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 Introduction: BS 970-3:1991 070M55 Non-Resulphurized Carbon Steel, Normalized & Cold Drawn** ## **1. Overview and Specification** **BS 970-3:1991 070M55** in the **Normalized & Cold Drawn** condition represents a specific processing route for this medium-carbon manganese steel. This designation combines **thermal treatment (normalizing)** with **mechanical processing (cold drawing)** to produce steel bars with enhanced and consistent mechanical properties, improved dimensional accuracy, and superior surface finish compared to standard hot-rolled products. The **"Normalized"** condition indicates the steel has been heated to approximately 850-900°C, held for sufficient time to achieve a uniform austenitic structure, and then air-cooled. This process refines the grain structure, homogenizes the microstructure, and relieves internal stresses from prior hot working. Subsequent **Cold Drawing** further increases strength through work hardening, tightens dimensional tolerances, and improves surface quality. This combination is ideal for components requiring **ready-to-use precision, good strength, and predictable performance without further heat treatment by the end-user.** ## **2. Chemical Composition (Weight %)** The chemical composition adheres strictly to BS 970-3:1991, with potential tighter controls for normalized stock to ensure consistent response to thermal treatment. | Element | Specification Range (BS 970) | Typical Aim for Normalized Stock | |----------------|------------------------------|----------------------------------| | Carbon (C) | 0.50 - 0.60 | 0.55 | | Manganese (Mn) | 0.50 - 0.90 | 0.70 | | Silicon (Si) | 0.05 - 0.35 | 0.20 - 0.25 | | Phosphorus (P) | ≤ 0.050 | ≤ 0.035 | | Sulfur (S) | ≤ 0.050 | ≤ 0.030 | | Iron (Fe) | Balance | Balance | **Key Quality Notes for this Condition:** * **Consistency:** Composition is tightly controlled to ensure uniform hardenability and response to normalizing. * **Decarburization:** Cold drawing after normalizing typically results in minimal surface decarburization, a critical advantage for high-strength applications. ## **3. Physical and Mechanical Properties** ### **A. Typical Properties in "Normalized & Cold Drawn" Condition (As-Supplied)** *These properties are achieved directly from the mill and are ready for use in many applications.* | Property | Value (Typical, 20-40mm dia.) | Remarks | |-----------------------------------|--------------------------------|-------------------------------------------------------------------------| | **Tensile Strength (Rm)** | 700 - 850 MPa | Higher than normalized-only due to cold work hardening. | | **Yield Strength (Rp0.2)** | 500 - 650 MPa | Significant increase from cold drawing. Provides good resistance to yield. | | **Elongation at Break (A)** | 10% - 15% | Lower than hot-rolled due to work hardening but sufficient for many static/dynamic parts. | | **Reduction of Area (Z)** | 35% - 50% | | | **Hardness** | 200 - 250 HB | 85 - 100 HRB | | **Modulus of Elasticity (E)** | 210 GPa | | | **Surface Finish (Ra)** | 1.6 - 3.2 µm | Superior to hot-rolled, reduces need for finishing. | | **Dimensional Tolerance** | h9 to h11 (ISO) | Precision tolerances standard for cold drawn products. | ### **B. Microstructural Characteristics** * **Core Structure:** Fine, uniform ferrite-pearlite matrix resulting from normalizing. * **Grain Size:** ASTM 7-9 (Fine), consistent throughout the cross-section. * **Effect of Cold Work:** A slight increase in dislocation density and directional grain alignment near the surface, contributing to higher strength. * **Freedom from Banding:** Normalizing minimizes the ferrite-pearlite banding common in as-rolled conditions, leading to more isotropic properties. ## **4. Product Applications** Components made from **Normalized & Cold Drawn 070M55** benefit from its **excellent "out-of-the-box" combination of strength, precision, and stability.** It is commonly specified for: * **Precision Shafting & Axles:** For machinery, automotive auxiliaries, and conveyors where straightness and diameter accuracy are critical. * **Hydraulic & Pneumatic Components:** Piston rods, cylinder barrels (for machining), and valve spools. * **General Engineering Parts:** Pins, dowels, bushings, rollers, and guide rods requiring wear resistance and strength. * **Fastener Stock:** For high-strength bolts, studs, and precision pins (may require thread rolling or machining). * **Automotive Components:** Clutch shafts, steering column components, and selector forks. * **Textile & Packaging Machinery:** Precision guides, cams, and lever arms. **Advantages for the User:** 1. **Reduced Machining:** Excellent surface finish and tight tolerances minimize finish machining. 2. **Predictable Performance:** Uniform normalized microstructure ensures consistent machining, wear, and strength characteristics. 3. **No User Heat Treatment Required:** Supplied ready for manufacturing, saving time and cost. 4. **Good Weldability & Machinability:** In this condition, it offers a favorable balance for further fabrication. ## **5. International Standards and Cross-References** | Standard System | Equivalent Designation / Condition | Key Standard / Specification | |-----------------|-------------------------------------------------------------------|---------------------------------------------------------------| | **EN (Current)**| **1.0535 + N (+C)**
(e.g., EN 10083-2: C55, normalized, cold drawn) | EN 10083-2: Steels for quenching and tempering | | **DIN** | Cf 55 (1.0535) normalisiert und kaltgezogen | DIN EN 10083-2 | | **ASTM/SAE** | **Grade 1055**, normalized, cold drawn (Annealed & Cold Drawn condition is more common in ASTM) | ASTM A311: Stress-Relieved Carbon Steel Bars (Similar intent) | | **UNS** | G10550 | | | **JIS** | S55C, normalized | JIS G4051 | | **ISO** | Type 5 (Medium Carbon Manganese Steel) | ISO 683-18: Heat-treatable steels | **Important Note:** While the **material grade (070M55 / 1.0535 / 1055)** is directly equivalent, the specific **"Normalized & Cold Drawn" supply condition** is a key process specification. In modern procurement, this should be explicitly stated alongside the material grade (e.g., "EN 10083-2 1.0535, normalized and cold drawn to EN 10278"). ## **6. Processing Considerations** * **Machinability:** Good in this condition. A uniform hardness and microstructure provide consistent tool life. Use standard machining practices for medium-carbon steels. * **Further Heat Treatment:** Can be **re-hardened and tempered** if higher strength is required. The normalized structure provides an excellent, consistent starting point for quenching. **Stress Relieving** (at ~550-600°C) may be used after heavy machining to stabilize dimensions. * **Weldability:** Fair. Preheating (150-200°C) is recommended for thicker sections. Post-weld heat treatment (stress relieving) is often advisable due to the medium carbon content and the cold-worked condition. * **Straightening:** Cold straightening is possible but may induce local stresses. ## **7. Summary** **BS 970-3:1991 070M55 in the Normalized & Cold Drawn condition** is a premium, process-optimized form of this classic medium-carbon steel. It delivers a reliable and enhanced property set directly from the supplier, making it a cost-effective and high-quality choice for a wide range of precision mechanical components. Its key benefits are the synergy of a **refined, uniform microstructure from normalizing** with the **strength, precision, and finish of cold drawing.** For modern specifications, it is effectively replaced by **EN 10083-2 1.0535** specified with the appropriate **+N+C (Normalized and Cold Drawn)** condition code. -:- 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 <5056 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 1527 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