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302


Melt Practice

We offer this high quality austenitic stainless steel for spring applications. To keep costs at a minimum this alloy is supplied from an electric-arc air melted process. Localized variations in chemistry can cause slight changes in ultimate tensile strength when drawing to fine wire.


Chemistry
  ASTM A313
Carbon 0.12
Manganese 2.00
Silicon 1.00
Phosphorus 0.045
Sulfur 0.030
Chromium 17.0-19.0
Nickel 8.00-10.00
Molybdenum -
Copper -
Nitrogen 0.10
Iron Balance
Cobalt -

Physical Properties
Density 0.285 lbs/in3
Modulus Of Elasticity 28.0 psi x 106
Electrical Resistivity 720 µohms-mm
Thermal Conductivity 16.3 W/mK (100°C)

Thermal Treatment

In wire form, cold worked 302 will gain tensile strength when stress relieved at 350-427°C for 4-6 hours. A reducing atmosphere is preferred, but inert gas can be used. 302 will fully anneal at 1010-1121°C in just a few minutes. There is a carbide precipitation phenomenon that occurs between 427 and 899°C that reduces the corrosion resistance of the alloy. American Society for Testing Materials (ASTM) has described a test method to ensure the alloy has not been damaged.


Applications

302 alloy is the same as 304 alloy except for the 0.12% carbon maximum. In 304 the maximum carbon is 0.08%. Technically, all 304 alloy meets the requirements of 302 alloy, but not all 302 can meet 304 chemistry. Practically, this means in general 302 is harder than 304 with the same amount of cold work. End uses for 302 include: stylets, catheters, guide wires, springs and needles.


Mechanical Properties
%CW Y.S.(psi) U.T.S.(psi) % Elongation
(10" gauge length)
0% 49,000 106,000 48%
20% 125,000 147,000 9.8%
37% 169,000 189,000 3.2%
50% 196,000 220,000 2.6%
60% 222,000 244,000 2.2%
68% 243,000 273,000 2.1%
75% 251,000 289,000 2.4%
80% 282,000 309,000 2.2%
84% 295,000 327,000 2.2%
87% 300,000 332,000 2.3%
90% 319,000 345,000 2.2%
92% 322,000 371,000 2.5%

 

Values are typical and may not represent all diameters. Test method will affect results.


Surface Condition

Stainless steels develop a highly polished appearance as they are drawn to fine diameters. Surface roughness can be less than 5 RMS when processed using SCND* dies and measured with a profilometer. Diameters over 0.040" are finished with polycrystalline dies and exhibit a rougher surface than natural diamond dies. Diameters over 0.100" will have an even rougher surface because they are drawn with carbide dies.

 

*SCND means single crystal natural diamond.

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