BS 970/1(83) 070M55 Nonresulfurized Carbon Steel Foil/Strip

BS 970/1(83) 070M55 Nonresulfurized Carbon Steel Foil Product Information -:- For detailed product information, please contact sales. -: BS 970/1(83) 070M55 Nonresulfurized Carbon Steel Foil Synonyms -:- For detailed product information, please contact sales. -:

BS 970/1(83) 070M55 Nonresulfurized Carbon Steel Product Information -:- For detailed product information, please contact sales. -: # **BS 970-1:1983 070M55 Non-Resulphurized Carbon Steel - Product Introduction** ## **1. Overview** **BS 970-1:1983 070M55** is a medium carbon, non-resulphurized manganese carbon steel specified under the British Standard system. The designation follows the historical BS 970 Part 1 (1983) classification system: - **"070"** indicates the approximate mean manganese content × 10 (0.70% Mn) - **"M"** signifies it is a manganese-based carbon steel - **"55"** represents the approximate carbon content × 100 (0.55% C) This steel grade offers a balanced combination of strength, toughness, and wear resistance, making it suitable for medium-stress engineering components. Being **non-resulphurized**, it is not optimized for free-machining applications but provides better uniformity and mechanical properties for forging and heat treatment applications. ## **2. Chemical Composition (Weight %)** The standard chemical composition as per BS 970-1:1983 is: | Element | Minimum (%) | Maximum (%) | Typical (%) | |----------------|-------------|-------------|-------------| | Carbon (C) | 0.50 | 0.60 | 0.55 | | Manganese (Mn) | 0.50 | 0.90 | 0.70 | | Silicon (Si) | 0.05 | 0.35 | 0.25 | | Phosphorus (P) | - | 0.050 | 0.035 | | Sulfur (S) | - | 0.050 | 0.030 | | Iron (Fe) | Balance | Balance | Balance | **Note:** Compared to resulphurized grades, 070M55 has lower sulfur content (<0.050%), which improves transverse mechanical properties and reduces anisotropy. This makes it particularly suitable for components requiring uniform properties in all directions. ## **3. Physical Properties** ### **Basic Physical Properties:** - **Density:** 7.85 g/cm³ (0.284 lb/in³) - **Melting Range:** 1480-1520°C (2696-2768°F) - **Modulus of Elasticity (E):** 205-210 GPa (29.7-30.5 × 10⁶ psi) - **Shear Modulus (G):** 80 GPa (11.6 × 10⁶ psi) - **Poisson's Ratio:** 0.29 - **Thermal Conductivity:** 49 W/m·K at 100°C - **Specific Heat Capacity:** 470 J/kg·K at 100°C - **Coefficient of Thermal Expansion:** 11.5 × 10⁻⁶/K (20-100°C) ### **Mechanical Properties (Typical):** #### **As-rolled/Normalized Condition:** - **Tensile Strength:** 650-800 MPa (94-116 ksi) - **Yield Strength (0.2% offset):** 360-480 MPa (52-70 ksi) - **Elongation (5.65√S₀):** 15-20% - **Reduction in Area:** 40-50% - **Hardness (Brinell):** 190-230 HB #### **Quenched & Tempered (Oil Quenched from 850°C, Tempered at 550°C):** - **Tensile Strength:** 850-1000 MPa (123-145 ksi) - **Yield Strength:** 700-850 MPa (102-123 ksi) - **Elongation:** 12-16% - **Impact Toughness (Charpy V-notch):** 30-50 J at 20°C - **Hardness:** 248-302 HB (25-32 HRC) #### **Annealed Condition (for machining):** - **Hardness:** 170-210 HB - **Machinability:** ~60% (relative to free-cutting steel 100%) ## **4. Heat Treatment Characteristics** **070M55** responds well to conventional heat treatments: ### **Annealing:** - **Full Annealing:** Heat to 830-850°C, furnace cool at 10-20°C/hour to 600°C, then air cool - **Process Annealing:** 650-700°C, air cool - **Resulting Hardness:** 170-210 HB ### **Normalizing:** - **Temperature:** 850-880°C - **Holding Time:** 1 hour/25 mm of thickness minimum - **Cooling:** Still air - **Purpose:** Grain refinement and homogenization ### **Hardening (Quenching):** - **Austenitizing Temperature:** 820-850°C - **Quenching Medium:** Oil (preferred for sections up to 50 mm) or warm water - **Critical Diameter (in oil):** Approximately 25-35 mm - **As-quenched Hardness:** 55-60 HRC ### **Tempering:** - **Temperature Range:** 200-650°C - **Typical Applications:** - 200-300°C: High hardness, some stress relief (50-55 HRC) - 350-500°C: Spring temper (40-50 HRC) - 550-650°C: Structural components requiring toughness (25-35 HRC) ## **5. Product Applications** **070M55** is widely used in general engineering applications requiring good strength and toughness: ### **Automotive & Transportation:** - **Axle shafts** and drive shafts - **Gears** and pinions (medium-duty) - **Crankshafts** for diesel engines - **Steering components** - **Suspension parts** ### **General Engineering & Machinery:** - **Bolts, studs, and high-strength fasteners** - **Hydraulic cylinders** and piston rods - **Machine tool parts** (shafts, spindles) - **Forged fittings** and flanges - **Agricultural machinery components** ### **Construction & Mining Equipment:** - **Wear plates** and liners - **Bucket teeth** and adapters - **Track links** for light-medium excavators - **Gear blanks** for heavy machinery ### **Special Applications:** - **Railway components** (couplings, yokes) - **Forged hand tools** (hammers, wrenches) - **Industrial rollers** and guides - **Pump shafts** and impellers ## **6. International Standards & Cross-References** **070M55** has several international equivalents: | Standard System | Designation | Remarks | |-----------------|-------------|---------| | **BS** | 070M55 (BS 970-1:1983) | Original specification; superseded by BS EN standards | | **BS EN** | 1.0535 (EN 10083-2) | Current European designation | | **DIN** | C55 (1.0535) | German equivalent | | **AFNOR** | 2C55 (NF A35-551) | French standard | | **UNI** | C55 (UNI 7846) | Italian equivalent | | **JIS** | S55C (JIS G4051) | Similar Japanese grade | | **ASTM/SAE** | 1055 (SAE J403) | American equivalent (slightly different composition range) | | **AISI** | 1055 | USA designation | | **UNS** | G10550 | Unified Numbering System | | **ISO** | Type 5 (ISO 683-18) | International standard equivalent | ### **Comparison with Key Equivalents:** - **EN 1.0535:** Nearly identical composition and properties - **SAE/AISI 1055:** Slightly different Mn range (0.60-0.90% vs. 0.50-0.90%), otherwise very similar - **JIS S55C:** Higher Si content (0.15-0.35% vs. 0.15-0.30%), otherwise comparable ## **7. Manufacturing & Processing Characteristics** ### **Forging:** - **Temperature Range:** 1150-850°C - **Finish Forging:** Above 850°C - **Cooling:** Slow cooling recommended to prevent cracking ### **Machinability:** - **Rating:** 60% (relative to 1212 free-machining steel) - **Best Condition:** Annealed or normalized - **Cutting Speed:** 25-30 m/min for turning operations - **Tool Materials:** HSS or carbide with appropriate geometry ### **Weldability:** - **Rating:** Fair to Good (with precautions) - **Preheat:** 150-200°C for sections >25 mm - **Post-Weld Heat Treatment:** Stress relieving at 550-600°C recommended - **Suitable Processes:** SMAW, GMAW, GTAW with low-hydrogen electrodes ### **Surface Hardening:** - Suitable for **induction hardening** and **flame hardening** - **Case Depth:** Up to 5 mm achievable - **Surface Hardness:** 55-60 HRC after hardening ## **8. Quality Standards & Specifications** - **BS 970-1:1983:** Original UK specification - **BS EN 10083-2:** Current European standard for quenched and tempered steels - **Delivery Conditions:** Typically supplied as-rolled, normalized, or annealed - **Surface Finish:** Black (hot rolled), bright (turned or ground), or peeled - **Testing:** Standard mechanical testing per BS EN ISO 6892-1 ## **9. Advantages & Limitations** ### **Advantages:** 1. **Good strength-to-weight ratio** for medium-duty applications 2. **Excellent response to heat treatment** (quenching and tempering) 3. **Good wear resistance** in hardened condition 4. **Suitable for surface hardening** processes 5. **Better transverse properties** than resulphurized grades 6. **Cost-effective** for many engineering applications 7. **Good forgeability** and weldability (with precautions) ### **Limitations:** 1. **Not a free-machining steel** - lower machinability than resulphurized grades 2. **Limited hardenability** compared to alloy steels 3. **Maximum hardness** limited to ~60 HRC 4. **Not suitable for corrosive environments** without protection 5. **Limited high-temperature strength** ## **10. Technical Notes** - **Hardenability:** As a carbon-manganese steel, 070M55 has moderate hardenability. Maximum hardness is achievable in sections up to approximately 25-30 mm when oil quenched. - **Microstructure:** Typically ferrite-pearlite in normalized condition, transforming to martensite/bainite upon quenching. - **Decarburization:** Susceptible to surface decarburization during heat treatment; allowance should be made in final dimensions. - **Grain Size:** Typically fine-grained when aluminum-killed, ensuring good toughness. ## **Conclusion** **BS 970-1:1983 070M55** is a versatile medium-carbon, non-resulphurized manganese steel that offers a practical balance of strength, toughness, and processability. Its position as the British equivalent of C55/1055 steels makes it widely recognized and accepted in international engineering specifications. While largely superseded by EN 1.0535 in modern standards, the 070M55 designation remains familiar in many industries, particularly in legacy specifications and certain manufacturing sectors. The steel's good response to heat treatment, combined with its relatively low cost, makes it a popular choice for a wide range of automotive, machinery, and general engineering components requiring reliable performance under medium stress conditions. -:- For detailed product information, please contact sales. -: BS 970/1(83) 070M55 Nonresulfurized Carbon Steel Specification Dimensions Size： Diameter 20-1000 mm Length <5054 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 970/1(83) 070M55 Nonresulfurized Carbon Steel Properties -:- For detailed product information, please contact sales. -:

Applications of BS 970/1(83) 070M55 Nonresulfurized Carbon Steel Foil -:- For detailed product information, please contact sales. -: Chemical Identifiers BS 970/1(83) 070M55 Nonresulfurized Carbon Steel Foil -:- For detailed product information, please contact sales. -:

Packing of BS 970/1(83) 070M55 Nonresulfurized Carbon Steel Foil/Strip -:- 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 Foil/Strip 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 1525 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