Description

Mild steel round bars are solid, long steel round bars with a carbon content between 0.10% and 0.30% and a circular cross-section. They belong to the basic profiles of ordinary carbon structural steel.

Mild steel round bars have a smooth, round surface without any texture. Their specifications are expressed in millimeters (mm) in diameter. They are manufactured in three ways: hot-rolled, cold-drawn steel round bar, and forged round steel bar. They are widely used in manufacturing parts that do not bear high stress but require high toughness.

Characteristics of Mild Steel Round Bars:

1. Excellent plasticity and toughness: The annealed microstructure is mainly ferrite with a small amount of pearlite, exhibiting extremely high ductility and good cold forming ability. It is suitable for edge rolling, bending, stamping, and other processing, and has a large deformation before fracture.

2. Excellent weldability: Due to its low carbon content and low carbon equivalent, mild steel round bars are less prone to cracking during welding. Various welding operations can be performed without complex preheating, making them the preferred material for building structural components and containers.

3. Low Strength and Hardness: Mild steel round bars typically have a tensile strength between 300-500 MPa, low hardness (generally ≤156 HBS), and poor wear resistance. They are usually used directly without heat treatment, or their surface hardness is improved through carburizing.

4. Moderate Machinability: The extremely low carbon content makes the material too soft, prone to tool sticking during cutting, and surface finish is difficult to control. Normalizing refines the grain size, improving machinability.

5. Cost and Economy: The production process is relatively simple, raw material costs are low, and the price is far lower than medium-high carbon round steel bars and alloy round steel bars, offering high cost-effectiveness.

Applications of Mild Steel Round Bars:

Mild steel round bars (typically with a carbon content below 0.25%) are mainly used in applications requiring moderate strength but good machinability due to their good plasticity, high toughness, excellent weldability, and cold formability.

1. Mechanical Fasteners and Standard Parts: Utilizing its excellent cold heading properties, Mild Steel Round Bar is widely used in the manufacture of bolts, nuts, rivets, chains, and various pins.

2. Automotive Manufacturing Parts: Mild Steel Round Bar is used to produce bearing cages, some body structural parts, and non-load-bearing mechanical parts; after carburizing treatment, it can also be used for mechanical parts requiring wear resistance.

3. Building and Engineering Structures: As ordinary carbon structural steel, it is widely used in building support columns, connectors, scaffolding, and bridge auxiliary components; after galvanizing, it can be used as grounding and lightning protection round steel.

4. Precision Machining and Tools: Some high-quality Mild Steel Round Bar, after heat treatment, can be used to manufacture cold extrusion punches, cold stamping dies, and small, high-life cutting tools.

5. Special Functional Components: Due to its good magnetic permeability, ultra-low carbon pure iron round steel is specifically used to manufacture electromagnetic components such as solenoid valve cores and relay cores.

Specifications of the Steel Round Bar:

Carbon Structural Steel Bright Round Bar	C10 C20 C35 C45 c55 St37-2 St37-3 St44-2 St44-3 St52-3	S10C S20C S25C S35C S45C S48C S50C S55C	1010 1020 1035 1045 1055	10# 20# 25# 35# 45# 20Mn 45Mn
Low – Alloy High – Strength Structural Steel Bright Round Bar	S235JR S235J0 S235J2 S275JR S275J0 S275J2 S355JR S355J0	S355J2 S275J0G3 S275J2G4 S355J2G3 S355J2G4 S355k2G3 S355K2G4 S355K2 S355J2G4	S275N S355N S355NL S420N S420NL S460N S460NL	Q355B Q355D Q390B Q390D
Alloy Structural Steel Bright Round Bar	20Mn2 30Mn2 40Mn2 20Cr 40Cr 15CrMo 20CrMo 30CrMo 42CrMo 41Cr4 16MnCr5 42CrMoS4	12Cr1MoV 20CrMnTi 20CrNiMo 40CrNiMo SAE1541 4120 4135 4140 4320 4340 8620H SCM415 SCM420	SCM430 SCM435 SCM440 SCr420 SCr420H SCr435 SCr440 34CrMo4 SNCM439 34Cr4	42CrMo4 39NiCrMo3 34CrNiMo6 18CrMo4 20NiCrMo2-2
Inconel Alloy Superalloys	Inconel601 InconeX750 Inconel600 Incoloy825 Inconel718	Incoloy800H Incoloy 800H Incoloy800 Inconel625 Inconel625 Inconel690	GH4099 GH128 GH145 GH169 GH605 GH3536 GH4033 GH99 GH625 GH4080AGH2132	GH132 GH500 GH600 GH536 GH4141 GH141 GH3625 GH2747 GH188 GH2696 GH747 GH3030

Diameter (mm)	Theoretical Weight (kg/m)	Diameter (mm)	Theoretical Weight (kg/m)
5.5	0.186	13	1.04
6	0.222	14	1.21
6.5	0.26	15	1.39
7	0.302	16	1.58
8	0.395	17	1.78
9	0.499	18	2
10	0.617	19	2.23
* 11	0.746	20	2.47
12	0.888	21	2.72
22	2.98	63	24.5
* 23	3.26	* 65	26
24	3.55	* 68	28.5
25	3.85	70	30.2
26	4.17	75	34.7
* 27	4.49	80	39.5
28	4.83	85	44.5
* 29	5.18	90	49.9
30	5.55	95	55.6
* 31	5.92	100	61.7
32	6.31	105	68
* 33	6.71	110	74.6
34	7.13	115	81.5
* 35	7.55	120	88.8
36	7.99	125	96.3
38	8.9	130	104
40	9.86	140	121
42	10.9	150	139
45	12.5	160	158
48	14.2	170	178
50	15.4	180	200
53	17.3	190	223
* 55	18.6	200	247
56	19.3	220	298
* 58	20.7	250	385
60	22.2

Products	Round Steel bar
Dia	5.5mm~650mm
Length	3m,6m,9m,12m
Standard	ASTM A 615 Gr 40/60,BSS4449 Gr460B,500B etc
Material	3Cr2Mo/1.2311/1.2312/P20/1.2738/718H/P20+Ni/1.2316/1.2083/4Cr13 /sus420j2/420/S136/NAK80H13/1.2344/SKD61/5CrNiMo/SKT4/1.2714 Cr12/D3/1.2080/Cr12MoV/D2/1.2379/SKD11/9CrWMn/O1/1.2510/SKS3 /DC53 40Cr/5140/35CrMo/42CrMo/4140/1.7225 C45/C50/1045/1050/S50C/S45C/T10/T8 M2/1.338/SKH51
Surface	ASTM，AISI，JIS，GB， DIN，EN
Technique	Hot rolled / cold rolled
Surface	Black Finish ,Oiled,Shot Blasted,Spray Paint,Coated,Galvanized,
Surface	Or as Your Request
Package	In bundle, no other package or wrapped with waterproof, or as customers’ requirement
Payment Term	T/T, L/C at sight,West Union,Paypal
Price Term	FOB,CRF,CIF,EXW all acceptable

S45C	0.42~0.48	0.60~0.90	0.15~0.35	≤0.03	≤0.03	≤0.20	≤0.20	≤0.30	_	_	JIS G4051-2005
S20C	0.18~0.23	0.30~0.60	0.15~0.35	≤0.03	≤0.035	≤0.20	≤0.20	≤0.30	_	_	JIS G4051-2005
ASTM A36	≤0.22	0.50~0.90	≤0.40	≤0.040	≤0.050	≤0.20	≤0.20	≤0.30	≥250	400~500	ASTM A36/A36M-03a
ASTM A105	≤0.35	0.6-1.05	≤0.35	≤0.050	≤0.040	≤0.20	≤0.20	≤0.30	≥310	485~620	ASTM A105/A105M
SAE1013	0.11~0.16	0.50~0.80	_	≤0.040	≤0.050	≤0.20	≤0.20	≤0.30	_	_	ASTM A568/A568M-91a
SAE1015	0.13~0.18	0.30~0.60	_	≤0.040	≤0.050	≤0.20	≤0.20	≤0.30	_	_
SAE1017	0.15~0.20	0.30~0.60	_	≤0.040	≤0.050	≤0.20	≤0.20	≤0.30	_	_
SAE1018	0.15~0.20	0.60~0.90	_	≤0.040	≤0.050	≤0.20	≤0.20	≤0.30	_	_
SAE1020	0.18~0.23	0.30~0.60	_	≤0.040	≤0.050	≤0.20	≤0.20	≤0.30	_	_
S235JR	0.15~0.20	≤1.4	_	≤0.035	≤0.035	≤0.20	_	_	≥235	400~510	EN10025
S275JR	≤0.22	≤1.4	_	≤0.035	≤0.035	≤0.20	_	_	≥275	490~610	EN10025
ST37-2	0.17~0.20	≤1.4	_	≤0.045	≤0.045	≤0.20	_	_	≥235