AISI 303 Round Bars

AISI 303 hot rolled round bar is a free-machining austenitic stainless steel bar for parts turned in volume.

16 to 125 mm Austenitic stainless steel Made to order

HOT ROLLED ROUND BARS

AISI 303 hot rolled round bar

AISI 303 hot rolled round bar is an austenitic stainless steel bar rolled from steel to which sulphur has been added deliberately. The sulphur forms manganese sulphide inclusions spread through the metal, and these break the chip as the tool cuts, so the bar can be turned, drilled and threaded at higher speed than AISI 304 and the swarf clears instead of winding round the tool. Chromium and nickel sit close to the levels in AISI 304, so the two bars look alike, but the inclusions are also where pitting starts. AISI 304 is the grade for a part that must resist corrosion or be welded. AISI 303 is the grade for a part cut from solid in quantity where the service is mild and dry.

The bar is supplied solution annealed, which puts the alloying elements into solution and leaves the structure austenitic and non-magnetic. Heat treatment cannot harden it, and strength is raised only by cold work, which a part cut on a lathe does not receive. Welding is avoided, because the sulphur makes weld metal crack as it cools; a part that has to be joined is usually made in AISI 304 instead. Laxcon Steels rolls the bar to order from 16 to 125 mm diameter, black as rolled, spot ground or fully ground, ultrasonically tested and grade checked by handheld PMI. Work commonly turned from it includes shafts and spindles, bushes and bearing sleeves, valve and pump parts, and nuts, bolts and other machined fasteners.

Composition limits in weight percent are carbon 0.15 maximum, manganese 2.0 maximum, sulphur 0.15 minimum, phosphorus 0.2 maximum, silicon 1.0 maximum, chromium 17.0 to 19.0, nickel 8.0 to 10.0 and zirconium plus molybdenum 0.6 maximum.

SPECIFICATION

AISI 303 hot rolled round bar supply conditions

Size range: 16 mm - 125 mm (5/8" - 5")
Length: Up to 8 metres
Tolerances: ASTM A484, EN10060
Heat treatment: Solution annealing
Grade: AISI 303 (303, SUS 303, 1.4305, S30300)
Family: Austenitic stainless steel
Supply: Made to order in this grade; every published size of the form

Composition of AISI 303

Element	Symbol	Minimum %	Maximum %
Carbon	C		0.15
Manganese	Mn		2.0
Sulphur	S	0.15
Phosphorus	P		0.2
Silicon	Si		1.0
Chromium	Cr	17.0	19.0
Nickel	Ni	8.0	10.0
Zirconium plus molybdenum	Zr+Mo		0.6

Composition, weight percent, balance iron. From the Laxcon Steels grade reference.

Equivalents of AISI 303

Standard	Designation
UNS	S30300
EN number	1.4305 (X8CrNiS18-9)
JIS	SUS 303

Equivalence means nearest counterpart, not identity: each standards body sets its own composition window, so the limits of the standard named on the order govern.

Pitting resistance

The pitting resistance equivalent number of AISI 303 runs from 17.0 at the specified minimum chromium, molybdenum and nitrogen to 19.0 at the maxima, computed as PREN = Cr + 3.3Mo + 16N (International Molybdenum Association). It ranks resistance to chloride pitting against other austenitic and duplex grades and nothing else: it does not predict crevice corrosion, stress corrosion cracking or service life. The pitting resistance reference carries the full table.

Governing standards

EN 10088-3: Stainless steels: technical delivery conditions for semi-finished products, bars, rods, wire, sections and bright products for general purposes. Composition, heat treatment condition and mechanical properties per grade.
EN 10060: Hot rolled round steel bars for general purposes: dimensions and tolerances on shape and dimensions.
ASTM A276/A276M: Stainless steel bars and shapes: composition, condition, mechanical properties and finish designations for hot-finished and cold-finished bar.
ASTM A484/A484M: General requirements for stainless steel bars, billets and forgings: permissible variations in dimensions, straightness, weight and length, and the test and marking requirements every bar order inherits.
ASTM A479/A479M: Stainless steel bars and shapes for use in boilers and other pressure vessels: the bar specification a pressure-part drawing calls for.
ASTM A314: Stainless steel billets and bars for forging.
NACE MR0175 / ISO 15156: Materials for use in H2S-containing environments in oil and gas production: the sour-service limits on hardness and condition.
ASTM A582/A582M: Free-machining stainless steel bars: the specification under which 303 and the other resulphurised grades are supplied.
EN 10204: Metallic products, types of inspection documents: the 2.2 test report and the 3.1 and 3.2 inspection certificates a purchase order can call for.

Weight per metre

Diameter (mm)	kg per metre	Metres per tonne
16	1.59	629.5
17	1.79	557.6
18	2.01	497.4
19	2.24	446.4
20	2.48	402.9
21	2.74	365.4
22	3.00	333.0
23.2	3.34	299.4
24	3.57	279.8
25	3.88	257.9
26	4.19	238.4
27	4.52	221.1
28	4.86	205.6
30	5.58	179.1
32	6.35	157.4
34	7.17	139.4
36	8.04	124.4
37	8.49	117.7
38	8.96	111.6
40	9.93	100.7
42	10.95	91.4
45	12.57	79.6
47	13.71	73.0
48	14.30	69.9
50	15.51	64.5
53	17.43	57.4
56	19.46	51.4
57.5	20.52	48.7
60	22.34	44.8
63	24.63	40.6
66	27.03	37.0
67.5	28.27	35.4
70	30.40	32.9
73.5	33.52	29.8
75	34.90	28.7
77.5	37.27	26.8
80	39.71	25.2
83	42.75	23.4
85	44.83	22.3
88	48.05	20.8
90	50.26	19.9
93	53.67	18.6
95	56.00	17.9
98	59.59	16.8
100	62.05	16.1
105	68.41	14.6
106	69.72	14.3
110	75.08	13.3
115	82.06	12.2
120	89.35	11.2
125	96.95	10.3

Density 7.90 g/cm³, diameter squared x 0.006205. Sizes are the published range at the nominal diameters shown.

Ordering AISI 303 hot rolled round bar

An enquiry for this grade in this form names the grade and the governing standard, EN 10088-3 for 1.4305 or the ASTM specification in use, the delivery condition, the diameter with the tolerance class to ASTM A484 or EN 10060, the surface, the cut length within 8 metres, the quantity, the inspection document to EN 10204, and any ultrasonic test or PMI check required.