AISI 1045 Steel Bar | ASTM 1045 Carbon Steel

AISI 1045 steel is a widely used medium-carbon, high-quality carbon structural steel under the AISI/ASTM standard system.

AISI 1045 steel is a versatile medium-carbon steel known for its balanced strength, toughness, and machinability. It offers good forging properties and can be effectively heat-treated to meet specific mechanical requirements.

Supported by mature production processes and strong cost-effectiveness, it is widely used to manufacture durable, medium-load components such as shafts, gears, and connecting rods, making it a fundamental material in machinery manufacturing and equipment industries.

AISI 1045 STEEL & EQUIVALENT GRADE CHEMICAL COMPOSITION

Grade	C	Si	Mn	P	S	Cr
1045	0.43-0.50	0.15-0.35	0.60-0.90	≤0.04	≤0.05	-
45#	0.42-0.50	0.17-0.37	0.50-0.80	≤0.035	≤0.035	≤0.25
C45	0.42-0.50	≤0.4	0.50-0.90	≤0.03	≤0.035	≤0.4
S45C	0.42-0.48	0.15-0.35	0.60-0.90	≤0.03	≤0.035	-

AISI 1045 STEEL PHYSICAL PROPERTY

Density, g/cm3	7.85
Melting point °C	1430-1450
Poisson's ratio	0.29-0.30
Modulus of Elasticity, Gpa	190-210
Linear expansion coefficient (20-100℃)	11.7×10⁻⁶ /℃
Thermal conductivity W/(m.K)	48-51
Specific heat capacity (20℃),J/(kg・K)	Approx. 460
Resistivity,Ω・m	0.15-0.18

AISI 1045 STEEL FORGING

As a medium-carbon structural steel, AISI 1045 steel has good hot forging properties and strong deformation capacity. The core points of its forging process are as follows:

Preheating	Initial forging temperature	Final forging temperature	Forging ratio	Cooling method
600-700°C	1100-1200°C	≥800℃	≥4:1	Slow cooling

It should be noted here that 1045 steel can be air-cooled when necessary to achieve a certain effect of refining the grains, but it should never be cooled rapidly.

AISI 1045 STEEL HEAT TREATMENT

To achieve the desired strength, hardness, toughness, and wear resistance, AISI 1045 steel can be processed using various heat treatment techniques.

AISI 1045 Steel Normalizing

The normalizing process for AISI 1045 steel focuses on improving its microstructure and strength. It can be used as a pretreatment process before quenching and tempering, or as the final heat treatment process for parts with low performance requirements.Therefore, normalizing is widely used in 1045 steel.

Temperature	Cooling method	Process time	Microstructure	Grain size
850-880°C	Air cooling	2-3 days	Fine pearlite+ferrite	6-8

AISI 1045+N Mechanical Property

Tensile Strength	Yield Strength	Elongation	Reduction of Area	Impact Charpy-V	Hardness
670-720 Mpa	≥340 Mpa	15-18%	45-50%	≥50 J	170-240 HBW

AISI 1045 Steel Annealing

The annealing process for AISI 1045 steel focuses on reducing hardness to facilitate machining.It mainly includes soften annealing and stress-relief annealing.

Soften Annealing	Stress-relief Annealing
780-820°C	550-650°C

The difference between the two is that stress-relief annealing does not change the original microstructure and hardness, while soften annealing gives 1045 steel a coarse lamellar pearlite and ferrite microstructure, with a hardness of less than 200 HBW.

AISI 1045 Steel Quenching & Tempering

This is the core heat treatment process for 1045 steel, the purpose of which is to obtain good comprehensive mechanical properties.

AISI 1045 Quenching Process
Temperature	Cooling method	Microstructure	Hardness
830-850°C	Water cooling	Martensite+Retained Austenite	55-60HRC

Tempering should be performed as soon as possible after quenching!

AISI 1045 steel can be adjusted according to the tempering temperature to obtain the required strength, hardness, and toughness.

High-temperature tempering	Medium temperature tempering	Low-temperature tempering
550-650℃	350-500℃	150-250℃
20-30HRC	33-38HRC	55-60HRC
High-performance parts	Elastic parts	High wear-resistant parts

AISI 1045+QT Mechanical Property

Section Size mm	≤ 16	17 - 40	41 - 100
Tensile Strength Mpa	700-850	650-800	630-780
Yield Strength Mpa	≥ 500	≥430	≥ 370
Elongation %	≥ 14	≥ 16	≥ 17
Impact Charpy J	≥ 30	≥ 30	≥ 30
Hardness HB	210-245	195-235	185-230

AISI 1045 STEEL SUPPLY FORM & SIZE & TOLERANCE

If you are in search of premium AISI 1045 steel for your business operations, FUHONG stands as your ideal partner. We rank among China’s leading suppliers, with a dedicated focus on delivering high-quality, dependable and efficient 1045 steel products. No production challenge is insurmountable with our advanced processing technology, which is engineered to fulfill all your production demands.

Contact us today to explore our core 1045 steel solutions, and let FUHONG assist you in upgrading your products and enhancing your market competitiveness.

AISI 1045 steel Supplier,Stockist and Exporter,supplied with Round,Square,Flat,Block,and Shaft etc.

Hot Forged Round bar:Φ80-Φ1500mm

Hot Rolled Round bar:Φ14-Φ350mm

Hot Forged Square bar: Max Thickness:500mm

Flat bar/Blcoks:Thickness :120-800mm ,Width:120-1500mm

Surface Finish	Black-Forged	Black-Rolled	Rough Turned	Cold Drawn	Peeled	Polished	Grinded
Tolerance	0/+5mm	0/+1mm	0/+3mm	Best H11	Best H9	Best H9	Best h8

Heat treatment:Quenched and Tempered (+QT), Normalizing (+N), Annealing (+A)

RFQ AISI 1045 steel

FREQUENTLY ASKED QUESTIONS FOR AISI 1045 STEEL

Does 1045 steel rust?admin2026-10-05T09:24:36+08:00

Does 1045 steel rust?

Yes. 1045 steel has no chromium or other alloying elements for corrosion resistance. Protect it with oil, plating, phosphating, or paint to suit the service environment.

Can 1045 steel be hardened?admin2026-10-05T09:23:51+08:00

Can 1045 steel be hardened?

Yes. Thin sections harden by water quench to roughly 50 – 55 HRC. The common production route for machine parts is induction or flame hardening of the surface to 54 – 60 HRC, which leaves a tough core.

Which is stronger, 1045 or 4140?admin2026-10-05T09:22:34+08:00

Which is stronger, 1045 or 4140?

4140 hardens deeper and carries more toughness. 1045 wins on material cost and machinability. The question is not which grade is better, but what the duty requires.

Is 1045 steel good for shafts?admin2026-10-05T09:20:15+08:00

Is 1045 steel good for shafts?

For moderate-duty shafts, yes.1045 steel is one of the most common plain-carbon shaft materials in machinery. For high speed, high cyclic load, or heavy shock, move to an alloy grade such as 4140.

What hardness does 1045 reach in different conditions?admin2026-10-05T09:18:57+08:00

What hardness does 1045 reach in different conditions?

As rolled 1045 steel runs about 170 – 210 HB, annealed about 150 – 190 HB. Quenched, thin sections can reach about 50 – 55 HRC, and tempered parts typically run at 25 – 35 HRC.

Is AISI 1045 the same as C45, S45C, or EN8?admin2026-10-05T09:16:43+08:00

Is AISI 1045 the same as C45, S45C, or EN8?

They are equivalent grades under different standards: SAE/ASTM 1045, JIS S45C, DIN/EN C45 (1.1191), BS EN8 (080M40), and GB 45. Chemistry and typical properties are close, but each standard sets its own tolerances and supply conditions. Always verify before substituting one for another.

Can 1045 steel be quenched to any size?admin2026-09-09T14:20:05+08:00

Can 1045 steel be quenched to any size?

This is the most common and most costly mistake. Without alloying elements to slow the cooling rate, 1045 only through-hardens in relatively thin sections,roughly 25 mm or less.

If you need through-hardening in large sections, you need an alloy steel like 4140 or 4340. For surface wear on large parts, induction hardening 1045 is the right answer,but it is not the same as through-hardening.

Is a higher carbon content always better for carbon steel?admin2026-09-09T14:17:23+08:00

Is a higher carbon content always better for carbon steel?

More carbon means more potential hardness, but it also means less ductility, worse weldability, and higher risk of cracking during heat treatment.

A 1095 steel knife blade holds a great edge, but you wouldn’t use it to make crankshafts because it would shock under impact.1045 steel has a carbon content of 0.45%, as this is the optimal ratio for general-purpose mechanical parts.

Is 1045 steel a cheap steel?admin2026-09-09T14:10:16+08:00

Is 1045 steel a cheap steel?

It is inexpensive relative to alloy steels, but that does not make it low-quality.

1045 is a fully-killed, fine-grain steel with consistent chemistry and predictable heat-treatment response. Its low cost comes from the absence of expensive alloying elements, not from corner-cutting in manufacturing.

If a part only needs medium strength, paying for chromium and molybdenum is wasteful, not sophisticated.