BS 970/3(91) 070M55 Nonresulfurized Carbon Steel,Normalized Cold Drawn

BS 970/3(91) 070M55 Nonresulfurized Carbon Steel,Normalized Cold Drawn Product Information -:- For detailed product information, please contact sales. -: BS 970/3(91) 070M55 Nonresulfurized Carbon Steel,Normalized Cold Drawn Synonyms -:- For detailed product information, please contact sales. -:

BS 970/3(91) 070M55 Nonresulfurized Carbon Steel,Normalized Cold Drawn Product Information -:- For detailed product information, please contact sales. -: ### **Product Datasheet: BS 970-3 (1991) 070M55 Non-Resulfurized Carbon Steel, Normalized & Cold Drawn** --- #### **1. Product Overview** This product is **BS 970-3 070M55 non-resulfurized carbon steel** supplied in a **cold drawn condition from normalized stock**, as specified under **British Standard 970-3:1991** for bright steel. This specification combines the benefits of two critical processes: **normalization** for microstructural refinement and stress relief, followed by **cold drawing** for dimensional precision and improved strength. The result is a **high-quality, consistent, and precise engineering steel** that offers superior machinability and stability compared to standard cold-drawn material, making it ideal for precision components that may undergo subsequent heat treatment or require excellent dimensional stability. #### **2. Material & Process Concept: Normalized then Cold Drawn** - **Base Material (070M55):** A medium-carbon (0.55% C), non-resulfurized steel chosen for its good balance of strength and toughness. The low sulfur content ensures better transverse properties and weldability. - **Two-Stage Processing:** 1. **Normalization:** The hot-rolled stock is reheated to approximately 850-880°C and air-cooled. This homogenizes and refines the grain structure, relieves internal stresses from rolling, and ensures a uniform, predictable starting condition for cold drawing. It produces a fine pearlite-ferrite microstructure. 2. **Cold Drawing:** The normalized bar is then drawn through a die at room temperature. This imparts tight dimensional tolerances, excellent surface finish, and increases strength via strain hardening, but **starting from a more uniform and stable base** than as-rolled stock. #### **3. International Standard & Cross-References** - **Primary Standard:** **BS 970-3:1991** - Wrought steels for mechanical and allied engineering purposes. Part 3: Bright steel for general engineering purposes. - **Modern Equivalent:** **EN 10277-2:2008** (Bright steel products). The closest material designation is **1.0535 (C55E / C55R)** supplied bright (cold drawn) from normalized stock. - **ISO Standard:** **ISO 683-1:2016**, Type C55E, cold worked. - **AISI/SAE Equivalent:** **1055** (Cold Drawn, typically from annealed or normalized stock). - **Condition Designation:** In some systems, this might be noted as "+N" (normalized) or "+NT" (normalized and tempered) before cold drawing. #### **4. Chemical Composition (% by Weight, per BS 970-3)** | Element | Content Range (%) | Role in this Processed Condition | | :--- | :--- | :--- | | **Carbon (C)** | **0.50 – 0.60** | Provides base strength; ensures good response to potential final heat treatment. | | **Manganese (Mn)** | **0.50 – 0.90** | Enhances strength and provides moderate hardenability. | | **Phosphorus (P)** | **≤ 0.050** | Impurity. | | **Sulfur (S)** | **≤ 0.050** | **Non-resulfurized:** Ensures good ductility and toughness, especially important after cold work. | | **Silicon (Si)** | **0.10 – 0.35** | Deoxidizer; strengthens the ferrite. | | **Iron (Fe)** | **Balance** | Base metal. | #### **5. Typical Physical & Mechanical Properties (As-Supplied)** *Properties reflect the combined effect of normalization (for uniformity) and cold drawing (for strength/finish).* **A. Physical Properties:** - **Dimensional Accuracy:** Meets bright steel tolerances (e.g., ISO h9/h11). Diameter control is excellent. - **Straightness:** Superior to hot-rolled; typical for precision cold-drawn stock. - **Surface Finish:** Bright, smooth, and descaled. Surface roughness (Ra) typically < 1.6 µm. - **Density:** 7.85 g/cm³ - **Microstructure:** Fine, uniform ferrite-pearlite from normalization, with a slight elongation of grains from cold drawing. **B. Mechanical Properties (Typical for ~20mm dia):** - **Hardness:** **187 – 229 HBW** *(More consistent and often slightly lower than cold-drawn-from-as-rolled due to the softer normalized starting point.)* - **Tensile Strength (Rm):** **600 – 750 MPa** (87 – 109 ksi) - **Yield Strength (Rp0.2):** **≥ 400 MPa** (58 ksi) *Enhanced by cold work, but not as high as from an as-rolled start.* - **Elongation (A):** **≥ 12%** *(Better than standard cold-drawn due to the normalized ductility reserve.)* - **Machinability:** **Very Good.** This is a key advantage. The normalized structure provides uniform hardness and good chip formation, while the cold-drawn finish ensures stable cutting and excellent surface finish on the machined part. #### **6. Key Characteristics & Advantages** - **Optimal Combination for Machining:** Arguably the best supplied condition for complex machining. It offers the **dimensional accuracy and finish of cold drawing** with the **uniform, predictable machinability and lower residual stress of a normalized microstructure**. - **Superior Dimensional Stability:** The normalization step prior to drawing removes most bulk stresses, resulting in a bar that is more stable during machining and less prone to distortion than cold-drawn-from-as-rolled material. - **Excellent Preparation for Further Heat Treatment:** If the component is to be quenched and tempered, the uniform normalized microstructure provides a consistent and optimal starting point, leading to more predictable results and less distortion. - **Consistent Performance:** Minimizes the risk of hard or soft spots sometimes found in as-rolled stock. #### **7. Primary Applications** This premium-grade stock is specified for high-quality, precision-engineered components: - **Precision Shafting and Pins:** Critical dowel pins, guide rods, actuator shafts, and spindles where dimensional accuracy and straightness are vital. - **Automotive and Aerospace Components:** Fuel injection parts, transmission components, and landing gear pins requiring high integrity. - **Hydraulic and Pneumatic Components:** Precision piston rods, valve spools, and pump parts. - **Tooling and Fixtures:** Jig and fixture components, ejector pins, and wear strips. - **General High-Quality Engineering Parts:** Bushings, spacers, and fasteners where superior finish and consistency are required. #### **8. Subsequent Processing** 1. **Machining:** The primary next step. Excellent for CNC machining, offering good tool life and finish. 2. **Stress Relieving:** Often unnecessary due to the prior normalization, but can be done after heavy machining for ultimate stability. 3. **Heat Treatment:** Can be directly quenched and tempered, or case hardened, as the normalized structure is ideal for austenitizing. #### **9. Ordering Information** - **Specify:** **BS 970-3:1991, 070M55, Normalized & Cold Drawn, Bright [Diameter and Tolerance].** - **Note:** It is important to specify **"Normalized"** in addition to "Cold Drawn" to ensure this processing route. - **Modern Ordering:** For new designs, specify: **EN 10277-2, 1.0535 (C55E), +N, bright (cold drawn).** --- **Disclaimer:** BS 970-3:1991 is a superseded standard. For new procurement, the equivalent EN standard should be used. The properties listed are typical and can vary with the degree of cold reduction (drawing) and final diameter. This material represents a higher-quality (and often higher-cost) option than standard cold-drawn bar, justified by improved manufacturing yields and part performance. Always confirm the exact condition and properties with the supplier's certification. -:- For detailed product information, please contact sales. -: BS 970/3(91) 070M55 Nonresulfurized Carbon Steel,Normalized Cold Drawn Specification Dimensions Size： Diameter 20-1000 mm Length <5195 mm Size:We can customized as required Standard： Per your request or drawing We can customized as required Properties（Theoretical） Chemical Composition -:- For detailed product information, please contact sales. -: BS 970/3(91) 070M55 Nonresulfurized Carbon Steel,Normalized Cold Drawn Properties -:- For detailed product information, please contact sales. -:

Applications of BS 970/3(91) 070M55 Nonresulfurized Carbon Steel,Normalized Cold Drawn -:- For detailed product information, please contact sales. -: Chemical Identifiers BS 970/3(91) 070M55 Nonresulfurized Carbon Steel,Normalized Cold Drawn -:- For detailed product information, please contact sales. -:

Packing of BS 970/3(91) 070M55 Nonresulfurized Carbon Steel,Normalized Cold Drawn -:- For detailed product information, please contact sales. -: Standard Packing: -:- For detailed product information, please contact sales. -: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 1666 gallon liquid totes Special package is available on request. E FORUs’ is carefully handled to minimize damage during storage and transportation and to preserve the quality of our products in their original condition