Properties This article has property data, click to view

Stainless Steel - Grade 304 (UNS S30400)

Chemical Formula

Fe, <0.08% C, 17.5-20% Cr, 8-11% Ni, <2% Mn, <1% Si, <0.045% P, <0.03% S

Topics Covered

Background

Key Properties

Composition

Mechanical Properties

Physical Properties

Grade Specification Comparison

Possible Alternative Grades

Corrosion Resistance

Heat Resistance

Heat Treatment

Welding

Machining

Dual Certification

Applications

Background

Grade 304 is the standard "18/8" stainless; it is the most versatile and most widely used stainless steel, available in a wider range of products, forms and finishes than any other. It has excellent forming and welding characteristics. The balanced austenitic structure of Grade 304 enables it to be severely deep drawn without intermediate annealing, which has made this grade dominant in the manufacture of drawn stainless parts such as sinks, hollow-ware and saucepans. For these applications it is common to use special "304DDQ" (Deep Drawing Quality) variants. Grade 304 is readily brake or roll formed into a variety of components for applications in the industrial, architectural, and transportation fields. Grade 304 also has outstanding welding characteristics. Post-weld annealing is not required when welding thin sections.

Grade 304L, the low carbon version of 304, does not require post-weld annealing and so is extensively used in heavy gauge components (over about 6mm). Grade 304H with its higher carbon content finds application at elevated temperatures. The austenitic structure also gives these grades excellent toughness, even down to cryogenic temperatures.

Key Properties

These properties are specified for flat rolled product (plate, sheet and coil) in ASTM A240/A240M. Similar but not necessarily identical properties are specified for other products such as pipe and bar in their respective specifications.

Composition

Typical compositional ranges for grade 304 stainless steels are given in table 1.

Table 1. Composition ranges for 304 grade stainless steel

Grade

C

Mn

Si

P

S

Cr

Mo

Ni

N

304

min.

max.

-

0.08

-

2.0

-

0.75

-

0.045

-

0.030

18.0

20.0

-

8.0

10.5

-

0.10

304L

min.

max.

-

0.030

-

2.0

-

0.75

-

0.045

-

0.030

18.0

20.0

-

8.0

12.0

-

0.10

304H

min.

max.

0.04

0.10

-

2.0

-

0.75

-0.045

-

0.030

18.0

20.0

-

8.0

10.5

-

Mechanical Properties

Typical mechanical properties for grade 304 stainless steels are given in table 2.

Table 2. Mechanical properties of 304 grade stainless steel

Grade

Tensile Strength (MPa) min

Yield Strength 0.2% Proof (MPa) min

Elongation (% in 50mm) min

Hardness

Rockwell B (HR B) max

Brinell (HB) max

304

515

205

40

92

201

304L

485

170

40

92

201

304H

515

205

40

92

201

304H also has a requirement for a grain size of ASTM No 7 or coarser.

Physical Properties

Typical physical properties for annealed grade 304 stainless steels are given in table 3.

Table 3. Physical properties of 304 grade stainless steel in the annealed condition

Grade

Density (kg/m3)

Elastic Modulus (GPa)

Mean Coefficient of Thermal Expansion (μm/m/°C)

Thermal Conductivity (W/m.K)

Specific Heat 0-100°C (J/kg.K)

Electrical Resistivity (nΩ.m)

0-100°C

0-315°C

0-538°C

at 100°C

at 500°C

304/L/H

8000

193

17.2

17.8

18.4

16.2

21.5

500

720

Grade Specification Comparison

Approximate grade comparisons for 304 stainless steels are given in table 4.

Table 4. Grade specifications for 304 grade stainless steel

Grade

UNS No

Old British

Euronorm

Swedish SS

Japanese JIS

BS

En

No

Name

304

S30400

304S31

58E

1.4301

X5CrNi18-10

2332

SUS 304

304L

S30403

304S11

-

1.4306

X2CrNi19-11

2352

SUS 304L

304H

S30409

304S51

-

1.4948

X6CrNi18-11

-

-

These comparisons are approximate only. The list is intended as a comparison of functionally similar materials not as a schedule of contractual equivalents. If exact equivalents are needed original specifications must be consulted.

Possible Alternative Grades

Possible alternative grades to grade 304 stainless steels are given in table 5.

Table 5. Possible alternative grades to 304 grade stainless steel

Grade

Why it might be chosen instead of 304

301L

A higher work hardening rate grade is required for certain roll formed or stretch formed components.

302HQ

Lower work hardening rate is needed for cold forging of screws, bolts and rivets.

303

Higher machinability needed, and the lower corrosion resistance, formability and weldability are acceptable.

316

Higher resistance to pitting and crevice corrosion is required, in chloride environments

321

Better resistance to temperatures of around 600-900°C is needed…321 has higher hot strength.

3CR12

A lower cost is required, and the reduced corrosion resistance and resulting discolouration are acceptable.

430

A lower cost is required, and the reduced corrosion resistance and fabrication characteristics are acceptable.

Corrosion Resistance

Excellent in a wide range of atmospheric environments and many corrosive media. Subject to pitting and crevice corrosion in warm chloride environments, and to stress corrosion cracking above about 60°C. Considered resistant to potable water with up to about 200mg/L chlorides at ambient temperatures, reducing to about 150mg/L at 60°C.

Heat Resistance

Good oxidation resistance in intermittent service to 870°C and in continuous service to 925°C. Continuous use of 304 in the 425-860°C range is not recommended if subsequent aqueous corrosion resistance is important. Grade 304L is more resistant to carbide precipitation and can be heated into the above temperature range.

Grade 304H has higher strength at elevated temperatures so is often used for structural and pressure-containing applications at temperatures above about 500°C and up to about 800°C. 304H will become sensitised in the temperature range of 425-860°C; this is not a problem for high temperature applications, but will result in reduced aqueous corrosion resistance.

Heat Treatment

Solution Treatment (Annealing) - Heat to 1010-1120°C and cool rapidly. These grades cannot be hardened by thermal treatment.

Welding

Excellent weldability by all standard fusion methods, both with and without filler metals. AS 1554.6 pre-qualifies welding of 304 with Grade 308 and 304L with 308L rods or electrodes (and with their high silicon equivalents). Heavy welded sections in Grade 304 may require post-weld annealing for maximum corrosion resistance. This is not required for Grade 304L. Grade 321 may also be used as an alternative to 304 if heavy section welding is required and post-weld heat treatment is not possible.

Machining

A "Ugima" improved machinability version of grade 304 is available in bar products. "Ugima" machines significantly better than standard 304 or 304L, giving higher machining rates and lower tool wear in many operations.

Dual Certification

It is common for 304 and 304L to be stocked in "Dual Certified" form, particularly in plate and pipe. These items have chemical and mechanical properties complying with both 304 and 304L specifications. Such dual certified product does not meet 304H specifications and may be unacceptable for high temperature applications.

Applications

Typical applications include:

  • Food processing equipment, particularly in beer brewing, milk processing & wine making.
  • Kitchen benches, sinks, troughs, equipment and appliances
  • Architectural panelling, railings & trim
  • Chemical containers, including for transport
  • Heat Exchangers
  • Woven or welded screens for mining, quarrying & water filtration
  • Threaded fasteners
  • Springs

The 630-foot-high (190 m), stainless-clad (type 304) Gateway Arch defines St. Louis's skyline

Source: Atlas Steels Australia

For more information on this source please visit Atlas Steels Australia

 

Date Added: Oct 23, 2001 | Updated: Jun 25, 2014
Comments
  1. Mahmoud Ellithy Mahmoud Ellithy Egypt says:

    I want to know about companies producing SS304 tanks and their offers and how to contact them ....?

    • Amos Stitham Amos Stitham United States says:

      IBI/Global Power
      Engineered-Manufactured-Delivered
      Caldwell, ID
      93716

      (208) 459-6077

      Toll Free: 1 (800) 497-8251

  2. Thanh Tran Thanh Tran United Kingdom says:

    I would like to know 316 and 304 which one is more expensive? or higher quality?

    • Vinay Kumar N Vinay Kumar N India says:

      316 is higher.

      • ugeshkumar s ugeshkumar s India says:

        i want to know list of ss materials and cost

  3. Asrul Aizzad Asrul Aizzad Malaysia says:

    I want to know TIG welding parameter for 304

  4. Musthafa Ismail Musthafa Ismail India says:

    Corrosion Resistance
    Excellent in a wide range of atmospheric environments and many corrosive media. Subject to pitting and crevice corrosion in warm chloride environments, and to stress corrosion cracking above about 60°C. Considered resistant to potable water with up to about 200mg/L chlorides at ambient temperatures, reducing to about 150mg/L at 60°C.

    Pitting and crevice corrosion at what temperature. Please specify.

  5. Brigitta Roselie Brigitta Roselie Indonesia says:

    I want to know how can I find the most updating prices for sus304 in kg (is there any web site)

  6. Tyrone Dunn Tyrone Dunn South Africa says:

    I would like to know if it is acceptable to heat 304 stainless in order to create formswept bends on 6 mm thick angle iron without distorting its metalic properties or reducing its corrosiveness in high humidity coastal areas.

  7. Barry Patterson Barry Patterson United States says:

    Is 304 suitable for a 6" flue pipe from a small coal stove in a hunting camp?

  8. T Arai T Arai United States says:

    Which grade would be best for making an exhaust system for a automobile (specifically a VW Vanagon)? I have seen 304 used, but was thinking that 304H or 316 would be better. Would those grades be available in the required pipe sizes? What would be the trade offs? Strength? Longevity?

    • steve miller steve miller United States says:

      304 and 316 are very expensive and can be overkill in the exhaust application.  Try Cromgard 18-1.  Just Google Cromgard and the company pops up.  Its used a lot in the automotive industry for exhausted systems because of resistance to corrosion and low cost.

    • ihsan durani ihsan durani Islamic Republic of Pakistan says:

      Now a days weight reduction is important goal for automobile applications. so you must use a metal which satisfied the customer and company. 304 and 316 are very high weight and also are costly..............

  9. ugeshkumar s ugeshkumar s India says:

    what is moulding and casting difference between them

    • ihsan durani ihsan durani Islamic Republic of Pakistan says:

      molding is a process of mold making for costing any shape but casting belong to   a process  in which specific shape is given to the materials by using mold. the molten metal is pored into the mold for casting parts..........

  10. Yang Fuqiang Yang Fuqiang People's Republic of China says:

    i want to the elastic moduls of 304 stainless steel at -100~100℃

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of AZoM.com.
Ask A Question

Do you have a question you'd like to ask regarding this article?

Leave your feedback
Submit