Grades of Stainless Steel - Grade 321

SX 321 Technical Data

Summary

SX 321 is a titanium-stabilised version of SX 304, used in particular applications within the sensitizing temperature range.  Its resistance to sensitization, coupled with its higher strength at high temperature makes it suitable in application where SX 304 will become sensitized, or where SX 304L has insufficient hot strength.  It is not subject to weld decay (intergranular corrosion) when exposed to mildly corrosive environments.  However, welded SX 321 must never be used in highly oxidising environments as it is liable to 'Knife-line' attack.

Typical Applications

SX 321 is today used almost exclusively for service within the sensitizing temperature range (450-850^oC).  In welded ambient temperature applications it has been replaced by SX 304L.  Some typical areas of application are:
                Furnace components.
                Superheater and afterburner parts.
                Compensators and expansion bellows.

Chemical Composition (ASTM A240)
 

	C	Mn	P	S	Si	Cr	Ni	Ti
SX Analysis	0.08 max	2.0 max	0.045 max	0.030 max	1.0 max	17.0 - 19.0	9.0 - 12.0	5X%C min 0.5 max
Typical	0.06	1.2	0.020	0.020	0.5	17.5	9.4	0.48

Typical Properties in the Annealed Condition

The properties quoted in this publication are typical of mill products.  Unless otherwise indicated they should not be regarded as guaranteed minimum values for specification purposes.

1. Mechanical Properties at Room Temperature
 

	Typical	Minimum
Tensile Strength, MPa	580	515
Proof Stress (0.2 % offset), MPa	280	205
Elongation (Percent in Lo = 5.65 So)	60	40
Hardness (Brinell)	163	-
Endurance (fatigue) limit, MPa	260	-

2. Properties at Elevated Temperatures
Short Time Elevated Temperature Tensile Strength

Temperature, oC	600	650	700	750	800	850
Tensile Strength, MPa	390	329	280	230	190	140

Creep data
Stress to develop a creep rate of 1% in the indicated time at the indicated temperature.

Time	Temperature oC	550	600	650	700	800
10 000 h	Stress MPa	180	100	70	40	10
100 000 h	Stress MPa	120	80	50	25	5

Creep Rupture Stress

Time	Temperature oC	500	600	650	700	800
1 000 h	Stress MPa	270	180	140	70	30
10 000 h	Stress MPa	240	130	90	50	10
100 000 h	Stress MPa	200	90	50	15	5

Recommended Maximum Service Temperature
(Oxidising Conditions)

Continuous Service            950^oC
Intermittent Service             870^oC

Thermal Processing
1.    Annealing Heat  from 1050 to 1150^oC and cool in air.  This ensures maximum ductility of the steel.
2.    Stress Relieving SX 321 can be stress-relief annealed within the sensitization temperature range
       450-800^oC without carbide precipitation occurring, thus avoiding the possibility of intergranular corrosion.
3.     Hot working
        Initial forging and pressing temperature:              1150  - 1250^oC
        Finishing temperature:                                                   950^oC
 
 

Note:  Soaking times to ensure uniformity of temperature are up to 12  times that required for carbon steel.  Care must be exercised with this grade, and long soaking times to ensure even distribution of carbides should be employed.  The initial reductions must be light to allow dispersion of carbides in the flow pattern during forging.

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Grades of Stainless Steel - Grade 310

SX 310 Technical Data

Summary

SX 310 is a highly alloyed austenitic stainless steel used for high-temperature applications.  The high chromium and nickel contents give the steel excellent oxidation resistance as well as high strength at high temperatures.  This grade is also very ductile, and has good weldability enabling its widespread usage in many applications.
 

SX 310S is the low carbon version of SX 310 and is suggested for applications where sensitisation, and subsequent corrosion by high temperature gases or condensates during shutdown may pose a  problem.
SX 310 is manufactured in accordance with ASTM A 167 and SX 310S to ASTM A 240.

Typical Applications

SX 310/310S find wide application in all high-temperature environments where scaling and corrosion resistance, as well as high temperature strength and good creep resistance, are required.

Chemical Composition
 

SX	C	Mn	P	S	Si	Cr	Ni
310	0.25 max	2.0 max	0.045 max	0.030 max	1.5 max	24.0 - 26.0	19.0 - 22.0
310S	0.08 max	2.0 max	0.045 max	0.030 max	1.5 max	24.0 - 26.0	19.0 - 22.0

Typical Properties in the Annealed Condition
The properties quoted in this publication are typical of mill production and unless indicated should not be regarded as guaranteed minimum values for specification purposes.

1. Mechanical Properties at Room Temperature
 

	SX 310		SX 310S
	Typical	Minimum	Typical	Minimum
Tensile Strength, MPa	625	515	575	515
Yield Stress (0.2 % offset), MPa	350	205	290	205
Elongation (Percent in 50mm)	50	40	50	40
Hardness (Brinell)	172	-	156	-
Endurance (fatigue) limit, MPa	260	-	260	-

2. Properties at Elevated Temperatures
The values quoted are those for SX 310.
Enquire for data on 310S .

Short Time Elevated Temperature Tensile Strength

Temperature, oC	550	650	750	850	950	1050
Tensile Strength, MPa	550	430	280	180	90	50

Creep data
Stress to develop a creep rate of 1% in the indicated time at the indicated temperature.
 

Time	TemperatureoC	550	600	650	700	750	800
10 000 h	Stress MPa	110	90	70	40	30	15
100 000 h	Stress MPa	90	75	50	30	20	10

Creep Rupture Stress

Time	Temperature oC	600	700	800	900	1000
1 000 h	Stress MPa	190	110	50	35	15
10 000 h	Stress MPa	170	70	35	20	10
100 000 h	Stress MPa	110	55	25	10	2

Recommended Maximum Service Temperature
(Oxidising Conditions)
Continuous                     1150^oC
Intermittent                      1035^oC

Thermal Processing
1.    Annealing.  Heat from 1050 to 1150^oC and water quench.  This treatment ensures that all carbides are in
       solution.
2.    Hot working
       Initial forging and pressing:                                    1150  - 1200^oC
       Finishing temperature:                                            above 950^oC

Note:  Soaking times to ensure uniformity of temperature are up to 12  times that required for the same thickness of mild steel.

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Grades of Stainless Steel - Grade 309

SX 309 Technical Data

Summary

SX 309 is a highly alloyed austenitic stainless steel used for its excellent oxidation resistance, high temperature strength and creep resistance.  The lower nickel content of SX309 improves resistance to sulphur attack at high temperatures.  It is tough and ductile, and can be readily fabricated and machined.  SX 309S is the low-carbon version of SX 309, and is recommended for applications where sensitisation, and subsequent corrosion by high temperature gases or condensates during shutdown may pose a problem.
SX 309 is manufactured to ASTM A 167 and SX 309S to ASTM A240 specifications.

Typical Applications
SX 309 / 309S is used exclusively for its high temperature oxidation resistance.  It is common for SX 309, 310 and 321 to be used in the same piece of equipment in the various temperature regions.

Chemical Composition (ASTM A240)
 

SX	C	Mn	P	S	Si	Cr	Ni
309 309S	0.20 max 0.08 max	2.00 max	0.045 max	0.030 max	1.00 max	22.0 - 24.0	12.0 - 15.0

 
Typical Properties in the Annealed Condition
The properties quoted in this publication are typical of mill production and unless indicated should not be regarded as guaranteed minimum values for specification purposes.

1.    Mechanical Properties at Room Temperature
 

	SX 309		SX 309S
	TYPICAL	MIN	TYPICAL	MIN
Tensile Stength       MPa	560	515	540	515
Proof Stress (0.2% Offset)                    MPa	285	205	280	205
Elongation  (Percent in 50 mm)	54	40	54	40
Hardness (Brinell)	164		159
Endurance (fatigue) limit                       MPa	260		260

2.    Properties at Elevated Temperatures
The values quoted are those for SX 309
Short Time Elevated Temperature Tensile Stress
 

Temperature	oC	550	650	750	850	950	1 050
Tensile Stress	MPa	440	360	240	150	70	30

Creep Data
Stress to develop a creep rate of 1% in the time indicated at the temperature indicated.
 

Time	TemperatureoC	550	600	650	700	750	800
10 000 h 100 000 h	Stress MPa  Stress MPa	100 75	80 50	60 30	30 20	25 10	10 5

Creep Rupture Stress
 

Time	Temperature oC	600	700	800	900	1 000
1 000 h 10 000 h 100 000 h	Stress MPa Stress MPa Stress MPa	180 150 100	90 50 40	35 30 20	20 10 5	5 2 -

Maximum Recommended Service
Temperature
(Oxidising Conditions)

Continuous                            1 100^oC
Intermittent                                980^oC
 

Thermal Processing
1.    Annealing.  Heat between 1 050^oC and 1 150^oC and water quench.  This treatment ensures that all carbides are in solution.
2.    Stress Relieving  250-400^oC for 1 hour.
3.    Hot Working
Initial forging and pressure                            1 150-1 200^oC
Finishing temperature                                           1 000^oC

Note:  Soaking times to ensure uniformity of temperature are up to 12 times that required for mild and carbon steels.

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Grades of Stainless Steel - Grade 316

SX 316 / 316L Technical Data

Summary

SX 316 is an improved version of SX 304, with the addition of molybdenum and a slightly higher nickel content. The resultant composition of SX 316 gives the steel much increased corrosion resistance in many aggressive environments.  The molybdenum makes the steel more resistant to pitting and crevice corrosion in chloride-contaminated media, sea water and acetic acid vapours.   The lower rate of general corrosion in mildly corrosive environments gives the steel good atmospheric corrosion resistance in polluted marine atmospheres.
SX 316 offers higher strength and better creep resistance at higher temperatures than SX 304.  SX 316 also possesses excellent mechanical and corrosion properties at sub-zero temperatures.  When there is a danger of corrosion in the heat-affected zones of weldments, the low-carbon variety SX 316L should be used.  SX 316 Ti, the titanium-stabilised version, is used for its resistance to sensitization during prolonged exposure in the 550^oC-800^oC temperature range.

Typical Applications

Because of its superior corrosion and oxidation resistance, good mechanical properties and fabricability, SX 316 has applications in many sectors of industry.  Some of these include:
Tanks and storage vessels for corrosive liquids.
Specialised process equipment in the chemical, food, paper, mining, pharmaceutical and petroleum industries.
Architectural applications in highly corrosive environments.

Chemical Composition (ASTM A 240)
 

	C	Mn	P	S	Si	Cr	Ni	Mo	Ti
SX316 SX316L SX316Ti	0.08 max 0.03 max 0.08 max	2.0 max	0.045 max	0.030 max	1.0 max	16.0 to 18.0	10.0 to 14.0	2.00 to 3.00	- 0.5 max 5X%C

Typical properties in the annealed condition
The properties quoted in this publication are typical of mill products and unless indicated must not be regarded as guaranteed minimum values for specification purposes.

1. Mechanical properties at room temperature
 

	SX316		SX316L		SX316Ti
	Typical	Minimum	Typical	Minimum	Typical	Minimum
Tensile Strength, MPa	580	515	570	485	600	515
Proof Stress (0.2 % offset), MPa	310	205	300	170	320	205
Elongation (Percent in L = 5.65 So)	55	40	60	40	50	40
Hardness (Brinell)	165	-	165	-	165	-
Erichsen Cup Test Value mm	8 - 10	-	10 - 11	-	-	-
Endurance (fatigue) limit, MPa	260	-	260	-	260	-

2. Properties at elevated temperatures
The values given refer to SX 316 and SX 316 Ti only as strength values for SX 316L fall rapidly above 425^oC.

Short Time Elevated Temperature Tensile Strength

Temperature, C	600	700	800	900	1000
Strength, MPa	460	320	190	120	70

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

Temperature, oC	550	600	650	700	800
Stress, MPa	160	120	90	60	20

Recommended Maximum Service Temperature
(Oxidising conditions)

Continuous Service            925^oC
Intermittent Service             870^oC

3. Properties at Sub-Zero Temperatures
( SX 316 )
 

Temperature	oC	-78	-161	-196
Proof Strength (0.2% Offset)	MPa	400	460	580
Tensile Strength	MPa	820	1150	1300
Impact Strength (Charpy V-Notch)	J	180	165	155

4. Corrosion Resistance

4.1    Aqueous
         For specific conditions, consult VRN technical staff.  As a rough guide, the following examples are given
         for pure acid-water mixtures.
 

TemperatureoC	20	80
Concentration, (-% by mass)	10       20       40       60       80       100	10       20       40       60       80       100
Sulphuric Acid	0          1         2         2         1          0	2          2         2        2         2         2
Nitric Acid	0          0         0         0         0          1	0          0         0        0         1         2
Phosphoric Acid	0          0         0         0         1          2	0          0         0        0         1         2
Formic Acid	0          0         0         1         1          0	0          0         1        1         1         0

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

4.2    Atmospheric
          The performance of SX 316 compared with other metals in various environments is shown in the
          following table.  Corrosion rate is based on a 5 year exposure.
 

Environment	Corrosion Rate (mm/year)
	SX 316	Aluminium-3S	Mild Steel
Rural	0.0025	0.025	5.8
Marine	0.0076	0.432	34.0
Marine-Industrial	0.0051	0.686	46.2

Note:  For corrosion resistance of SX 316 relative to other types, see the section in Comparative Data.

4.3    Thermal Processing

4.3.1 Annealing. Heat from 1 010^oC to 1 120^oC and cool rapidly in air or water.  The best corrosion
          resistance is obtained when the final annealing temperature is above 1 070^oC.

4.3.2 Stress relieving.  Heat from 200 - 400^oC and air cool.

4.3.3 Hot working
          Initial forging and pressing:                                    1150  - 1200^oC
          Finishing temperature:                                            above 900^oC
          For upsetting operations, forgings
          should be finished between:                                   930 and 980^oC
          All hot working operations should be followed by annealing.

Note:  Soaking times to ensure uniformity of temperature are up to 12  times that required for the same thickness of mild steel.

Cold Working

SX 316 / 316L, being extremely tough and ductile, can be readily fabricated by cold working. Typical operations include bending, forming, deep drawing and upsetting. 

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