AISI 420 Round Bars

AISI 420 hot rolled round bar is a hardenable martensitic stainless bar used for valve stems, shafts and tooling.

16 to 125 mm Martensitic stainless steel Made to order

HOT ROLLED ROUND BARS

AISI 420 hot rolled round bar

AISI 420 hot rolled round bar is a martensitic stainless steel bar that is hardened by heat treatment rather than supplied at one fixed strength. The grade carries at least 0.15 percent carbon with 12 to 14 percent chromium, and that carbon is what separates it from AISI 410, which holds less of it and cannot reach the same hardness. Bar in 420 is chosen when a part has to hold an edge or resist wear and still be made from a stainless steel. Higher carbon grades such as 440C harden further, but 420 machines more easily and stays tougher in heavy sections, which suits shafts and spindles turned from bar of 16 to 125 mm diameter. The steel is magnetic in every condition.

The bar is normally supplied annealed, the soft condition in which it turns, drills and mills. Hardening follows machining: the part is heated to the austenitising temperature, quenched in oil or water and then tempered, and the tempering temperature sets the final hardness. Corrosion resistance is highest after hardening and tempering, because that treatment returns chromium to solution in the steel; in the annealed state much of the chromium sits in carbides instead. Welding is avoided where the design allows it, since the weld zone hardens and cracks unless the bar is preheated and tempered afterwards. Laxcon Steels rolls the bar to order, black, spot ground or fully ground, for valve stems and spindles, pump and mixer shafts, plastic mould tooling, and blanks for blades and shear knives.

Composition limits in weight percent are carbon 0.15 minimum, manganese 1.0 maximum, sulphur 0.03 maximum, phosphorus 0.04 maximum, silicon 1.0 maximum and chromium 12.0 to 14.0.

SPECIFICATION

AISI 420 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 420 (420, SUS 420J1, 1.4021, S42000)
Family: Martensitic stainless steel
Supply: Made to order in this grade; every published size of the form

Composition of AISI 420

Element	Symbol	Minimum %	Maximum %
Carbon	C	0.15
Manganese	Mn		1.0
Sulphur	S		0.03
Phosphorus	P		0.04
Silicon	Si		1.0
Chromium	Cr	12.0	14.0

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

Equivalents of AISI 420

Standard	Designation
UNS	S42000
EN number	1.4021 (X20Cr13)
JIS	SUS 420J1

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 420 hot rolled round bar

An enquiry for this grade names the grade and the governing standard, EN 10088-3 or ASTM A276, the condition wanted, annealed or hardened and tempered, the diameter with the tolerance class to ASTM A484 or EN 10060, the finish, the cut length within 8 metres, the quantity, the inspection document to EN 10204, and any ultrasonic test or PMI check required.