JIS SKS43 Water-Hardening Tool Steel Rod/Bar

JIS SKS43 Water-Hardening Tool Steel Rod Product Information -:- For detailed product information, please contact sales. -: JIS SKS43 Water-Hardening Tool Steel Rod Synonyms -:- For detailed product information, please contact sales. -:

JIS SKS43 Water-Hardening Tool Steel Product Information -:- For detailed product information, please contact sales. -: # **JIS SKS43 Water-Hardening Tool Steel** **International Standard:** JIS G4404 (Japan Industrial Standard) - Tool Steels --- ## **1. Overview** JIS SKS43 is a **high-carbon, non-alloyed water-hardening tool steel** representing a medium-carbon variant within the traditional water-hardening steel family. Characterized by its **simple composition, shallow hardenability, and low cost**, SKS43 provides a balance between hardness and slightly improved toughness compared to higher-carbon water-hardening grades. As a water-quenching steel, it requires rapid cooling to achieve maximum hardness, making it suitable for simple tools where extreme hardness at the cutting edge is needed and where the high distortion and cracking risks of water quenching can be managed through simple geometries and careful processing. --- ## **2. Chemical Composition (Typical Weight %)** | Element | Content (%) | | :------ | :---------- | | C | 0.80–0.90 | | Si | ≤ 0.35 | | Mn | 0.10–0.40 | | Cr | ≤ 0.30 | | W | — | | V | — | | P (max) | 0.030 | | S (max) | 0.030 | **Balance:** Iron (Fe). **Key Characteristics:** SKS43 is essentially a **plain carbon steel** with 0.80–0.90% carbon and minimal intentional alloying. This carbon level provides good hardenability for water quenching while offering slightly better toughness than the highest-carbon water-hardening grades like SKS4 (1.00–1.10% C). The absence of significant alloying elements keeps costs low but limits hardenability depth and necessitates rapid quenching in water or brine. --- ## **3. Physical & Mechanical Properties** ### **Physical Properties** - **Density:** ~7.84 g/cm³ - **Thermal Conductivity:** ~50 W/m·K (at 20°C) – Higher than alloyed tool steels - **Coefficient of Thermal Expansion:** ~12.1 ×10⁻⁶ /K (20–200°C) - **Specific Heat Capacity:** ~0.47 kJ/kg·K - **Electrical Resistivity:** Lower than alloyed steels - **Magnetic Properties:** Strongly ferromagnetic ### **Mechanical Properties (Heat-Treated)** - **Annealed Hardness:** 183–217 HB - **Hardened & Tempered Hardness:** **58–62 HRC** (surface, on thin sections) - Core hardness drops rapidly below surface on thicker sections - **Tensile Strength:** ~1800–2100 MPa (surface of fully hardened thin sections) - **Yield Strength:** ~1600–1900 MPa - **Elongation:** **Low** – Typically 5–8% (better than SKS4 but still brittle) - **Impact Toughness (Charpy):** **Fair** – 10–20 J (improved over higher-carbon water-hardening steels) - **Wear Resistance:** **Good (at surface)** – Due to high hardness but limited by low toughness - **Compressive Strength:** ~2300–2600 MPa (surface of fully hardened material) - **Fatigue Strength:** Fair – Better than SKS4 but still limited ### **Hardenability Characteristics:** - **Critical Diameter (Water Quench):** ~6–10 mm for 50% martensite at center - **Hardness Gradient:** Very steep – significant hardness drop within first 2–3 mm - **Full Hardness Depth:** Only achievable on sections < 5 mm --- ## **4. Heat Treatment Specifications** ### **1. Annealing** - **Temperature:** 740–760°C - **Process:** Heat uniformly, hold for 1–2 hours per inch of thickness, furnace cool slowly to 500°C, then air cool - **Resulting Hardness:** 183–217 HB - **Full Annealing:** 760–780°C followed by slow cooling to 500°C at ≤ 20°C/h ### **2. Stress Relieving** - **Temperature:** 600–650°C - **Hold Time:** 1–2 hours - **Purpose:** Reduce machining stresses before final hardening ### **3. Hardening (Quenching)** - **Preheating:** **Essential** to prevent thermal shock cracking - **First Preheat:** 400–500°C (critical for complex shapes) - **Second Preheat:** 700–750°C (recommended) - **Austenitizing Temperature:** **770–820°C** (typically 790–810°C) - Lower than higher-carbon grades to prevent excessive grain growth - **Soaking Time:** Short – 5–15 minutes per 25mm at temperature - Overheating causes rapid grain coarsening and embrittlement - **Quenching Medium:** **Water or brine** (5–10% NaCl solution at 20–40°C recommended) - Water: Most severe, highest hardness, highest cracking risk - Brine: Less severe than pure water, slightly lower hardness - Oil: Possible but results in significantly lower hardness (~52–56 HRC) - **Agitation:** Vigorous agitation essential for uniform cooling - **Quench Temperature:** Quench to below 100°C (preferably 40–60°C) - **Interrupted Quenching:** Sometimes used – quench in water to ~200°C, then transfer to oil ### **4. Tempering** - **Immediate Tempering Required:** Begin within 30 minutes after quenching - **Temperature Range:** - **Very Low (100–150°C):** For maximum hardness (61–62 HRC) – 1–2 hours - **Low (150–200°C):** For stress relief while maintaining hardness (59–61 HRC) – 1–2 hours - **Medium (200–300°C):** For improved toughness (56–59 HRC) – 1–2+ hours - **Avoid:** 250–350°C range (temper brittleness zone) - **Hold Time:** 1–2 hours minimum - **Cycles:** Single temper usually sufficient - **Cooling:** Air cool after tempering ### **5. Special Heat Treatment Techniques:** - **Selective Hardening:** Heating only the cutting edge or wear surface - **Lead or Salt Bath Heating:** For precise temperature control and reduced decarburization - **Pack Hardening:** Using charcoal or other carbonaceous materials to protect surface --- ## **5. Key Features & Advantages** 1. **Low Cost:** One of the most economical tool steels available 2. **High Surface Hardness:** Can achieve 61–62 HRC on properly hardened thin sections 3. **Better Toughness than SKS4:** Lower carbon content provides improved impact resistance 4. **Simple Composition:** Easy to produce and quality control 5. **Good Machinability:** In annealed state, comparable to medium-carbon steels 6. **Traditional Material:** Long history of use with well-understood behavior 7. **Sharp Edge Capability:** Can take and hold a very sharp edge when properly hardened **Limitations:** - **Poor Toughness:** Still brittle compared to alloyed tool steels - **Shallow Hardenability:** Hardness drops rapidly below surface - **High Distortion:** Severe warping during water quenching - **Cracking Sensitivity:** High risk of quench cracks, especially in complex shapes - **Limited Section Size:** Not suitable for thick sections (>8mm for reasonable hardness) - **Poor Dimensional Stability:** Unpredictable size changes during heat treatment - **Decarburization Sensitivity:** Loses carbon at surface during heating unless protected --- ## **6. Typical Applications** SKS43 is used for **simple cutting tools and components** where medium-high hardness and low cost are priorities, and where the limitations of water hardening can be accommodated. ### **Cutting Tools:** - **Woodworking Tools:** Chisels, plane irons, carving tools, turning tools - **Hand Tools:** Screwdrivers, punches, cold chisels (for light duty) - **Gardening Tools:** Pruning shears, hedge trimmers, lawn mower blades - **Textile Tools:** Fabric cutters, shears, scissors - **Leatherworking Tools:** Skiving knives, cutting blades ### **Blades and Edges:** - **Paper Cutters:** Guillotine blades, rotary cutters - **Food Processing Blades:** Slicing knives, butcher knives (traditional) - **Agricultural Blades:** Scythes, sickles, harvest knives - **Artisan Tools:** Engraving tools, linoleum cutters ### **Measuring and Layout Tools:** - **Squares and Rules:** Hardened edges - **Calipers:** Measuring surfaces - **Templates and Patterns:** For layout work ### **Simple Wear Parts:** - **Wear Plates:** Thin sections subject to light abrasion - **Guide Pins:** For low-stress applications - **Bushings:** For light duty, low-speed applications ### **Special Applications:** - **Surgical Instruments:** Scalpel blades, dental instruments (traditional) - **Razor Blades:** Straight razors, safety razor blades - **Springs:** Small, hardened springs - **Piano Wire:** High-carbon wire applications ### **Application Guidelines:** - **Best for:** Simple shapes with uniform cross-sections < 8mm - **Ideal for:** Tools that are regularly resharpened - **Suitable for:** Low-production, hand-made, or artisan tools - **Avoid for:** Complex shapes, thick sections, or impact applications - **Consider:** Selective hardening of cutting edges only --- ## **7. International Standard Equivalents** | Standard | Grade Designation | Notes | | :--------------- | :------------------ | :----------------------------------------- | | **JIS** | SKS43 | Original specification (JIS G4404) | | **AISI/SAE (USA)**| W1-0.85C | **Direct Equivalent** (Water-hardening 0.85% C) | | **DIN (Germany)** | 1.1625 | C85W1 | | **ISO** | TC80 | International designation | | **BS (UK)** | BW1A | British water-hardening grade | | **GB (China)** | T8A/T9A | Similar carbon range | | **UNS** | T72301 | Unified Numbering System (same series as W1) | **Note:** Water-hardening steels are designated by carbon content in many standards. SKS43 corresponds to approximately 0.85% carbon content. --- ## **8. Machining & Fabrication Guidelines** ### **Machining (In Annealed State):** - **Excellent Machinability:** Very good for a tool steel - **Tooling:** High-speed steel tools work excellently - **Cutting Speeds:** 30–45 m/min for turning with HSS - **Feeds:** Moderate feeds with good chip control - **Chip Formation:** Long, stringy chips typical – use chipbreakers - **Surface Finish:** Can achieve very good finishes - **Drilling and Tapping:** Good performance with standard tools ### **Grinding:** - **Good Grindability:** But requires careful technique - **Wheel Selection:** Aluminum oxide wheels (A46-HV or similar) - **Coolant:** Essential to prevent overheating and cracking - **Parameters:** Light infeeds (0.01–0.05 mm/pass) - **Wheel Speed:** 25–35 m/s - **Caution:** Grinding heat can cause localized tempering or cracking ### **Electrical Discharge Machining (EDM):** - **Possible but Risky:** High risk of microcracking in hardened state - **Parameters:** Use very conservative settings if attempted - **Post-EDM:** Must completely remove white layer by grinding - **Recommendation:** Avoid EDM on hardened SKS43 if possible ### **Welding:** - **Not Recommended:** Extremely high risk of cracking - **If Absolutely Necessary:** - High preheat: 400–450°C - Low-hydrogen electrodes - Immediate post-weld annealing - Complete re-hardening if possible - **Practical Approach:** Avoid welding – design as one piece or use mechanical fastening ### **Forming & Forging:** - **Good Forgeability:** Can be hot forged readily - **Forging Temperature:** 1050–850°C - **Start:** 1050°C maximum - **Finish:** 850°C minimum - **Cooling After Forging:** Very slow cooling (furnace cool or bury in insulating material) - **Annealing:** Always anneal after forging before machining ### **Cold Working:** - **Limited Cold Formability:** Possible in annealed state for simple bends - **Springback:** Significant due to high yield strength - **Intermediate Annealing:** Required for complex forming --- ## **9. Surface Treatment & Finishing** ### **1. Selective Hardening Methods:** - **Edge Hardening Only:** For tools where only cutting edge needs hardness - **Methods:** - **Torch Heating:** Traditional method for tools like chisels - **Induction Heating:** More controlled for production - **Salt Bath:** For uniform heating of complex edges - **Benefits:** Reduces overall distortion, maintains tough body ### **2. Case Hardening:** - **Not Typically Applied:** Already sufficient carbon content - **Possible for Special Cases:** To create ultra-high carbon surface - **Risk:** May cause excessive surface brittleness ### **3. Surface Protection During Heating:** - **Pack Hardening:** Using charcoal or cast iron chips to prevent decarburization - **Salt Bath:** Provides excellent surface protection - **Controlled Atmosphere:** Modern method using protective gases ### **4. Final Finishes:** - **Polishing:** Can achieve mirror finish on properly hardened surfaces - **Black Oxide:** Traditional finish for corrosion protection and appearance - **Phosphate Coating:** For improved corrosion resistance and lubricity - **Chrome Plating:** Decorative chrome for appearance (not recommended for cutting edges) ### **5. Traditional Techniques:** - **Clay Coating:** For differential hardening (as in Japanese sword making) - **Water Quenching Techniques:** Various traditional methods to control cooling rate --- ## **10. Performance Comparison** ### **Within Water-Hardening Tool Steels:** | Property | SKS43 (0.85C) | SKS4 (1.05C) | SKS44 (0.70C) | SKS45 (1.20C) | |-----------------------|---------------|---------------|---------------|---------------| | **Carbon Content** | 0.80–0.90% | 1.00–1.10% | 0.65–0.75% | 1.15–1.25% | | **Max Hardness** | 61–62 HRC | 63–64 HRC | 59–60 HRC | 64–65 HRC | | **Toughness** | Fair | Very Poor | Good | Extremely Poor | | **Wear Resistance** | Good | Very Good | Fair | Excellent | | **Hardenability Depth**| Shallow | Very Shallow | Very Shallow | Extremely Shallow | | **Distortion Risk** | High | Very High | Medium-High | Extremely High | | **Typical Use** | General cutting| Maximum wear | Better toughness| Extreme hardness | ### **Compared to Modern Tool Steels:** | Property | SKS43 (Water-H) | SKS3 (Oil-H) | A2 (Air-H) | D2 (High-Cr) | |-----------------------|-----------------|---------------|---------------|---------------| | **Material Cost** | **Lowest** | Low | Medium | High | | **Max Hardness** | 62 HRC | 61 HRC | 62 HRC | 62 HRC | | **Toughness** | Fair | Very Good | Good | Poor | | **Wear Resistance** | Good | Very Good | Excellent | **Excellent** | | **Distortion** | Very High | Low | Very Low | Very Low | | **Hardenability** | Shallow | Moderate | Deep | Deep | | **Processing Difficulty**| High | Moderate | Low | Low | | **Finished Tool Cost**| Often High | Moderate | Moderate | High | --- ## **11. Design Considerations for Water-Hardening Steels** ### **Geometry Restrictions:** - **Simple Shapes Preferred:** Uniform cross-sections, symmetrical designs - **Avoid:** Sharp corners, abrupt changes in section, thin webs adjacent to thick sections - **Required Radii:** Minimum 1.5–2.0 mm on all internal corners - **Holes and Recesses:** Should be machined before hardening if possible - **Symmetry:** Helps minimize distortion during quenching ### **Section Size Limitations:** - **Optimal Thickness:** 3–6 mm for full through-hardening - **Maximum Practical:** 8–10 mm (with significant hardness gradient) - **Large Sections:** Will have soft core regardless of quenching method - **Rule of Thumb:** Maximum effective hardened depth = 1–2 mm from surface ### **Stress Concentration Management:** - **Highly Sensitive:** To notches, scratches, and machining marks - **Surface Finish:** Critical – polished surfaces resist crack initiation better - **Stress Raisers:** All should be in compression zones, not tension zones ### **Distortion Control Strategies:** 1. **Symmetrical Design:** Minimizes uneven stresses during quenching 2. **Excess Stock:** Allow 0.3–0.5 mm per side for post-hardening grinding 3. **Stress Relieving:** Before final hardening 4. **Fixture Quenching:** Use fixtures to constrain shape during quenching 5. **Alternative Quenchants:** Sometimes use brine instead of water for less severe quench ### **Selective Hardening Designs:** - **Tool Design:** Incorporate extra material at cutting edges - **Hardening Method:** Plan for localized heating of wear surfaces only - **Differential Hardening:** Traditional method for tools like axes, knives --- ## **12. Quality Control & Inspection** ### **Hardness Testing:** - **Surface Hardness:** Rockwell C scale (multiple readings) - **Hardness Profile:** Essential – measure from surface to core - **File Testing:** Traditional quick test (file should skate on properly hardened surface) ### **Microstructure Examination:** - **Grain Size:** Critical – ASTM 7 or finer required - Coarse grain = brittle behavior - **Martensite Quality:** Should be fine, acicular martensite - **Decarburization:** Check surface layer (should be minimal with proper protection) - **Carbide Distribution:** In annealed state – should be spheroidized ### **Non-Destructive Testing:** - **Visual Inspection:** For cracks after quenching (use magnification if needed) - **Dye Penetrant:** For surface crack detection - **Magnetic Particle:** Effective on hardened steel - **Dimensional Checks:** Critical due to distortion ### **Performance Testing:** - **Bend Test:** For toughness assessment (limited value due to brittleness) - **Edge Retention Test:** For cutting tools - **Service Testing:** Actual use testing is most reliable --- ## **13. Historical Context & Modern Relevance** ### **Historical Development:** - **Origins:** One of the oldest tool steel types, dating back centuries - **Traditional Manufacturing:** Originally made by blister steel or crucible process - **Heat Treatment Evolution:** From simple fire quenching to controlled processes - **Blacksmith Heritage:** Fundamental material in traditional metalworking ### **Traditional Heat Treatment Methods:** - **Water Troughs:** Various designs for controlling agitation - **Brine Solutions:** Different concentrations for different cooling rates - **Lead and Salt Baths:** For precise temperature control - **Clay Coating:** For differential hardening patterns ### **Modern Manufacturing:** - **Melting:** Electric arc furnace with basic slag practice - **Deoxidation:** Aluminum killed for grain control - **Continuous Casting:** Modern production method - **Quality Control:** Modern metallurgical controls improve consistency ### **Current Relevance:** 1. **Cost-Driven Applications:** Where material cost is primary consideration 2. **Traditional Crafts:** Where historical methods are preserved 3. **Educational Use:** Teaching fundamental heat treatment principles 4. **Simple Tools:** For applications where modern steels are overqualified 5. **Developing Regions:** Where advanced steels are unavailable or unaffordable 6. **Specialist Applications:** Certain cutting applications where specific edge characteristics are desired ### **Economic Analysis:** While SKS43 has the **lowest material cost**, the total cost of finished tools often includes: - High scrap rates from cracking and distortion - Additional finishing operations (grinding to correct dimensions) - Shorter tool life in service - More frequent tool replacement - Potential production losses from tool failure For many applications, **oil-hardening grades like SKS3 may have lower total cost** despite higher material cost, due to: - Lower scrap rates - Less finishing required - Longer tool life - More reliable performance --- ## **14. Summary & Selection Guidelines** JIS SKS43 represents a **traditional water-hardening tool steel** with medium-high carbon content, offering a compromise between the extreme hardness of higher-carbon grades and slightly improved toughness. ### **Select SKS43 When:** 1. **Minimal material cost** is the absolute priority 2. Tools are **simple in geometry** (uniform cross-sections, no complex features) 3. **High surface hardness** (58–62 HRC) is required 4. Only **thin sections** (< 8mm) need to be hardened 5. Tools will be used for **light to medium duty applications** 6. **Regular resharpening** is part of the tool maintenance routine 7. **Traditional methods** are being used or are culturally important 8. **Educational purposes** require demonstrating basic heat treatment ### **Optimal Application Examples:** - **Woodworking hand tools** (chisels, plane irons, carving tools) - **Gardening tools** (pruners, shears, small cutting tools) - **Artisan and craft tools** (engraving tools, leatherworking tools) - **Simple cutting blades** for paper, fabric, soft materials - **Educational projects** in schools and training workshops - **Prototype tools** where geometry may change frequently ### **Avoid SKS43 When:** 1. **Tool reliability** is important 2. **Complex geometries** are involved 3. **Thick sections** (> 8mm) need to be hardened 4. **Impact or shock loading** will occur 5. **Dimensional precision** is required after heat treatment 6. **Production quantities** justify investment in better tooling 7. **Tool failure** would cause significant downtime or safety issues 8. **Modern heat treatment facilities** are not available ### **Heat Treatment Philosophy for SKS43:** 1. **Accept** that some distortion and size change will occur 2. **Plan** for final grinding after hardening 3. **Use** protective atmospheres or packing to prevent decarburization 4. **Control** heating and quenching very carefully 5. **Expect** some scrap – budget for it in cost calculations 6. **Consider** selective hardening of only the cutting edge when possible ### **Economic Reality:** The **total cost equation** for SKS43 often reveals that: - Material savings may be offset by higher processing costs - Scrap rates are typically higher than with oil-hardening steels - Tool life may be shorter, increasing replacement costs - For production tools, the **total cost of ownership** often favors oil-hardening grades ### **Modern Perspective:** For most industrial applications today, **oil-hardening grades like SKS3 have largely replaced water-hardening steels** because: 1. They offer significantly better toughness 2. They cause much less distortion during heat treatment 3. They allow more complex tool designs 4. They provide more reliable and consistent performance 5. The total cost per finished tool is often lower despite higher material cost 6. They reduce production risks and downtime ### **Niche Applications Where SKS43 Still Excels:** 1. **Traditional blade making** where specific heat treatment patterns are desired 2. **Hand-made artisan tools** where the craft tradition values the material 3. **Educational contexts** where the dramatic effects of heat treatment teach important principles 4. **Very specific cutting applications** where the edge characteristics of water-hardened steel are preferred 5. **Situations** where only basic heat treatment facilities are available ### **Final Recommendation:** JIS SKS43 should be considered a **specialist material for specific traditional applications** rather than a general-purpose tool steel. Its use is justified primarily in contexts where: - **Historical authenticity** is important - **Material cost** absolutely must be minimized - **Simple geometries** allow successful water quenching - **The toolmaking craft** itself is part of the product value - **Educational objectives** override pure economic considerations For modern production tooling, **oil-hardening grades (SKS2, SKS3) almost always offer better value** through improved reliability, longer tool life, and lower total cost despite higher initial material cost. However, for the specific niches where SKS43's characteristics align perfectly with requirements – particularly in traditional crafts and cost-sensitive simple tools – it remains a valid choice with centuries of historical precedent. When selecting SKS43, approach it with **respect for its limitations** and with **realistic expectations** about the challenges of water quenching. In the right hands and for the right applications, it can produce excellent results; in the wrong applications, it can lead to frustration and failure. -:- For detailed product information, please contact sales. -: JIS SKS43 Water-Hardening Tool Steel Specification Dimensions Size： Diameter 20-1000 mm Length <6826 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 SKS43 Water-Hardening Tool Steel Properties -:- For detailed product information, please contact sales. -:

Applications of JIS SKS43 Water-Hardening Tool Steel Rod -:- For detailed product information, please contact sales. -: Chemical Identifiers JIS SKS43 Water-Hardening Tool Steel Rod -:- For detailed product information, please contact sales. -:

Packing of JIS SKS43 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 3297 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