JIS SK1 Water Hardening Tool Steel

JIS SK1 Water Hardening Tool Steel Product Information -:- For detailed product information, please contact sales. -: JIS SK1 Water Hardening Tool Steel Synonyms -:- For detailed product information, please contact sales. -:

JIS SK1 Water Hardening Tool Steel Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: JIS SK1 Water Hardening Tool Steel** ## **Overview** **JIS SK1** is a **high-carbon, non-alloyed water-hardening tool steel** defined by the Japanese Industrial Standards (JIS). It is the **highest carbon grade within the JIS SK series (carbon tool steels)**, designed to achieve **maximum hardness** for applications requiring an extremely sharp, wear-resistant edge. As a plain carbon steel with minimal alloying, SK1 is characterized by **very shallow hardenability, low toughness, and the necessity for a severe water or brine quench**. It is the Japanese equivalent to steels like **AISI W1-1.4C** and is traditionally used for files, cutting tools, and other implements where supreme hardness is prioritized over impact resistance. ## **1. Chemical Composition (JIS G 4401 Standard)** SK1's composition is simple, with carbon as the dominant element. | Element | Content (%) | Primary Function | |---------|------------|------------------| | **Carbon (C)** | **1.30 - 1.50** | **The defining element.** Very high carbon content ensures maximum achievable hardness (up to ~67 HRC) and forms a high volume of hard cementite for abrasion resistance. | | **Silicon (Si)** | ≤ 0.35 | Deoxidizer. | | **Manganese (Mn)** | ≤ 0.50 | Slightly increases hardenability but kept low. | | **Phosphorus (P)** | ≤ 0.03 | Impurity, kept low. | | **Sulfur (S)** | ≤ 0.03 | Impurity, kept low. | | **Chromium (Cr)** | ≤ 0.30 | May be present residually; not an intentional alloying element. | | **Nickel (Ni)** | ≤ 0.25 | May be present residually. | | **Copper (Cu)** | ≤ 0.25 | May be present residually. | | **Iron (Fe)** | Balance | Base metal. | **Key Chemistry Note:** SK1 is essentially a **very high-carbon steel** (hypereutectoid). Its **carbon content (1.3-1.5%)** is its most critical feature, placing it at the upper practical limit for carbon tool steels. This results in a microstructure containing a **large network of primary cementite** alongside pearlite/martensite, contributing to extreme wear resistance but also significant brittleness. The **near absence of grain-refining elements (like V)** means careful heat treatment control is required to prevent coarse grain growth. ## **2. Physical & Mechanical Properties** *Typical properties in the hardened and tempered condition.* | Property | Typical Value / Condition | |----------|--------------------------| | **Density** | ~7.85 g/cm³ | | **Melting Point** | ~1470°C (2680°F) | | **Thermal Conductivity** | ~48 W/m·K | | **Coefficient of Thermal Expansion** | ~12.3 × 10⁻⁶/K (20-100°C) | | **Modulus of Elasticity** | 205-210 GPa | | **Annealed Hardness** | 201-229 HB | | **As-Quenched Hardness (Water)** | **Up to 66-68 HRC** (Theoretical maximum for steel). | | **Hardened & Tempered Hardness** | **62-66 HRC** (Common working range for files/cutting edges). Tempering is often done at low temperatures (150-200°C) to retain hardness. | | **Tensile Strength** | Very high (>2000 MPa) but with negligible ductility. | | **Impact Toughness** | **Very Low.** Extremely brittle; tools are prone to chipping or fracture under shock load. | | **Wear Resistance (Abrasion)** | **Excellent** due to high hardness and cementite volume. | | **Hardenability** | **Extremely Shallow.** Effective hardening depth is only **1-3 mm**. Thicker sections will have a hard case over a soft core. | | **Hot Hardness** | **Very Poor.** Rapid softening above **~200°C (390°F)**. | | **Machinability (Annealed)** | Fair to Poor. High carbon content makes it abrasive and can be gummy. | | **Grindability** | Fair. | ## **3. International Standards & Cross-References** | Standard | Designation | Notes | |----------|------------|-------| | **JIS** | **SK1** (JIS G 4401) | | | **AISI (USA)** | **~W1-13, W1-14** (AISI W1 with 1.3-1.4% C) | The closest direct equivalent. | | **ISO (International)** | **~C140U** (ISO 4957) | | | **DIN (Germany)** | **~C140W2** (1.1840) | High-carbon water-hardening steel. | | **BS (UK)** | **~BW1B** (High-carbon variant) | | | **GB (China)** | **T12, T13** (Carbon tool steel, though carbon ranges differ slightly) | | | **Common Name** | **1.4% Carbon Tool Steel, File Steel** | | ## **4. Product Applications** SK1 is used almost exclusively for applications where **extreme hardness and abrasion resistance are paramount**, and the tool is used in a stable, non-impact manner. **Primary Applications:** * **Files and Rasps:** The **classic application**. For machining and finishing hard metals. * **Cutting Blades and Knives:** For cutting soft metals, wood, paper, and plastics where a very sharp, hard edge is needed but shock loading is minimal (e.g., hand plane blades, some knives). * **Lathe Tools:** For precision finishing cuts on soft materials. * **Scrapers and Burnishing Tools.** * **Measuring Tools:** Surface plates, straight edges where dimensional stability and wear resistance are key. * **Metal Stamping Punches** for thin, soft materials (low volume). **Applications to Avoid:** * Any tool subject to impact or bending (cold chisels, punches for thick material). * Tools with complex shapes or sharp corners (high quench cracking risk). * High-temperature applications. * Tools requiring deep, uniform hardness. ## **5. Heat Treatment Guidelines** Heat treating SK1 is a high-skill operation due to its high carbon content and water-quenching requirement. * **Annealing:** Heat to **740-760°C (1365-1400°F)**, hold, then furnace cool very slowly to produce a spheroidized structure for machinability. * **Hardening:** 1. **Preheating:** **Essential.** Preheat slowly to **700-750°C (1290-1380°F)** to minimize thermal shock. 2. **Austenitizing:** Heat to **760-800°C (1400-1470°F).** Use the **lower end of this range** (760-780°C) to minimize grain growth and distortion. Soak for 10-20 minutes per inch. 3. **Quenching:** Quench **immediately in agitated water or brine (5-10% NaCl).** For anything other than simple shapes, an **interrupted quench** is mandatory: quench in brine until the part cools to **~300-400°C (570-750°F)** (sizzling stops, color black), then transfer immediately to oil or air. * **Tempering:** * **Temper immediately** (within 30 minutes). * To retain high hardness (64-66 HRC), temper at a **low temperature: 150-180°C (300-355°F)** for 1-2 hours. * For slightly better toughness at the expense of hardness, temper at **200-250°C (390-480°F)**. * **Avoid tempering between ~250-350°C (480-660°F)** where tempered martensite embrittlement is severe in high-carbon steels. * **Double tempering** is recommended. ## **6. Key Advantages & Severe Limitations** **Advantages:** * **Can achieve the highest possible hardness** of any standard tool steel. * **Low material cost.** * **Excellent abrasion resistance** for its cost. * **Simple metallurgy.** **Severe Limitations:** * **Extremely Brittle:** Very low impact toughness. * **Very Shallow Hardenability:** Useless for thick sections. * **Extreme Quenching Risk:** Very high susceptibility to cracking and distortion during water quenching. * **Poor Machinability** in annealed state compared to lower-carbon steels. * **No Thermal Resistance:** Loses hardness at low temperatures. * **Obsolete for Most Industrial Applications:** The risks and limitations far outweigh the advantages for all but a few niche, traditional uses. **Modern Context:** For most applications where SK1 was historically used, **alloy tool steels offer far superior solutions.** * For files and abrasive wear: **AISI D2 (12% Cr)** or specialty **powder metallurgy steels** offer better wear life and toughness. * For cutting edges: **AISI O1 or A2** provide better toughness, deeper hardening, and safer heat treatment. * SK1 remains in use primarily for **traditional file manufacturing** and specific hand tools where its performance is deeply entrenched in practice. --- **Disclaimer:** Heat treating JIS SK1 is a **high-risk process** suitable only for experienced practitioners. The combination of very high carbon and water quenching makes it one of the most crack-prone tool steels. **It is not recommended for any new, critical, or complex tool designs.** For general toolmaking, always prefer oil-hardening (O1) or air-hardening (A2, D2) steels. This profile describes the material's traditional characteristics; successful application requires accepting its inherent brittleness and manufacturing difficulties. -:- For detailed product information, please contact sales. -: JIS SK1 Water Hardening Tool Steel Specification Dimensions Size： Diameter 20-1000 mm Length <6785 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. -: JIS SK1 Water Hardening Tool Steel Properties -:- For detailed product information, please contact sales. -:

Applications of JIS SK1 Water Hardening Tool Steel -:- For detailed product information, please contact sales. -: Chemical Identifiers JIS SK1 Water Hardening Tool Steel -:- For detailed product information, please contact sales. -:

Packing of JIS SK1 Water Hardening Tool Steel -:- 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 3256 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