Imported Austenitic Stainless Steel

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304

   

Introduction

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.

 

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.

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

 

Stock

Form

Specification

Supply Form

Others

Sheet

Thickness?0.40-4.75mm?General Width?1000?1219?1500mm

Whole Coil or piece of it

Cold Annealed?Surface 2B?2E

Plate

Thickness?4.76-60mm?Width?1500?2000?2500mm?Length?3000?6000?8000?8500mm?Under 10mm plate can be coiled?

Whole Coil or piece of it

Single hot rolling?Solid solution annealed state?Surface 1D

Belt

Thickness?0.10-3.0mm?Width?50-500mm

Whole Coil or Specified size

Cold Annealed?Surface 2B?2E

Bar & Rod

Rolled barΦ5-45mm?Length≤1500mm

Polished Bar?circle?Square?

Solution annealing,descaling

Forged barΦ26-245mm?Length≤4000mm

Weld tube

Outer diameterΦ4.76-135mm?Wall Thickness0.25-4.00mm?Length?≤35000 mm

Base on your requirement

Use for PHE

Seamless Tube

Outer diameterΦ3-114mm?Wall Thickness0.2-4.5mm

Base on your requirement

Use for PHE

Wire

Outer diameterΦ0.1-13mm

Base on your requirement

Ni & Ni alloy, Ti & Ti alloy

Forged piece

roundness and square alloy

Base on your requirement

Steel, Alloy

Flangs

All kinds of Flangs

Base on your requirement

Steel, Alloy

Welding Material

Coil wire Φ0.90mm/1.2mm/1.6mm

Base on your requirement

Certificate of Origin?America, Sweden, Britain, Germany, Austria, Italy, France.

Straight WireΦ1.2mm/1.6mm/2.4mm/3.2mm/4.0mm

Welding rodΦ2.4mm/3.2mm/4.0mm

Tube

Elbow, three links, four links, different diameter size

Base on your requirement

Ni & Ni alloy, Ti & Ti alloy

Explosive bonded laminate

Raw Sheet Thickness≥2mm

Base on your requirement

Ni & Ni alloy, Ti & Ti alloy

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