JIS SK3M Water Hardening Tool Steel Rod/Bar

JIS SK3M Water Hardening Tool Steel Rod Product Information -:- For detailed product information, please contact sales. -: JIS SK3M Water Hardening Tool Steel Rod Synonyms -:- For detailed product information, please contact sales. -:

JIS SK3M Water Hardening Tool Steel Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: JIS SK3M Free-Machining Water-Hardening Tool Steel** ## **Overview** **JIS SK3M** is a **free-machining, high-carbon, water-hardening tool steel** defined in the Japanese Industrial Standards (JIS) as the **free-cutting variant of JIS SK3**. The **"M" suffix denotes a resulfurized, free-machining grade**, engineered with intentionally added sulfur to dramatically improve machinability in the annealed state. While retaining the fundamental hardening characteristics and high-carbon base of SK3, SK3M is optimized for **high-volume production of complex tools** where reducing machining time, improving tool life, and achieving superior surface finish prior to hardening are critical manufacturing objectives. This enhancement comes at the expense of reduced mechanical properties, particularly toughness and weldability. ## **1. Chemical Composition (JIS G 4404 - Free-Cutting Tool Steels)** SK3M's chemistry modifies standard SK3 with elevated sulfur and manganese. | Element | Content (%) | Primary Function | |---------|------------|------------------| | **Carbon (C)** | **1.00 - 1.10** | Provides the matrix for high hardness upon quenching and tempering. | | **Sulfur (S)** | **0.08 - 0.15 (Min)** | **Key element.** Forms manganese sulfide (MnS) inclusions that act as internal chip breakers and lubricants, drastically improving machinability. | | **Manganese (Mn)** | **0.60 - 1.00** | **Elevated.** Increased to safely combine with the high sulfur content, forming benign globular MnS inclusions and preventing the formation of brittle iron sulfide (FeS) at grain boundaries. | | **Silicon (Si)** | ≤ 0.35 | Deoxidizer. | | **Phosphorus (P)** | ≤ 0.03 | Impurity, kept low. | | **Chromium (Cr)** | ≤ 0.30 | Residual. | | **Nickel (Ni)** | ≤ 0.25 | Residual. | | **Copper (Cu)** | ≤ 0.25 | Residual. | | **Iron (Fe)** | Balance | Base metal. | **Key Chemistry Note:** The defining feature of SK3M is its **high sulfur content (≥0.08%) combined with proportionally high manganese**. This creates a uniform dispersion of **manganese sulfide (MnS) inclusions** throughout the steel. These inclusions: * **Promote short, broken chips** instead of long, continuous ones. * **Reduce cutting forces and tool wear.** * **Improve surface finish** on machined parts. However, these same inclusions **severely degrade transverse ductility and impact toughness**, introduce **anisotropy** (direction-dependent properties), and make the steel **essentially non-weldable**. ## **2. Physical & Mechanical Properties** *Properties are similar to SK3 in the hardened state but with significant anisotropy and reduced toughness.* | Property | Typical Value / Condition | |----------|--------------------------| | **Annealed Hardness** | 183-217 HB (with **exceptional machinability**). | | **Hardened & Tempered Hardness** | **58-63 HRC** (Achievable, but with lower effective toughness than SK3). | | **Machinability (Annealed)** | **Excellent.** Rated 80-100% of 1212 free-machining steel, vastly superior to standard SK3. | | **Impact Toughness** | **Low and Anisotropic.** Significantly lower than SK3, especially in the **transverse direction** due to alignment of MnS stringers. Unsuitable for shock loads. | | **Wear Resistance** | **Good.** Comparable to SK3 when hardened to the same hardness. | | **Hardenability** | **Very Shallow.** Identical to SK3. | | **Hot Hardness** | **Very Poor.** | | **Weldability** | **Very Poor to None.** High sulfur causes severe hot cracking; welding is not recommended. | | **Grindability** | Good. | ## **3. International Standards & Cross-References** | Standard | Designation | Notes | |----------|------------|-------| | **JIS** | **SK3M** (JIS G 4404) | Free-cutting tool steel standard. | | **AISI (USA)** | No direct equivalent. Closest conceptual match is a **sulfurized AISI W1** (e.g., W1-10 with added S). AISI uses "F" to denote resulfurized free-machining grades. | | | **ISO (International)** | No direct equivalent. | | | **DIN (Germany)** | No direct equivalent. | | | **Common Name** | **Free-Machining 1.0% Carbon Tool Steel, Sulfurized SK3** | | ## **4. Product Applications** SK3M is specifically selected for **manufacturing efficiency** when producing tools with **complex geometries** that are expensive to machine from standard SK3, and where the final tool will be used in **stable, non-impact applications**. **Primary Applications:** * **Complex Cutting Tools:** **Taps, dies, reamers, form-relieved milling cutters, gear cutters** produced in large quantities. * **Intricate Forming Tools:** **Punches and dies with complex profiles** for stamping, molding, or engraving. * **Precision Gauges and Fixtures** requiring extensive milling, drilling, and threading. * **Machine Components** like lead screws or parts requiring high hardness and extensive machining. * **High-volume production of parts** where machining cost dominates total part cost. **Applications to Avoid:** * **Any tool subject to impact, bending, or shock loading** (e.g., chisels, punches for thick material). * **Tools requiring welding, repair, or modification.** * **Structural components** where directional strength is critical. * **High-temperature applications.** * **Tools used in cyclic loading or fatigue conditions.** ## **5. Heat Treatment Guidelines** Heat treatment follows the same principles as SK3 but requires extra caution due to the stress-concentrating effect of MnS inclusions. * **Annealing:** Typically supplied annealed. If necessary, anneal at 750-780°C, slow cool. * **Hardening:** 1. **Preheating is critical** to minimize thermal shock. 2. **Austenitize at 780-820°C (1435-1510°F).** 3. **Quenching is high-risk.** Quench in **agitated water or brine**. The MnS inclusions act as stress raisers, **making SK3M even more prone to quench cracking than SK3**. **Interrupted quenching (water to ~300-400°C, then oil/air) is strongly recommended** for all but the simplest shapes. * **Tempering:** * **Temper immediately.** * Use standard tempering temperatures (150-350°C) based on desired hardness. * **Double tempering is highly recommended** to relieve stresses around inclusions. ## **6. Key Advantages & Critical Trade-Offs** **Advantages:** * **Superb Machinability:** Drastically reduces production time, improves tool life, and enhances surface finish in the soft state. * **Cost-Effective for Complex Parts:** Lowers high-volume manufacturing cost for intricate tools. * **Retains High Hardness Potential** of the base SK3 grade. **Critical Trade-Offs & Limitations:** * **Severely Reduced Toughness:** Particularly in the transverse direction. **The primary drawback.** * **High Quench Cracking Sensitivity:** More prone to cracking during heat treatment than non-free-machining grades. * **Anisotropic Properties:** Mechanical properties are directionally dependent. * **Non-Weldable.** * **All inherent limitations of water-hardening steels remain** (shallow hardenability, distortion, poor hot hardness). **Modern Context & Alternatives:** SK3M addresses a specific **manufacturing challenge** but introduces significant **performance compromises**. Modern alternatives often provide better solutions: 1. **Oil-Hardening Free-Machining Steels:** Grades like **AISI O6** (graphitic) or modified **O1/O2** types offer much safer quenching and good machinability without such severe toughness loss. 2. **Machining of Pre-Hardened Steels:** Using **PM-HSS** or **hardened alloy steels** with advanced cutting tools (carbide, CBN) can sometimes bypass the need for machining in the soft state. 3. **Electrical Discharge Machining (EDM):** Allows complex shapes to be produced in fully hardened, tough tool steels (like A2, D2), eliminating machinability concerns entirely. **Conclusion:** JIS SK3M is a **specialist manufacturing material**. Its use is justified **only when** the following conditions are met: 1) Tool design is geometrically complex and costly to machine, 2) Production volume is high enough to realize significant cost savings, 3) The final tool application is purely wear-based with **absolutely no impact or shock**, and 4) Water-hardening is an acceptable process. For most tooling applications, the compromises in toughness, reliability, and heat treatment safety make **oil-hardening free-cutting grades or alternative manufacturing processes** a more robust and preferable choice. --- **Disclaimer:** **JIS SK3M is a brittle material with very low impact resistance and high quench cracking susceptibility.** It should never be used in safety-critical applications or where shock loading is possible. The improved machinability comes with major sacrifices in mechanical integrity and heat treatment safety. Always validate the tool's performance in its intended service, considering anisotropic behavior. For new designs, strongly consider oil-hardening free-machining steels or modern machining methods before specifying SK3M. -:- For detailed product information, please contact sales. -: JIS SK3M Water Hardening Tool Steel Specification Dimensions Size： Diameter 20-1000 mm Length <6789 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 SK3M Water Hardening Tool Steel Properties -:- For detailed product information, please contact sales. -:

Applications of JIS SK3M Water Hardening Tool Steel Rod -:- For detailed product information, please contact sales. -: Chemical Identifiers JIS SK3M Water Hardening Tool Steel Rod -:- For detailed product information, please contact sales. -:

Packing of JIS SK3M Water Hardening Tool Steel Rod -:- 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 Rod 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 3260 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