1055 Steel | C55 |1.0535 | AISI 1055| S55C

1055 steel is an unalloyed medium carbon engineering steel which has 0.52%-0.6% Carbon as per EN10083 standard.It will obtain high hardness and high strength  after hardening due to the relatively high carbon content,and also can be flame or induction hardened to surface hardness Min 58HRC.C55 steel is generally supplied in an untreated or normalised condition.

1055 Steel Supply Form & Size & Tolerance

Hot Forged round bar:Φ130-Φ1000mm,Length:3000-10000mm

Flat bar/Blcoks:Thickness :120-800mm xWidth:120-1500mm,Length:2000-6000mm

Surface Finish	Black-Forged	Black-Rolled	Turned	Grinding	Polished	Peeled	Cold Drawn
Tolerance	(0，+5mm)	(0，+1mm)	(0，+3mm)	Best h9	Best h11	Best H11	Best H11

1055 Steel Chemical Composition

Grade	C	Mn	P	S	Si	Cr	Mo	Ni	Cr+Mo+Ni
C55/1.0535	0.52-0.6	0.60-0.90	≤ 0.045	≤ 0.045	≤ 0.4	≤ 0.4	≤ 0.1	≤ 0.4	≤ 0.63
C55E/1.1203	0.52-0.6	0.60-0.90	≤ 0.03	≤ 0.035	≤ 0.4	≤ 0.4	≤ 0.1	≤ 0.4	≤ 0.63
C55R/1.1209	0.52-0.6	0.60-0.90	≤ 0.03	0.02-0.04	≤ 0.4	≤ 0.4	≤ 0.1	≤ 0.4	≤ 0.63

1055 Steel Relevant Standards

USA	UK	China	Japan	Australia
1055	070M55 / EN9	55#	S55C	1055

1055 Steel Mechanical Property

Mechanical properties a at room temperature in the quenched and tempered condition (+QT)
Diameter d mm	≤ 16	16-40	40-100
Thickness t mm	< 8	8-20	20-60
Yield Strength Mpa	≥550	≥490	≥420
Tensile Strength Mpa	800-950	750-900	700-850
Elongation, %	≥12	≥14	≥15
Reduction of area ,%	≥30	≥45	≥40

Mechanical properties a at room temperature in the normalized condition (+N)
Diameter d mm	≤ 16	16-100	100-250
Thickness t mm	≤ 16	16-100	100-160
Yield Strength Mpa	≥370	≥330	≥300
Tensile Strength Mpa	≥680	≥640	≥620
Elongation, %	≥11	≥12	≥12

1055 Steel Forging

1055 steel forging temperature:900 – 1050°C ,cooling as slowly as possible in still air or in sand after forged.

1055 Steel Heat Treatment

• Normalizing:  825 – 885°C,Cooling in air
• Soft Annealing:650 – 700°C,Cooling in furnace
• Hardening:810 – 850°C,water or oil quench
• Tempering:550 – 660°C,Cooling in air

1055 Steel Surface Hardness

• Treated to improve shearability (+S):Max 255HB
• Soft annealed (+A):Max 229HB
• Flame or induction hardening:Min 58HRC

NORMAL HARDENABILITY +H (Hardness HRC – distance mm)
HRC – mm	1	2	3	4	5	6	7	8	9	10	11	13	15	20	25	30
MAX	65	64	63	62	60	57	52	45	37	36	35	34	33	32	30	29
MIN	58	55	47	37	33	32	31	30	29	28	27	26	25	24	22	20

1055 Steel Application

1055 steel is a medium carbon steel suitable for various type of applications where high strength is needed.It is used for components of small cross section requiring low tensile strength, and heavy forgings in the normalized condition for automotive and general engineering such as axles, clutch members, shafts, pressed and punched parts, piston rods and gear racks.