hardness

We make products to order, and can adjust hardness as required.

 

 Select your surface finish

By changing the roll used in the rolling process, we can offer a bright or dull finish.

If required we can also provide a hairline finish (outsourced).

Physical properties

Finish

Density

Specific heat

Electric resistance

Coefficient of thermal expansion

Thermal conductivity

Young's modulus

g/cm3

J(kg·K)

μΩ·cm

(25~100゜C)10-6/K

(100ºC)W/(m·K)

N/mm2

Annealed

7.92

461

79

15.2

15.4

200,000

SCT 850

7.81

461

79

11.3

15.4

196,000

 

Mechanical properties

Finishing condition

Annealed (BA 2B)

SCT 850

Hardness

Tensile strength

Yield strength

Elongation

Hardness

Tensile strength

Yield strength

Elongation

Thickness (mm)

HV

N/mm2

N/mm2

%

HV

N/mm2

N/mm2

%

0.030~0.051

≦266

≦1393

≦641

9≦

412~484

1276≦

1037≦

4≦

0.051~0.127

≦266

≦1372

≦627

10≦

412~484

1276≦

1037≦

6≦

0.127~0.254

≦266

≦1351

≦614

12≦

412~484

1276≦

1037≦

6≦

0.254~0.508

≦266

≦1331

≦600

14≦

412~484

1276≦

1037≦

8≦

 

耐食性

A - Excellent ,  B – Good , C – Moderate , D - Restricted

Humidity

A

Sodium Hydroxide

C

Phosphoric Acid

D

Sea Water

D

hydrochloric Acid

D

Sulfuric Acid

D

Salt Spray (NaCl)

B

Acetic Acid

C

Nitric Acid

B

 

Note:The 4-level rating scale is intended for comparative purposes only. Corrosion testing is recommended; factors which affect corrosion resistance include temperature, concentration, pH, impurities, aeration, velocity, crevices, deposits, metallurgical condition, stress, surface finish and dissimilar metal contact.

Precipitation Hardening

To ensure high hardness, TOKKIN™ 350 is annealed and then precipitation hardened. This process involves a primary hardening treatment, which transforms the metastable austenite structure into a martensite structure, and a precipitation hardening treatment, which completely hardens the material. TOKKIN™ 350 can be hardened using the SCT850 heat treatment conditions shown in the diagram on the right.

Related products
Precipitation Hardening Stainless Steels

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SUS631/632J1 and TOKKIN™ 350 are cold rolled and then precipitation hardened. This process forms an intermetallic compound containing minute amounts of aluminum in the martensite, which enables these materials to achieve extremely high hardness.

Details