Stainless Steel - Grade 430

SX 430 Technical Data

Summary

SX430 is a low-carbon plain chromium ferritic stainless steel. The steel has good corrosion resistance in mildly corrosive environments and good resistance to oxidation at elevated temperatures. In the annealed condition the steel is ductile, does not harden excessively during cold work and can be formed using a large variety of roll forming or mild stretch-bending operations, as well as the more common drawing and bending processes. The steel has limited weldability and should not be used in the as welded condition for dynamic or impact loaded structures. Being a ferritic material, 430 is liable to brittle fracture at sub-zero temperatures, and cannot be used in cryogenic applications. As the steel does not contain nickel or molybdenum, it is cheaper than any of the 300 series steels.

Typical Applications

430 is a simple corrosion and heat-resisting grade and finds application in areas where mildly corrosive conditions occur or where scaling resistance at moderate temperatures is required. Typical applications include: Automotive trim, architectural applications such as industrial roofing and wall cladding, kitchen utensils, sinks, washing machine parts and industrial pipe and tube. Materials handling equipment in the mining and sugar industry. Heat resisting applications up to 759oC.

Chemical Composition
 

Analysis % oC Mn P S Si Cr
ASTM A 240 0.12 max 1.0 max 0.045 max 0.03 max 1.0 max 16.0-18.0
Typical 0.05 0.7 0.021 0.024 0.6 17

Typical properties in the annealed condition

The properties quoted in this publication are typical of mill product and unless indicated should not be regarded as guaranteed minimum values for design purposes. For these purposes refer to the relevant specification.

1. Mechanical properties at room temperature
 

  Typical Minimum
Tensile Strength, MPa 530 450
Proof Strength, 0.2 % , MPa 360 205
Elongation (Percent in Lo=5.65 So) MPa 25 22
Hardness 160 -

2. Properties at elevated temperatures

Short time elevated temperature tensile strength

Temperature, oC 300 400 550 650 750
Strength, MPa 450 430 220 120 50

Creep data
Stress for a creep rate of 1% in 10 000 h

Temperature, oC 550 600 650 700 750
Stress, MPa 50 30 15 5 3

Recommended maximum service temperature

(Oxidising Conditions)

Continuous Service            750 oC
Intermittent Service             850 oC

Note: Service in the temperature range 425 -525 oC for over 100 hours will cause the steel to be brittle on cooling to room temperature.

3. Corrosion resistance

3.1 Aqueous
 

Temperature oC 20 80
Concentration, % mass 1     5     10     20     80     100 1     5     10     20     80     100
Sulphuric Acid 2     2      2       2       2        1  2     2      2       2       2        2 
Nitric Acid 0     0      0       0       1        2 0     0      0       1       1        2
Phosphoric Acid 0     0      2       2       1        0 0     0      2       2       1        1
Acetic Acid 0     0      1       1       1        0 0     2      2       2       2        0

 Key:         0 = resistant    -    corrosion rate less than 100 m/year
                 1 = partly resistant    -    corrosion rate less than 1000 m/year
                2 = non resistant    - corrosion rate more than 1000 m/year

3.2 Atmospheric

The performance of 430 compared with other metals in various environments is shown in the following table. The corrosion rate is based on a 10 year exposure.
 

Environment Corrosion Rate (um/year)
SX 430 Aluminium-3S Mild Steel
Rural 0.0025 0.028 4.3
Marine  0.0381 0.424 25.7
Marine-Industrial 0.0406 0.546 37.1

Welding

430 has adequate weldability for many applications. However it is prone to embrittlement in the weld/haz. The fatigue properties of 430 in the welded condition are poor and it is not recommended for applications where applied tensile or impact loading will be experienced.

Thermal Processing

1. Annealing

Annealed 430 is in the softest and most ductile condition, and may be used for cold-working operations. The annealing temperature range is 760oC followed by cooling in air.

2. Stress relieving

Stress relief after welding is not usually required, although 200-300oC is the recommended stress relieving temperature range.

3. Hot working

Initial forging and pressing temperature range:    1100  - 1150oC
Finishing temperature:                                             below 750oC

Avoid extended holding times above 1000oC as excessive grain growth takes place, which severally reduces ductility

Note: Soaking times to ensure uniformity of temperature are longer for stainless steels than for carbon steels. Use up to 1/2 times the time employed for the same thickness of mild steel.

Cold Working

430 can readily be fabricated by cold working. Typical operations include bending, forming, deep drawing and upsetting.

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