AISI 303 Stainless Steel Properties, SS 303 Density, Hardness, Magnetic, Equivalent (UNS S30300)

AISI 303 stainless steel (UNS S30300) was developed for easy cutting and basically belongs to 18-8 stainless steel. It improves the cutting performance while maintaining good mechanical properties. SS 303 has a higher sulfur content, which reduces the resistance on the cutting tool, but has a negative impact on the corrosion resistance, so the corrosion resistance is not as good as AISI 304 stainless steel.

Datasheet & Specification

The following tables and lists give the stainless steel 303 datasheet and specification including chemical composition, physical properties and mechanical properties, heat treatment, welding, etc.

Chemical Composition

SS 303 material chemical composition is listed in the following table based on cast analysis.

Chemical Composition, %
ASTM	AISI (UNS)	C, ≤	Si, ≤	Mn, ≤	P, ≤	S, ≥	Cr	Ni	Notes
ASTM A582/A582M	303 (UNS S30300)	0.15	1.00	2.00	0.20	0.15	17.0-19.0	8.0-10.0	Free-Machining Stainless Steel Bars
ASTM A581/A581M									Free-Machining Stainless Steel Wire and Wire Rods
ASTM A895									Free-Machining Plate, Sheet, and Strip
ASTM A959									Wrought Stainless Steels
ASTM A473									Stainless Steel Forgings
ASTM A314									Billets and bars for forging

Notes:

• ASTM A582/A582M: Standard Specification for Free-Machining Stainless Steel Bars
• ASTM A581/A581M: Standard Specification for Free-Machining Stainless Steel Wire and Wire Rods
• ASTM A895: Standard Specification for Free-Machining Stainless Steel Plate, Sheet, and Strip
• ASTM A959: Standard Guide for Specifying Harmonized Standard Grade Compositions for Wrought Stainless Steels
• ASTM A473: Standard Specification for Stainless Steel Forgings
• ASTM A314: Standard Specification for Stainless Steel Billets and Bars for Forging

Type 303 Stainless Steel Properties

The tables below list 303 stainless steel properties, including physical and mechanical properties.

Physical Properties

AISI 303 stainless steel physical properties are given in the following lists, including density, thermal expansion, elastic modulus, thermal conductivity, specific heat capacity and electrical resistance.

Notes:

• 10^-6·K^-1 = 10^-6/K
• 1 Ω·mm²/m = 1 μΩ·m
• 1 g/cm3 = 1 kg/dm3 = 1000 kg/m3
• 1 GPa = 1 kN/mm2
• 1 MPa = 1 N/mm2

Physical Properties
303 stainless steel density, g/cm3 (lb/in.3)	7.9 (0.29)
Melting point, °C (°F)	1400-1450 (2550-2590)
Specific heat capacity, J/kg·K (Btu/lb ·°F)	500 (0.12) at 20℃
Electrical resistivity, μΩ·m	0.72 at 20℃
Magnetic permeability	1.02 (Approximate)
Elastic modulus, Gpa (10-6 psi)	193 (28)
Thermal conductivity, W/m·K (Btu/ft · h ·°F)	16.2 (9.4) at 100 °C (212 °F)
	21.5 (12.4) at 500 °C (932 °F)
Coefficient of thermal expansion, 10-6/K (μin./in. ·°F)	17.2 (9.6) at 0-100 ℃ (32-212 °F)
	17.8 (9.9) at 0-315 ℃ (32-600 °F)
	18.4 (10.2) at 0-538 ℃ (32-1000 °F)

Magnetic: SS 303 is non-magnetic in the annealed condition, but may become slightly magnetic due to cold working.

Mechanical Properties

303 steel mechanical properties at room temperature are listed in the following tables.

AISI 303 Mechanical Properties
ASTM	AISI	Conditions	Tensile Strength, MPa (ksi), ≥	0.2% Yield Strength, MPa (ksi), ≥	Elongation in 50 mm (2 in.), %, ≥	Reduction of Area, %, ≥
ASTM A473	303 (UNS S30300)	Annealed	515 (75)	205 (30)	40	50
ASTM A581/A581M		Annealed	585-860 (85-125)
		Cold Worked	795-1000 (115-145)

Brinell Hardness:

• 160, Annealed bar
• 228, Cold drawn

Heat Treatment

Recommended annealing temperatures for AISI 303 wrought stainless steel is 1040 °C (1900 °F).

Typical forging temperature range is 925-1260 °C (1700-2300 °F), (C: 0.08%; S: 0.30%)

Hardening: SS 303 cannot be hardened by heat treatment, but can be hardened by cold working.

Welding

Due to the high P and S content, SS 303 is not recommended for welding. If welding cannot be avoided, AWS E312 filler metal may be considered.

Machinability (Machining)

Increased tool life attained with coated cutting tools

Cutting tool		Coating	Workpiece material	Workpieces machined before resharpening
Type	High-speed tool steel, AISI type			Uncoated	Coated
Broach insert	M3	TiN	Type 303 stainless steel	100,000	300,000
Form tool	T15	TiN		1,840	5,890

Recommended face angles, along with backoff angles for type 303 stainless steel:

• Face angle, 15 degrees;
• Backoff angle:0.5 – 2 degrees.

Speed and feed ranges for the spade drilling are listed in the following table.

Material drilled	Drill diameter, mm (in.)
	25 (1)		50 (2)		75 (3)		100 (4)		125 (5)
	Speed, rev/min	Feed rate, mm/rev (in./rev)	Speed, rev/min	Feed rate, mm/rev (in./rev)	Speed, rev/min	Feed rate, mm/rev (in./rev)	Speed, rev/min	Feed rate, mm/rev (in./rev)	Speed, rev/min	Feed rate, mm/rev (in./rev)
Type 303 and 303 Se	225-275	0.15-0.25 (0.006-0.010)	120-125	0.25-0.38 (0.010-0.015)	75-90	0.38-0.51 (0.015-0.020)	55-65	0.51-0.63 (0.020-0.025)	45-55	0.63-0.76 (0.025-0.030)

Recommended cutting parameters for indexable drills with uncoated and titanium-coated carbide inserts

Material	Drill size		Speed				Feed		Insert style	Grade
			Standard length		Stub length
	mm	in.	m/min	sfm	m/min	sfm	mm/rev	in./rev
AISI 303, 304 and 316, 416	19-30	.75 – 1.1875	45-105	150-350	45-150	150-500	0.08-0.10	0.003-0.004	SPGM	C-2, Uncoated
	32-36.5	1.25-1.4375					0.10-0.13	0.004-0.005	SNMG	C-5, Titanium coated.
	38-47.5	1.50-1.875					0.10-0.15	0.004-0.006	SNMMND
	49-75	1.9375-3					0.13-0.20	0.005-0.008	SNMMND

Nominal speeds and feeds for thread milling with high-speed steel tools

Work material	Hardness, HB	Speed		Feed
		m/min	sfm	mm/tooth	in./tooth
Type 303	135-185	30	100	0.05	0.002
	225-275	27	90	0.04	0.0015

Nominal speeds for die cutting of screw threads

Work metal	Speed for pitch of
	≤ 7		8-15		16-24		≥ 25
	m/min	sfm	m/min	sfm	m/min	sfm	m/min	sfm
Types 303, 410, 420F, 440F	3	10	4.5	15	6	20	7.5	25

Nominal speed, cutting rate, and band life for the cutoff band sawing of steel bars

Steel being cut	Hardness, HB	Band speed		Cutting rates		Band life in terms of total area cut
		m/min	sfm	mm2 x 103/min	in.2/min	mm2 × 106	in.2 × 103
SS 303, 303F	150-200	40-27	130-90	3.2-1.3	5-2	2.1	3.3

Use & Application

SS303 is mainly used for parts that need machining, grinding or polishing, suitable for rapid cutting to make rolls, shafts, bolts, nuts, etc.

Equivalent

SS 303 stainless steel equivalent to European (German DIN, British BSI, France NF), Japanese JIS and Chinese GB standard (for reference).