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SS904L Grade Properties


Chemical Formula

Fe, <0.02% C, 19-23% Cr, 23-28% Ni, 4-5% Mo, <2.0% Mn, <1.0% Si, <0.045% P, <0.035% S, 1.0-2.0% Cu

Introduction

Grade 904L stainless steel is an austenitic stainless steel that is non-stabilized and is accessible with reduced carbon content. This is a high alloy metal added with copper, so as to amend its action against strong reducing acids, such as sulfuric acid. The metal is resistant to crevice corrosion and stress corrosion cracking. Provided non-magnetic products come with ruggedness, excellent form-ability and superior weld-ability. Grade 904L incorporates high amounts of pricey constituents, such as nickel and molybdenum. Presently, applications which employ grade 904L avoid the usage of low-cost duplex stainless steel 2205.

Key Properties

The following subdivisions depict the properties of flat rolled products in ASTM B625. The descriptions may not be same for other products such as tube, bar and pipe.

Composition

The following table gives the compositional levels of grade 904L stainless steels:

Table 1. Composition compasses of grade 904L stainless steels

Grade

C

Mn

Si

P

S

Cr

Mo

Ni

Cu

904L

min.

max.

-

0.02

-

2

-

1

-

0.045

-

0.035

19

23

4

5

23

28

1

2

Mechanical Properties

The veritable mechanical attributes of grade 904L stainless steels are conferred in the following table :

Table 2. Mechanical properties of grade 904L stainless steels

Grade

Tensile Strength (MPa) min

Yield Strength 0.2% Proof (MPa) min

Elongation (% in 50mm) min

Hardness





Rockwell B (HR B)

Brinell (HB)

904L

490

220

36

70-90 typical

150

Physical Properties

The physical strength and capacities of grade 904L stainless steels are mentioned in the following table :

Table 3. Typical physical properties of grade 904L stainless steels

Grade

Density
(kg/m
3)

Elastic Modulus
(GPa)

Mean Co-eff of Thermal Expansion (m/m/0C)

Thermal Conductivity
(W/m.K)

Specific Heat 0-100oC
(J/kg.K)

Elec Resistivity




0-100ðC

0-315°C

0-538°C

At 20ðC

At 500°C



904L

7900

190

15

-

-

11.5

-

500

952

Grade Specification Comparison

The following tabular array provides the approximate grade equivalences of 904L stainless steels:

Table 4. Grade specifications of grade 904L stainless steels

Grade

UNS No

Old British

Euronorm

Swedish SS

Japanese JIS



BS

En

No

Name



904L

N08904

904S13

-

1.4539

X1NiCrMoCuN25-20-5

2562

-

Possible Alternate Grades

The appropriate alternates to 904L stainless steels are cited below :

Table 5. Possible alternative grades to grade 904L stainless steels

Grade

Grounds for selecting grade 904L

316L

 An alternative with reduced cost, but with low-level corrosion resistance.

6Mo

Advanced action against pitting as well as crevice corrosion is essential.

2205

A much kindred corrosion resistance, with the 2205 featuring high mechanical strength, and at a lower expenditure to 904L. (2205 not suited for temperatures more than 300oC.)

Super duplex

Super duplex : Resistant against corrosion is needful, in collaboration with a higher strength than 904L

Corrosion and Heat Resistance

Grade 904L stainless steels have supreme resistance to chloride onset and warm seawater. This grade is also resistant to stress corrosion great is due to the presence of high amounts of nickel in its composition. Moreover, the addition of copper to these forms enables resistance to sulfuric acid and some other reducing agents in mild as well as aggressive conditions. The corrosion action of this grade is in-between between super austenitic grades, with regular 316L austenitic grades and 6% of molybdenum content. Grade 904L has reduced resistance against nitric acid in comparison with the grades of 304L and 310L, which are not included with molybdenum. This steel grade is an appropriate solution apt for cold working and come with optimal resistance against maximal stress corrosion cracking even under critical environments.

Grade 904L stainless steels provides excellent oxidation resistance. Nevertheless, the makeup stability of this grade falls at high temperatures, especially above 400ðC.

Heat Treatment

Grade 904L stainless steels are solution heat-treated at 1090 to 1175ðC, leading by fast cooling. Thermal treatment is appropriate for hardening these forms.

Welding

Welding of the grade 904L can be executed by employing all conventional techniques. This grade does not need pre-heat or post-weld heat treatments. It can be susceptible to hot cracking in strained weldment. The rods and electrodes of this grade are utilized for welding in compliance with AS 1554.6

Fabrication

Grade 904L stainless steels are hygienic steels with reduced sulphur content. These can be machined by employing all modular methods. These grades can be promptly bended to the small radius under cold premises. Although resultant hardening is not needed in most cases, it should be executed when the fabrication is acted under intense stress corrosion cracking states.


Applications

Some of the main usages of grade 904L stainless steels include:

  • Oil refinery components
  • Wiring in electrostatic precipitators
  • Seawater cooling devices
  • Scrubbing plants
  • Paper processing industries
  • Processing of acetic acid
  • Processing of phosphoric acid
  • Processing of sulphuric acid





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