AISI 304L Round Bars

AISI 304L hot rolled round bar is the low carbon form of AISI 304, rolled for parts that are welded and cannot be annealed afterwards.

16 to 125 mm Austenitic stainless steel Made to order

HOT ROLLED ROUND BARS

AISI 304L hot rolled round bar

AISI 304L hot rolled round bar is the low carbon form of AISI 304, rolled to round section in diameters from 16 to 125 mm. Carbon is held to 0.03 percent maximum against 0.08 percent in standard 304. That lower limit slows sensitisation, the formation of chromium carbides along the grain boundaries during welding, which leaves the metal beside a weld open to attack. Bar welded in heavy section, or welded into an assembly too large to anneal afterwards, is therefore ordered in 304L rather than 304. Chromium and nickel sit at the same levels as in 304, so the two grades resist the same media. Where chlorides are present, the choice moves up to 316L, which carries molybdenum.

The bar is supplied solution annealed, a treatment that takes the carbides back into solution. In that condition the bar is non-magnetic, and it cannot be hardened by heat treatment, so higher strength comes only from cold work. ASTM A276 sets the annealed minima for 304L bar at 485 MPa tensile strength and 170 MPa yield strength. The grade welds without preheat and, in most sections, without a heat treatment afterwards. It work hardens under the tool, so machining calls for sharp edges and a feed that keeps the cut below the hardened skin. Laxcon Steels rolls it to order. Common work in this form is flanges and nozzles machined for welded vessels, pump shafts and valve stems, dairy and brewing plant parts, and bar the customer forges into fittings.

Composition limits in weight percent are carbon 0.03 maximum, manganese 2.0 maximum, sulphur 0.03 maximum, phosphorus 0.045 maximum, silicon 0.75 maximum, chromium 18.0 to 20.0, nickel 8.0 to 12.0 and nitrogen 0.1 maximum.

SPECIFICATION

AISI 304L 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 304 L (304L, SS 304L, SUS 304L, 1.4307)
Family: Austenitic stainless steel
Supply: Made to order in this grade; every published size of the form

Composition of AISI 304L

Element	Symbol	Minimum %	Maximum %
Carbon	C		0.03
Manganese	Mn		2.0
Sulphur	S		0.03
Phosphorus	P		0.045
Silicon	Si		0.75
Chromium	Cr	18.0	20.0
Nickel	Ni	8.0	12.0
Nitrogen	N		0.1

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

Equivalents of AISI 304L

Standard	Designation
UNS	S30403
EN number	1.4307 (X2CrNi18-9)
JIS	SUS 304L

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 304L runs from 18.0 at the specified minimum chromium, molybdenum and nitrogen to 21.6 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.
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 304L hot rolled round bar

An enquiry for this grade in this form states the grade and the governing standard, for example AISI 304L to ASTM A479 or EN 10088-3, the condition, the diameter with the tolerance class to ASTM A484 or EN 10060, the surface as black, spot ground or fully ground, the length, the quantity, and the test certificate type under EN 10204. Any test to be reported, such as ultrasonic testing or PMI confirmation of the grade, is named with it.