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1045 C45 S45C Carbon Steel

S45C tool steel boasts balanced strength and toughness, great machinability and cost efficiency, perfectly suited for mold bases, support plates, drive shafts, medium-duty gears and construction machinery structural parts.

Standard: AISI 1045, DIN C45, JIS S45C, GB 45#
Technique: EAF + LF + VD, forged or hotrolled, multidirectional forging ratio ≥4, normalized or annealed as required
Shape: Round, Flat, Plates, Blocks
Heat treatment: Supplied in normalized condition, hardness ≤229 HBW typical; quenched and tempered (QT) to 22–30 HRC available on request
Surface Treatment: Turned, milled / ground, sawn ends. Black (hotrolled / forged surface) available for large sections
Tolerance: flat bars & plates thickness: +0.5/-0.0 mm (turned); forged blocks: ±0.2 mm
MOQ: 1 Ton

We supply AISI 1045 in various custom sizes

Chemical Composition (%)

Grade	C	Si	Mn	P (≤)	S (≤)
1045	0.43–0.50	0.15–0.35	0.60–0.90	0.035	0.040
C45	0.42–0.50	≤0.40	0.50–0.80	0.030	0.035
S45C	0.42–0.48	0.15–0.35	0.60–0.90	0.030	0.030
45 (45#)	0.42–0.50	0.17–0.37	0.50–0.80	0.030	0.030

Main characteristics of S45C tool steel

1045 | C45 | S45C tool steel applications

S45C steel for Mold Base & Support Plate

Excellent machinability and consistent strength make S45C the standard, cost-efficient choice for mold bases, die sets, and bolster plates.

S45C steel for Drive Shaft & Medium-Duty Gear

Good balance of strength and toughness after induction hardening provides reliable wear resistance and fatigue life for shafts and gears in general machinery.

S45C steel for Construction Machinery Structural Part

Easy weldability combined with adequate yield strength allows S45C to be fabricated into robust, durable structural components for heavy equipment.

Our Production Technology For S45C (AISI 1045 / DIN C45) Medium Carbon Structural Steel

EAF
LF
VD
Fully Killed Steel
Hot Rolled or Hot Extruded
Forged (as required)
Annealed / Normalized / Quenched and Tempered (as specified)
Black surface or Machined surface / Peeled

mechanical properties & heat treatment of S45C steel

Heat temperature	Start forging temperature	Finish forging temperature	Cooling method
1150 – 1200 °C	1050 – 1000 °C	≥ 850 °C	Pit, sand, or furnace cooling

Annealing

Annealing temperature: 810 – 860°C
Hold at temperature for sufficient time (minimum 1 hour per 25mm of section thickness)
Cool slowly in the furnace
Hardness after annealing: ≤ 197 HB
Annealing in a protective atmosphere is recommended to reduce decarburization and surface scaling

Hardening

S45C is a medium carbon steel with poor hardenability. Quenching can cause deformation and cracking, making heat treatment control critical. Quenching is typically performed in water for maximum hardness
Pre-heating (recommended): Preheat to 600 – 650°C to reduce thermal shock during austenitizing
Austenitizing temperature: 820 – 870°C.
Lower range (820–840°C): For thinner sections and complex shapes
Upper range (840–870°C): For heavier sections
Holding time: At least 30 minutes per 25mm of section thickness
Quenching media:
Water (preferred) — provides maximum hardness but increases distortion and crack risk
Oil — for reduced distortion, but lower hardness
Polymer — medium quench rate, good for distortion control
Hardness after quenching (before tempering) : > 55 HRC (up to 62 HRC maximum)

Stress relieving

Perform after rough machining, heavy stock removal, or welding to reduce residual stresses
Heat carefully to 600 – 650°C (below the tempering temperature)
Hold at temperature for 1 hour per 25mm of section thickness (minimum 2 hours)
Air cool after holding
This operation reduces the risk of distortion during final heat treatment and improves dimensional stability

Tempering

Temper immediately after quenching when the workpiece cools to hand-warm temperature (approx. 50–70°C). Delayed tempering may cause cracking
Number of tempers: Minimum 1 time for standard applications; 2 times recommended for critical components
Holding time: 1 hour per 25mm of section thickness (minimum 2 hours)
Cooling method: Rapid cooling (out-of-furnace quenching) is required after tempering to avoid temper brittleness. S45C does not exhibit secondary temper brittleness, but rapid cooling is recommended
Tempering temperature range: 550 – 650°C

Normalizing

Normalizing temperature: 840 – 880°C
Hold at temperature until uniformly heated (approx. 30 minutes per 25mm of section thickness)
Cool in still air
Hardness after normalizing: 167 – 229 HB
Purpose: Refine grain structure, eliminate forging stresses, and prepare for final heat treatment

Why Choose NSPM as Your S45C Tool Steel Supplier

Source Direct

Direct mill cooperation ensures stable supply, competitive pricing, and consistent quality. Global resource integration and strong supply chain management guarantee reliable material sourcing and long-term availability.

Stock Ready

50,000+ tons inventory across 11 warehouses enables fast delivery. Flexible cutting, short lead times, and ready stock support urgent demands and improve customers’ production efficiency.

Expert Team

600+ professionals, including R&D specialists and technical engineers, provide application-driven support. Fast response and deep tooling knowledge ensure accurate solutions for diverse industrial needs.

Fully Inspected

Strict quality control system with full traceability, UT testing, and heat treatment records. Certified standards (ISO, CE) ensure every material meets high-performance and reliability requirements.

Full-Chain Machining

From steel supply to precision machining, heat treatment, and equipment manufacturing, NSPM offers integrated solutions that enhance accuracy, efficiency, and overall tooling performance.