1 Introduction
45 steel, widely known as S45C under JIS standard, equivalent to DIN C45 and AISI 1045 grade, is a versatile medium-carbon structural steel. With carbon content ranging 0.42-0.50 %, it delivers balanced strength, toughness and machinability, so it is heavily adopted for general mechanical components, mold base plates and moderate-load transmission parts worldwide.
Many procurement engineers and mold makers are confused: what is the actual price for 45 steel by thickness? What differences between hot-rolled plate and forged plate? And how much should you budget for CNC milling processing cost? This article answers those practical pain-points, combined with authoritative material data and heat-treatment guidance to support your material selection.
2 Core Chemical & Mechanical Properties of 45 Steel(S45C / AISI 1045)
2.1 Chemical Composition (Standard Specification, reference AZoM AISI 1045)
| Element | Carbon(C) | Silicon(Si) | Manganese(Mn) | Phosphorus(P) | Sulfur(S) | Iron(Fe) |
| Content | 0.42-0.50% | 0.17-0.37% | 0.60-0.90% | ≤0.040% | ≤0.050% | 98.51-98.98% |
2.2 Key Mechanical & Physical Performance
- Density: 7.87 g/cc
- Tensile strength: 570-700 MPa
- Yield strength: ≥310 MPa
- Elongation at break (50 mm gauge length): ≥16 %
- Annealed / normalized Brinell hardness: 170-210 HBW
- Quenched & tempered hardness: 280-320 HBW
- Elastic Modulus: 200 GPa
Major strengths of 45 steel:
- Good machinability under hot-rolled or normalized condition, suitable for cnc milling machine processing; tapping, drilling, turning and sawing can be completed with suitable cutting parameters. Its cutting time is 15-20 % less than high-alloy steel.
- Tunable performance via quenching and tempering to fit different load scenarios.
- Outstanding cost-performance among medium-carbon structural steels.
Important limitation: S45C / AISI1045 has poor through-hardening performance. The maximum section size for full through-hardening is around 60 mm. It can reach surface hardness HRC 54-60 by flame or induction hardening. Without alloying elements, nitriding treatment will not work for this steel grade.
3 45 Steel Price & Machining Cost Reference: Mainstream Specifications (2026 Reference)
3.1 Raw Material Price
Note: The prices below are our company’s reference market prices. Actual cost changes with order volume, surface requirement, tolerance standard and delivery term. Raw material price excludes tax and freight.
| Product Form | Thickness Range | Raw Material Unit Price (USD/kg) |
| Hot-rolled 45 steel plate | 10-100 mm | 0.61 |
3.2 CNC Machining Cost for 45 Steel
Machining cost mainly depends on part weight, complexity and tolerance requirements:
- For small-size parts: basic cutting and milling are charged on a per-piece basis.
- For heavy-weight parts: machining fees are calculated by weight.
- Extra charges will apply for heat treatment, tight tolerance, grinding or special surface finishing.
For customized quotations of 45 steel plates or pre-machined blanks, please visit our 45 steel product page for technical support.
4 Main Industrial Applications
45 steel accounts for over 40 % consumption of medium-carbon steel in general machinery manufacturing. Its typical usages cover gears, shafts, axles, bolts, crankshafts, spindles, guide rods and hydraulic fixture components：
- Mechanical transmission parts: 60 % general-purpose medium-load shafts, gears and connecting rods adopt 45 steel.
- Mold auxiliary components: mold base plates, guide pin blanks for plastic mould and stamping mould. It is widely used for non cavity mold structural parts.
- Automotive & engineering machinery: chassis components and moderate-load structural parts for commercial vehicles.
- General fixture and jig blanks for workshop tooling.
It is worth reminding: 45 steel is not fit for mold cavity core. It features poor corrosion resistance and limited polishing performance, so it should only be used for auxiliary mold structures.
5 Heat-Treatment Guidance for 45 Steel
Updated with AZoM technical parameters Proper heat-treatment greatly optimizes service life of 45 steel parts. Please follow temperature and holding-time rules based on workpiece thickness:
- Forging: Heat to 850-1250℃, hold for uniform temperature, furnace cool.
- Annealing: Heat to 800-850 °C, hold until temperature uniform, furnace cooling. Reduce hardness, eliminate internal stress from forging or rolling, improve machinability.
- Normalizing: Heat to 870-920℃, hold 10-15 min, cool in still air.
- Stress-Relieving: Heat to 550-660℃; soak 1 hour per 25 mm of section thickness, air cool.
- Hardening: Heat to 820-850 °C, soak 10-15 min per 25 mm section, quench in water or brine to achieve high hardness and wear resistance.
- Tempering: Re-heat to 400-650 °C as requirement, soak 1 hour per 25 mm section, air cooling, balance strength and toughness and avoid quenching brittleness.
5.1 Welding Notes for 45 Steel
45 steel can be welded with strict process control, but welding is not recommended for fully quenched-tempered or induction-hardened workpieces. Recommended welding procedure:
- Preheat workpiece to 200-300℃ before welding.
- Maintain pre-heating temperature during welding; select low-hydrogen welding electrodes.
- Slow cool using sand or ashes after welding.
- Complete stress-relieving heat-treatment afterwards to avoid cracking risk.
6 Our 45 Steel Solution
As a steel supplier with rich export experience, we supply hot-rolled plate, forged plate and round bar of 45 steel(S45C /AISI1045). Strict chemical composition inspection and MTC certificate are available for each batch.
We also provide one-stop service including cutting, CNC machining, rough milling, finish machining and heat-treatment. Our processing tolerance can reach ±0.02 mm for precision blanks, delivery cycle 3-7 working days for standard orders.
7 Conclusion
45 steel (S45C / AISI1045) remains the most cost-effective medium-carbon steel for general-purpose machinery. Before purchasing, confirm plate thickness, raw material form (hot-rolled / forged) and whether you need pre-machining service to control total project cost.
Notice its limitations on through-hardening depth, nitriding performance and welding of hardened parts during design phase.
Whether you need to purchase standard steel plates, custom processing parts, or technical support for material selection, our professional team can provide you with a full range of solutions. If you have any technical questions on 45 steel or quotation demand, feel free to contact our engineering team.
8. FAQ
Q1: Are 45 steel, S45C, C45 and AISI 1045 the same material?
A: Yes. They are equivalent grades under different standards: 45 steel(GB-China), S45C(JIS-Japan), C45(DIN-Germany), AISI 1045(AISI-USA). Chemical composition and mechanical properties are nearly identical and interchangeable for most engineering projects.
Q2: Can I use 45 steel for plastic mold cavity?
A: Not recommended. 45 steel has weak anti-corrosion capacity and limited polishing effect. It works well for mold base and auxiliary structure parts only.
Q3: What factors drive 45 steel price fluctuation?
A: Thickness (hot-rolled / forged), order quantity, tolerance requirement (light plate ±0.2 mm / precision plate ±0.1 mm) and additional processing (cutting, heat-treatment). Bulk order normally gets 10-15 % discount on raw material cost.
Q4: What is service life for 45 steel machined parts?
A: Under room-temperature moderate-load non-corrosive environment: 5-8 years without heat-treatment; after quenched-and-tempered process, service life extends to 8-12 years.
Q5: Should I choose hot-rolled plate or forged plate for my project?
A: Hot-rolled plate fits general mechanical parts with low-to-medium load, cost-saving. Forged plate has compact internal grain and fewer defects, better for heavy-load critical components even though the price is higher.
Q6: Can S45C / AISI1045 steel do nitriding treatment?
A: No. S45C / AISI1045 contains almost no alloying elements, nitriding cannot bring expected hardness improvement. If surface wear resistance is required, flame hardening or induction hardening is preferred. Its full through-hardening depth is limited to approximately 60 mm section size.
Q7: Is 45 steel easy to weld?
A: It can be welded with strict process: preheat to 200-300℃, adopt low-hydrogen electrodes and post-weld stress relief. Avoid welding workpieces which have been quenched-hardened, to prevent crack failure.