AISI 316 Round Bars

AISI 316 hot rolled round bar is a molybdenum-bearing austenitic bar for parts that work in chlorides, such as marine shafts and valve stems.

16 to 125 mm Austenitic stainless steel Made to order

HOT ROLLED ROUND BARS

AISI 316 hot rolled round bar

AISI 316 hot rolled round bar is an austenitic stainless bar rolled from a grade that carries 2 to 3 percent molybdenum beside its chromium and nickel. The molybdenum is the reason the grade exists: it slows pitting and crevice attack, the localised corrosion that chloride ions start in seawater, brine and many process liquors. AISI 304 holds no molybdenum and is the choice where the medium is fresh water, food or mild chemicals. Where chlorides are present and the bar must still be simple to machine and weld, 316 is the usual step up. Beside it sit AISI 316L, whose lower carbon protects a welded joint from attack at the grain boundaries, and duplex grades such as 2205, which give a higher yield strength.

The bar is supplied solution annealed: a soak above 1,000 degrees Celsius dissolves the chromium carbides and a fast cool keeps them dissolved. The annealed bar is non-magnetic, takes no hardening from heat treatment and gains strength only when it is cold worked; ASTM A276 puts its minima at 515 MPa tensile and 205 MPa yield. The grade work hardens under the tool, so turning it asks for a firm feed, sharp edges and lower speeds than carbon steel. It is welded without preheat. Round bar in this grade is machined into pump and valve shafts, marine fasteners, chemical plant fittings, and flanges and nozzles for process pipework.

Composition limits in weight percent are carbon 0.08 maximum, manganese 2.0 maximum, sulphur 0.03 maximum, phosphorus 0.045 maximum, silicon 0.75 maximum, chromium 16.0 to 18.0, nickel 10.0 to 14.0, molybdenum 2.0 to 3.0 and nitrogen 0.1 maximum.

SPECIFICATION

AISI 316 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 316 (316, SS 316, SUS 316, 1.4401)
Family: Austenitic stainless steel
Supply: Made to order in this grade; every published size of the form

Composition of AISI 316

Element	Symbol	Minimum %	Maximum %
Carbon	C		0.08
Manganese	Mn		2.0
Sulphur	S		0.03
Phosphorus	P		0.045
Silicon	Si		0.75
Chromium	Cr	16.0	18.0
Nickel	Ni	10.0	14.0
Molybdenum	Mo	2.0	3.0
Nitrogen	N		0.1

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

Equivalents of AISI 316

Standard	Designation
UNS	S31600
EN number	1.4401 (X5CrNiMo17-12-2)
JIS	SUS 316

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 316 runs from 22.6 at the specified minimum chromium, molybdenum and nitrogen to 29.5 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 316 hot rolled round bar

An enquiry for this grade in this form states the grade and the governing standard, for example AISI 316 to ASTM A479 or EN 10088-3, the condition as rolled, spot ground or fully ground, the diameter with the tolerance to ASTM A484 or EN 10060, the cut length, the quantity, the test certificate type to EN 10204, and any test called for, such as ultrasonic testing or PMI confirmation of the grade. Laxcon Steels rolls the bar to order.