Top 10 Steel Choices for CNC Machining and Performance

Selecting the right steel is crucial for achieving top-notch machining performance and durability. This blog explores various high-performance steels like 45 Steel, 40Cr Steel, T10 Steel, and others. We’ll highlight their key properties, applications, and benefits to help engineers and procurement professionals make informed decisions. Dive in to discover how these steel choices can enhance your projects.


45 Steel

45 steel is referred to as GB in China, commonly with HRC: 35~40, and surface oxidation treatment. In JIS, it is known as S45C, in ASTM as 1045, 080M46, and in DIN as C45. 45 steel is a high-quality carbon structural steel with moderate hardness and is easy to machine, often used for making molds, guides, and bushes. However, it requires heat treatment.

  • Applications: Primarily used for mechanical manufacturing, 45 steel offers excellent mechanical properties. Although it is a medium-carbon steel, its quenching properties are not optimal. The tempering hardness of 45 steel ranges from HRC42 to 46. For applications requiring high surface hardness and good mechanical properties, surface quenching is applied to achieve the necessary hardness.
  • Characteristics: Post-tempering hardness is HRC42-45, prone to cracking, with noticeable reduction in mechanical properties. It is typically safe within HRC40-45. For higher hardness requirements, material replacement is advisable.
  • Untempered Hardness: HRC28, which is relatively soft and not wear-resistant; post-quenching hardness can exceed HRC55, providing better wear resistance.
  1. The untreated hardness of 45 steel is less than HRC55 (maximum HRC62).
  2. The commonly used maximum hardness is HRC55 (high-carbon steel can reach HRC58).
  3. Surface hardening can significantly improve hardness, but the core material will remain less hard and less wear-resistant.


Quenching and Tempering Treatment

Quenching and tempering treatment provides good comprehensive mechanical properties, widely used for various structural parts, especially those under alternating loads like shafts, bolts, gears, and axles. Surface hardness is low and wear resistance is poor, but the combined treatment can improve surface hardness.

Carburizing Treatment

Used for wear-resistant, impact-resistant heavy-duty parts like gears and shafts. Surface carbon content ranges from 0.8 to 1.2%, while core content is typically 0.1 to 0.25%. The treatment increases surface hardness and wear resistance (HRC58-62).

  • Performance: Uniform high hardness after carburizing, improving wear resistance.


40Cr Steel

Medium-carbon quenched and tempered steel, often used for important quenched and tempered parts such as drive shafts and high-strength parts. It offers high mechanical properties post-treatment, with surface hardness reaching HRC45-52 after quenching.

  • Features: Post-nitriding treatment can achieve higher surface hardness compared to 45 steel, improving fatigue resistance and life span.

T10 Steel

Carbon tool steel, heat treatment range: 58-64 HRC.

  • Features: Moderate hardness, cost-effective, with heat treatment achieving hardness over 60HRC. Suitable for high wear-resistance applications.
  • Applications: Suitable for making high-hardness wear-resistant tools, punches, and molds.

stainless steel bearing component

20 Steel

High-quality carbon structural steel, heat treatment: carburizing depth 0.8-1.2mm, HRC58-64, surface oxidation treatment.

  • Features: High hardness, good cold plasticity. Suitable for parts requiring complex shapes and substantial strength.
  • Applications: Generally used for manufacturing parts that need high toughness and strength, such as gears and axles.


Q235 Steel

Difference between hot-rolled and cold-rolled steel:

  • Features: Hot-rolled steel has good formability and toughness, while cold-rolled steel offers higher strength and better surface finish.
  • Applications: Hot-rolled steel is commonly used in automobile manufacturing and bridge construction, whereas cold-rolled steel is used in appliances and precision instruments.
  • Hot Rolling: Conducted at high temperatures, providing good ductility and malleability.
  • Cold Rolling: Done at room temperature, offering higher strength and a smooth surface finish.

Dual Phase Steels

Dual-phase steels, like Q235, undergo special heat treatments to enhance mechanical properties, making them suitable for high-stress applications such as automotive parts and structural components. These descriptions cover the performance and applications of various steels used in machining, offering a detailed look at their properties and suitable uses in industry.

Commonly Used Spring Steels

1. 70 Steel

This steel has high strength but relatively low hardenability, making it suitable for manufacturing springs with a small cross-sectional area (φ ≤ 15mm). The hardened steel wire, when cold-formed, only requires low-temperature tempering to relieve stress. This steel has good machinability but significant deformation during quenching. It is mainly used for manufacturing small-sized springs, tension springs, elastic washers, and stop rings that do not require quenching.

stainless steel 303 EDM CNC grinding

2. T9A

This steel is a high-grade carbon tool steel and spring steel. After quenching and tempering, it has high hardness and elasticity, good hardenability, and plasticity. It is commonly used to manufacture springs and tools that require high hardness and are not subjected to severe vibrations and impacts.

3. 65Mn

This is a commonly used spring steel. It has high strength, good hardenability, low decarburization tendency, and low cost. It is also sensitive to overheating and prone to temper brittleness but has good comprehensive properties. It is widely used for manufacturing various flat springs, round springs, and leaf springs.

CNC bead blasting steel

4. 60Si2MnA

This is a widely used silicon-manganese spring steel. After quenching and tempering, it has high strength and excellent elastic properties (δ0.2/δb) and its fatigue performance is superior to that of other silicon-manganese steels. It has good machinability and is mainly used for making leaf springs, coil springs, and other types of springs with a cross-sectional area of 10mm to 25mm.

5. 50CrVA

This is a high-grade quality spring steel. It has high yield strength and resistance to fatigue, as well as good plasticity and toughness. It has excellent temper stability and maintains elasticity when heated to 300°C. The steel has good machinability but poor cold plasticity. Welding performance is average. It is suitable for manufacturing important springs subjected to large loads and stresses, with a maximum operating temperature of 400°C.

Stainless Steel 3D Printing Solutions


In summary, choosing the right steel is essential for optimizing CNC machining performance and achieving superior product quality. Each of the ten steel types discussed—ranging from 45 Steel to 50CrVA—offers unique properties and benefits that cater to different industrial needs. Understanding these characteristics helps engineers and procurement professionals select the most suitable material for their specific applications, ensuring durability, efficiency, and cost-effectiveness.

At Modo Rapid, we pride ourselves on 20 years of expertise in custom CNC steel part machining. Our deep knowledge of various steel properties allows us to provide the best solutions for your projects. Contact our engineering team today for a comprehensive cost calculation and feasibility analysis tailored to your needs.

We value your thoughts and experiences. Please leave a comment below to share your insights or ask any questions about steel choices for CNC machining.

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