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. 

Info by  :  http://www.askzn.co.za/tech/tech_grade_316.htm