AISI 431 Round Bars

AISI 431 hot rolled round bar is a nickel bearing martensitic stainless bar used for shafts, valve parts and marine bolting.

16 to 125 mm Martensitic stainless steel Made to order

HOT ROLLED ROUND BARS

AISI 431 hot rolled round bar

AISI 431 hot rolled round bar is a martensitic stainless steel hot rolled to round section, in diameters from 16 to 125 mm. The grade carries 15 to 17 percent chromium with 1.25 to 2.5 percent nickel, more chromium than AISI 410 and an addition of nickel that 410 does not have. That pairing is why it is specified: it reaches a higher strength after hardening and tempering than 410, and it holds up better in damp air and mild chloride service. Against AISI 420, which carries more carbon, 431 gives up peak hardness and gains toughness and corrosion resistance, so it suits loaded parts rather than cutting edges. The grade is also written 1.4057, SUS 431 and UNS S43100. Laxcon Steels rolls the bar to order.

The bar leaves the mill black as rolled, spot ground or fully ground, in lengths up to 8 metres. It is normally supplied annealed, the soft condition in which the steel machines and drills without trouble, and it is hardened afterwards by austenitising, quenching in oil or water and tempering to the strength the finished part needs. The steel is magnetic in every condition. Welding is awkward, because the weld zone hardens as it cools, so a joint needs preheat and a temper after welding. Work in this form runs to pump and compressor shafts, valve stems and spindles, marine and oilfield bolting, and gear and coupling blanks that the customer machines or forges to shape.

Composition limits in weight percent are carbon 0.2 maximum, manganese 1.0 maximum, sulphur 0.03 maximum, phosphorus 0.04 maximum, silicon 1.0 maximum, chromium 15.0 to 17.0 and nickel 1.25 to 2.5.

SPECIFICATION

AISI 431 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: Soft annealing; oil or water quenching and tempering
Grade: AISI 431 (431, SUS 431, 1.4057, S43100)
Family: Martensitic stainless steel
Supply: Made to order in this grade; every published size of the form

Composition of AISI 431

Element	Symbol	Minimum %	Maximum %
Carbon	C		0.2
Manganese	Mn		1.0
Sulphur	S		0.03
Phosphorus	P		0.04
Silicon	Si		1.0
Chromium	Cr	15.0	17.0
Nickel	Ni	1.25	2.5

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

Equivalents of AISI 431

Standard	Designation
UNS	S43100
EN number	1.4057 (X17CrNi16-2)
JIS	SUS 431

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.

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 431 hot rolled round bar

An enquiry for this grade states the grade and governing standard, AISI 431 to ASTM A276 or 1.4057 to EN 10088-3, the condition, annealed or hardened and tempered to an agreed strength, the diameter with the tolerance class to ASTM A484 or EN 10060, the length, the surface, black, spot ground or fully ground, the quantity, the test certificate type to EN 10204, and any ultrasonic test or PMI check required.