This article references the Metal Materials Encyclopedia and the national standard GB/T 699-2015, providing a detailed analysis of the performance characteristics and processing key points of 10F rimmed steel. 10F is one of the lowest carbon grades in the high-quality carbon structural steel rimmed steel series, exhibiting excellent cold stamping formability. Rimmed steels are characterized by their low silicon content and a distinctive ingot solidification structure that yields a clean, defect-free surface, making 10F particularly suitable for applications requiring deep drawing and intricate forming. Understanding the interplay between its chemical composition and mechanical properties is essential for optimizing both forming and subsequent machining operations.
1. Basic Information of 10F
10F is a high-quality carbon structural steel conforming to the GB/T 699-2015 standard. The “10” denotes an average carbon content of approximately 0.10%, while the “F” indicates rimmed steel (Rimmed Steel). This grade features low carbon content and very low silicon content (≤0.07%), providing excellent cold stamping formability and deep drawing capability. It is widely used for manufacturing various stamping parts, shells, containers, and similar components. Because its smelting method produces rimmed steel, it offers good surface quality but exhibits significant central segregation. The low carbon level also imparts excellent weldability and ductility, though the inherent segregation can lead to local variations in mechanical properties if not carefully controlled during processing. In practice, manufacturers often specify rimmed steel grades like 10F for thin-gauge stampings where surface finish is paramount and core strength requirements are moderate.
2. Chemical Composition
| Element | Content (%) |
|---|---|
| Carbon (C) | 0.07-0.13 |
| Silicon (Si) | ≤0.07 |
| Manganese (Mn) | 0.25-0.50 |
| Phosphorus (P) | ≤0.035 |
| Sulfur (S) | ≤0.035 |
| Chromium (Cr) | ≤0.15 |
| Nickel (Ni) | ≤0.30 |
| Copper (Cu) | ≤0.25 |
The tightly controlled composition of 10F ensures consistent formability and weldability. The very low silicon content (≤0.07%) is a hallmark of rimmed steels, as it minimizes deoxidation and promotes the characteristic rimming action during solidification. This composition results in a ferrite matrix with limited pearlite, providing excellent plasticity but relatively low strength. The manganese content, balanced between 0.25-0.50%, helps to offset the sulfur embrittlement tendency and provides moderate solid-solution strengthening. The residual elements (Cr, Ni, Cu) are kept low to avoid detrimental effects on formability and to maintain a homogenous microstructure in the as-rolled condition.
3. Mechanical Properties
| Performance Index | Value | Condition |
|---|---|---|
| Tensile Strength | ≥335 MPa | Normalized |
| Yield Strength | ≥205 MPa | Normalized |
| Elongation | ≥31% | Normalized |
| Reduction of Area | ≥55% | Normalized |
| Hardness | ≤137 HB | Hot-rolled or Annealed |
The mechanical properties of 10F after normalization reflect its low-carbon ferritic nature: moderate tensile and yield strengths paired with high elongation and reduction of area. The minimum elongation of 31% underscores its suitability for severe cold forming operations, such as deep drawing of complex shapes. The hardness specification (≤137 HB) in the hot-rolled or annealed condition ensures that the material remains soft enough for subsequent cold working without excessive tool wear. It is important to note that these properties are typical for the normalized state; if the material is supplied in the as-rolled condition without normalizing, the strength may be slightly higher due to residual cold work from the rolling process.
4. Heat Treatment Characteristics
The heat treatment characteristics of 10F, as a low-carbon rimmed steel, are as follows:
- Normalizing: 910-940 °C, air cooling, refines grain size and homogenizes the structure.
- Annealing: 680-730 °C, furnace cooling or air cooling, relieves stress and restores plasticity.
- Carburizing: Surface carburizing can be performed (920-940 °C). After carburizing, quenching plus low-temperature tempering achieves high surface hardness.
- Not applicable: Quenching and tempering, because the carbon content is too low to effectively increase strength through quenching.
Normalizing at 910-940 °C is the most common heat treatment for 10F, serving to eliminate the coarse as-cast or as-rolled grain structure and to improve uniformity. Annealing at subcritical temperatures (680-730 °C) is used primarily for stress relief after heavy cold working or for softening between forming passes. Because 10F has negligible hardenability, conventional through-hardening treatments are ineffective; however, carburizing can create a hard, wear-resistant case (0.6-0.9% C) while retaining a ductile core, making the grade suitable for lightly loaded gears and shafts. The low carbon content also renders 10F immune to quench cracking, which is a distinct advantage in complex carburized parts.
5. Typical Applications
- Cold stamping parts (automotive structural brackets, reinforcement plates)
- Deep drawn parts (cylinders, shells, heads)
- Home appliance enclosures (washing machine cabinets, air conditioner housings)
- Hardware items (hinges, brackets, stamped angles)
- Container manufacturing (low-pressure vessels, storage drums)
- CNC machined parts (subsequent precision drilling, milling of stamped blanks)
The applications of 10F span automotive, appliance, and general industrial sectors where cost-effective, highly formable steel is required. In automotive construction, it is often specified for interior brackets, seat components, and oil pans that demand deep drawing and moderate strength. For home appliances, the excellent surface quality after forming and painting is a key selection criterion. In container manufacturing, 10F’s weldability allows for straightforward fabrication of low-pressure tanks and drums. The material also serves as a base for subsequent CNC machining of features that require close tolerances, such as mounting holes and contours on stamped blanks.
6. CNC Machining Performance
CNC machining characteristics of 10F:
- Cutting performance: Low-carbon steel is relatively soft and tends to adhere to the tool. Machining requires the use of tools with large rake angles to avoid built-up edge.
- Cutting speed: 160-260 m/min (coated cemented carbide tools).
- Tool selection: Ultra-fine grain cemented carbide with PVD coating (TiN/TiAlN), rake angle 12-18°.
- Cooling: Adequate use of emulsion cutting fluid, concentration 5-8%.
- Clamping: The material is relatively soft; clamping force should not be excessive to avoid surface indentation.
When machining 10F, the primary challenge is its low hardness and high ductility, which promote the formation of a built-up edge (BUE) on the cutting tool. To mitigate this, cutting tools with positive rake angles (12-18°) and sharp edges are recommended, along with high cutting speeds (160-260 m/min) that generate sufficient heat to soften the chip and reduce adhesion. Cemented carbide inserts with a PVD TiAlN coating provide a good balance of wear resistance and low friction. A generous flow of emulsion coolant (5-8% concentration) is essential for chip evacuation and temperature control. Clamping forces must be carefully regulated to avoid deforming the thin, soft workpiece; using soft jaws or vacuum fixturing is often preferable for sheet metal parts.
7. Purchasing Guide
Market price reference (2025 market conditions):
- Cold-rolled sheet (0.5-3 mm): 5-7.5 RMB/kg
- Hot-rolled plate (3-12 mm): 4-6 RMB/kg
- Cold-rolled strip: 5-8 RMB/kg
- Round bar/wire rod: 4-6 RMB/kg
The price of 10F varies depending on the product form, thickness, and surface finish. Cold-rolled sheet and strip command a premium due to the superior surface quality and dimensional accuracy needed for stamping applications. Hot-rolled plate is more economical for thicker sections where surface appearance is less critical. When sourcing 10F, it is advisable to specify the delivery condition (e.g., annealed, normalized, or as-rolled) and ensure compliance with GB/T 699-2015 lot testing requirements for chemical composition and mechanical properties. Bulk purchasing and long-term agreements can yield cost reductions of 5-10% over spot market prices.
8. Data Sources
- GB/T 699-2015 Quality Carbon Structural Steels
- Metal Materials Encyclopedia 10F Special Entry
The technical data presented here is drawn from the authoritative Chinese national standard GB/T 699-2015 and a dedicated entry in the Metal Materials Encyclopedia. Engineers and buyers are encouraged to refer to the latest edition of the standard for any updates or amendments, as well as to consult with material suppliers for mill certificates that confirm the specific heat characteristics. These references provide a reliable foundation for material selection and process planning in applications ranging from cold stamping to CNC finishing.
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