🟦 Product Overview

4130, 4140, and 4340 Alloy Steel Bars belong to the Chromium‑Molybdenum (Cr‑Mo) and Nickel‑Chromium‑Molybdenum (Ni‑Cr‑Mo) family, widely used for:

• High‑strength mechanical components
• Automotive and aerospace parts
• Shafts, gears, and fasteners
• Oil & gas equipment
• Heavy machinery

These alloy steels offer:

• High tensile strength
• Excellent toughness
• Good fatigue resistance
• Superior hardenability
• Excellent performance after heat treatment (Q+T)

They are the most commonly used alloy steel grades in global engineering and manufacturing.

🟦 Standards

• ASTM A29
• ASTM A322
• ASTM A108
• JIS / DIN / GB equivalents available

🟦 Grades Included

• 4130 — Cr‑Mo alloy steel with excellent toughness
• 4140 — Most widely used alloy steel, high strength + good machinability
• 4340 — Ni‑Cr‑Mo alloy steel with ultra‑high strength and fatigue resistance

🟦 Product Specifications & Available Sizes

Shapes Available

• Round Bar
• Square Bar
• Flat Bar
• Hex Bar

Diameter Range

• 10–800 mm

Length

• 1–12 m / custom cut

Surface Conditions

• Hot Rolled
• Cold Drawn
• Peeled / Turned
• Polished
• Quenched & Tempered (Q+T)

🟦 Chemical Composition Comparison

Grade	C (%)	Mn (%)	Si (%)	Cr (%)	Mo (%)	Ni (%)
4130	0.28–0.33	0.40–0.60	0.15–0.35	0.80–1.10	0.15–0.25	—
4140	0.38–0.43	0.75–1.00	0.15–0.35	0.80–1.10	0.15–0.25	—
4340	0.38–0.43	0.60–0.80	0.15–0.35	0.70–0.90	0.20–0.30	1.65–2.00

🟦 Mechanical Properties Comparison（As Rolled）

Grade	Tensile Strength	Yield Strength	Hardness
4130	560–670 MPa	435 MPa	197 HB
4140	655–850 MPa	415–540 MPa	197–235 HB
4340	745–930 MPa	470–600 MPa	217–255 HB

🟦 Mechanical Properties（After Q+T Heat Treatment）

Grade	Tensile Strength	Yield Strength	Hardness
4130 Q+T	850–1000 MPa	650–750 MPa	240–280 HB
4140 Q+T	950–1100 MPa	700–850 MPa	260–300 HB
4340 Q+T	1080–1400 MPa	850–1100 MPa	280–340 HB

🟦 Physical Properties

Property	Value
Density	7.85 g/cm³
Melting Point	~1425–1500°C
Magnetic	Yes

🟦 Manufacturing Processes

• Hot Rolling
• Cold Drawing
• Turning / Peeling
• Grinding / Polishing
• Quenching & Tempering (Q+T)
• Straightening
• Ultrasonic Testing

🟦 Primary Industry Usage

• Automotive & aerospace components
• Shafts, axles, gears
• Oil & gas equipment
• Heavy machinery
• High‑strength fasteners
• Power transmission parts

🟦 Why Use Alloy Steel Bar

• High strength + toughness
• Excellent fatigue resistance
• Good hardenability
• Ideal for heat‑treated mechanical parts
• Suitable for high‑load applications

🟦 Why Choose WelSteels

• Full range of 4130 / 4140 / 4340
• Hot rolled, cold drawn, and Q+T options
• MTC 3.1 + third‑party inspection
• Export‑grade packaging
• Competitive pricing for global buyers

International Carbon Steel Grade

America	Japan	Germany		Britain		France	Italy	Spain	Switzerland	China
AISI/SAE	JIS	W‐nr.	DIN	BS	EN	AFNOR	UNI	UNE	SS	GB
A570.36	STKM 12A	1.0038	RSt.37‐2	4360	‐	E 24‐2	‐	‐	1311	15
–	STKM 12C	–	–	40 C	–	Ne	–	–	–	–
1015	‐	1.0401	C15	080M15	‐	CC12	C15, C16	F.111	1350	15
1020	‐	1.0402	C22	050A20	2C	CC20	C20, C21	F.112	1450	20
1213	SUM22	1.0715	9SMn28	230M07	1A	S250	CF9SMn28	F.2111	1912	Y15
								11SMn28
12L13	SUM22L	1.0718	9SMnPb28	‐	‐	S250Pb	CF9SMnPb28	11SMnPb28	1914	‐
‐	‐	1.0722	10SPb20	‐	‐	10PbF2	CF10Pb20	10SPb20	‐	‐
1215	‐	1.0736	9SMn36	240M07	1B	S300	CF9SMn36	12SMn35	‐	Y13
12L14	‐	1.0737	9SMnPb36	‐	‐	S300PB	CF9SMnPb36	12SMnP35	1926	‐
1015	S15C	1.1141	Ck15	080M15	32C	XC12	C16	C15K	1370	15
1025	S25C	1.1158	Ck25	‐	‐	‐	‐	‐	‐	25
A572-60	‐	1.890	StE380	4360 55	‐	‐	FeE390KG	‐	2145	‐
1035	‐	1.0501	C35	060A35	‐	CC35	C35	F.113	1550	35
1045	‐	1.0503	C45	080M46	‐	CC45	C45	F.114	1650	45
1140	‐	1.0726	35S20	212M36	8M	35MF4	‐	F210G	1957	‐
1039	‐	1.1157	40Mn4	150M36	15	35M5	‐	‐	‐	40Mn
1335	SMn438(H)	1.1167	36Mn5	‐	‐	40M5	‐	36Mn5	2120	35Mn2
1330	SCMn1	1.1170	28Mn6	150M28	14A	20M5	C28Mn	‐	‐	30Mn
1035	S35C	1.1183	Cf35	060A35	‐	XC38TS	C36	‐	1572	35Mn
1045	S45C	1.1191	Ck45	080M46	‐	XC42	C45	C45K	1672	Ck45
1050	S50C	1.1213	Cf53	060A52	‐	XC48TS	C53	‐	1674	50
1055	‐	1.0535	C55	070M55	9	‐	C55	‐	1655	55
1060	‐	1.0601	C60	080A62	43D	CC55	C60	‐	‐	60
1055	S55C	1.1203	Ck55	070M55	‐	XC55	C50	C55K	‐	55
1060	S58C	1.1221	Ck60	080A62	43D	XC60	C60	‐	1678	60Mn
1095	‐	1.1274	Ck101	060A96	‐	XC100	‐	F.5117	1870	‐
W1	SK3	1.1545	C105W1	BW1A	‐	Y105	C36KU	F.5118	1880	‐
W210	SUP4	1.1545	C105W1	BW2	‐	Y120	C120KU	F.515	2900	‐