High Hardness 302 Austenitic Stainless Steel By yaang.com

302 austenitic stainless steel, which exhibits excellent hardness and is suitable for spring applications. In order to reduce costs, this stainless steel is directly delivered from an electric-arc air melted process. However, when drawing to fine wire, localized differences in chemistry can induce minimal changes in the final tensile strength.

Table 1 shows the typical chemistry of different elements. The chemistry is for reference only, and must not be employed for specification purposes.

Table 2 gives the physical properties of the 302 stainless steel, and Table 3 the mechanical properties.

Table 1. Typical chemistry of different elements

	FWM Avg. Wt. %	ASTM A313
Carbon	0.10	0.12
Manganese	1.11	2.00
Silicon	0.52	1.00
Phosphorus	0.023	0.045
Sulfur	0.002	0.030
Chromium	18.60	17.0-19.0
Nickel	8.40	8.00-10.00
Molybdenum	0.32	-
Copper	0.36	-
Nitrogen	0.03	0.10
Iron	Balance	Balance
Cobalt	0.16	-

Table 2. Physical properties of 302 stainless steel

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)

Table 3. Mechanical properties of 302 stainless steel

%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%

Thermal Treatment

Cold worked 302 stainless steel in wire form will acquire tensile strength when they are stress relieved from 350°C to 427°C for a period of 4 to 6 h. Here, a reducing atmosphere is usually used, but inert gas can also be employed. The 302 stainless steel can be fully annealed at 1010-1121°C for a short period of time. However, the corrosion resistance of the stainless steel is significantly reduced due to carbide precipitation that occurs between 427°C and 899°C. Nonetheless, a test method has been described by the American Society for Testing Materials (ASTM) which ensures that the stainless steel is not damaged.

Surface Condition

Since stainless steels are drawn to fine diameters, they tend to develop a highly polished appearance. When single crystal natural diamond (SCND) dies are utilized to process stainless steels, the surface roughness can be below 5 RMS. Stainless steels with more than 0.040” diameters are finished by means of polycrystalline dies and tend to have a rougher surface than those processed with natural diamond dies. Similarly, stainless steels with more than 0.100" diameters will exhibit an even rougher surface as they are drawn with carbide dies.

Applications

302 stainless steel is like 304 stainless steel, apart from the 0.12% carbon maximum. The maximum percentage of carbon in 304stainless steel is 0.08%. In principle, all 304 stainless steels fulfill the requirements of 302 stainless steel, but not all 302 stainless steels meet 304 stainless steel chemistry. This means, despite the same amount of cold work, 302 is comparatively harder than 304. The end products of 302 stainless steels include stainless steel pipes, stainless steel flanges, stainless steel pipe fittings, stainless steel tubes.

Conclusion

Yaang offers high quality and high hardness 302 austenitic stainless steel specifically developed for spring applications. Except for the slight difference in carbon maximum, the 302 stainless steel shares the same properties as the 304 stainless steel and is widely used for making medical appliances.

About Yaang Pipe Industry Co., Limited

Established in 2008, Yaang Pipe Industry Co., Limited is a professional organizer and one-stop-shop supplier for steel piping system products, including stainless steel pipes and stainless steel tubes, forged stainless steel flanges and stainless steel pipe fittings, butt-welding stainless steel pipe fittings, stainless steel elbows, stainless steel tees, stainless steel reducer, stainless steel stub end, stainless steel gaskets, stainless steel fasteners, stainless steel valves, Sanitary Services etc. in China. We have devoted to providing the best solutions of steel materials and industrial equipment for our respected customers.

Source: Yaang Pipe Industry Co., Limited (www.yaang.com)

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