303 stainless steel plate

Alloy 303 is a non-magnetic, austenitic stainless steel that is not hardenable by heat treatment. It is the free machining modification of the basic 18% chromium / 8% nickel stainless steel. Alloy 303 was specially designed to exhibit improved machinability while maintaining good mechanical and corrosion resistant properties Due to the presence of sulfur in the steel composition, Alloy 303 is the most readily machineable austenitic stainless steel; however, the sulfur addition does lower Alloy 303’s corrosion resistance to below that of Alloy 304. Like other austenitic grades, Alloy 303 demonstrates excellent toughness, although the sulfur does reduce this a little as well.

Alloy 303 is resistant to mildly corrosive environments. However, the alloy’s corrosion resistance is inferior to 304 in most applications. Its corrosion resistance is superior to 416, another free-machining grade, but is somewhat inferior to other 400 series stainless steels which do not contain higher sulfur levels. In order to obtain optimal corrosion resistance, it is recommended that Alloy 303 be chemically treated to remove sulfides from the final surfaces.

Chemical Composition (%) of 303 Stainless Steel Plate

Chromium	Nickel	Carbon	Manganese	Phosphorus
17.0 min.-19.0 max	8.0 min.-10.0 max.	0.10	2.00	0.20
Sulfer	Silicon	Copper	Nickel	Iron
0.15-0.35	1.00	1.00	0.110	Balance

Mechanical Properties of 303 Stainless Steel Plate

Yield Strengtd 0.2% Offset		Ultimate Tensile Strengtd		Elongation in 2 in.	Hardness
psi (min.)	(MPa)	psi (min.)	(MPa)	% (min.)	(max.)
45,000	310	85,000	586	50	202 (HBN)

Physical Properties of 303 Stainless Plate

Density lb/inᶟ	0.290
Density g/cmᶟ	7.89
Melting Point	2552°F
Thermal Conductivity at 212°F (100°C)	112 BTU/hr/ft²/ft/°F
Thermal Conductivity at 212°F (100°C)	16.2 W/m-°K
Electrical Resistivity	28.3 Microhm-in at 68°C
Electrical Resistivity	72.0 Microhm-cm at 20°C

Machining Operation Speed for 303 Stainless Plate

Machinability	High Speed Tooling		Carbide Tooling		Deptd, Widtd or Diameter of Tool
Machinability	Speed (sfm)	Feed (in./rev.)	Speed (sfm)	Feed (in./rev.)	(in.) (dia./in.)
Turning	115 135	0.0150 0.0050	375 600	0.025 0.007	0.005-0.200 0.002-0.004
Cut-off	90 100	0.0015 0.0025	275 325	0.002 0.004	¹/₁₆ ¹/₄
Forming	100 100	0.0020 0.0015	375 350	0.003 0.002	1 2
Drilling	70 85 100	0.0060 0.0100 0.0200	— 700 800	— 0.005 0.007	¹/₄ ¹/₂ 1-2
Reaming	90 90	0.0050 0.0150	— —	— —	¹/₄ 1-2
End Milling	130 130	0.0030 0.0060	300 350	0.004 0.009	¹/₂ 1-2
Tapping and tdreading	10 40	— —	— —	— —	7 tdreads/in. 25 tdeads/in.