Gereedschapstaal: Cijfers, Eigenschappen en toepassingen

Tool steel is at the heart of modern manufacturing, where precision and durability are desired and demanded.

It is a specialized type of steel designed to withstand the rigors of manufacturing and industrial processes.

Known for its exceptional hardness, slijtvastheid, en kracht, tool steel is crucial in various industries, from automotive and aerospace to electronics and consumer goods.

This article delves into tool steel’s types, eigenschappen, en toepassingen, offering insights into its significance and the factors to consider when selecting the right grade for your needs.

1. What is Tool Steel?

Tool steel is a specialized category of carbon and alloy steels, designed specifically for the manufacture of tools. Here’s what makes it unique:

• Koolstof is the backbone of tool steel, contributing to its hardness and strength. Typisch, tool steels contain between 0.7% naar 1.5% koolstof.
• Legerende elementen like chromium, wolfraam, molybdeen, and vanadium are added to enhance specific properties:

• • Chroom boosts hardenability, slijtvastheid, en corrosiebestendigheid. Bijvoorbeeld, steels like D2 can contain up to 12% chroom.
  • Tungsten and Molybdenum enhance toughness and heat resistance, crucial for high-speed and hot work applications. M2 steel, a common high-speed steel, has around 6% wolfraam.
  • Vanadium forms hard carbides, improving wear resistance. AISI A11, Bijvoorbeeld, bevat 1.5% vanadium.

The history of tool steel traces back to the late 19th century when the need for more durable tools led to the development of high-speed steels.

Over time, the evolution of tool steel has seen the introduction of various grades, elk op maat gemaakt voor specifieke toepassingen:

• W1, W2 (Water-hardening steels): Eenvoudig, low-cost options for basic tools, often containing 0.90-1.40% koolstof.
• A2, D2, O1 (Cold work steels): Designed for applications where the tool doesn’t get hot, with A2 offering high wear resistance due to its 5% chroomgehalte.
• H13, H19 (Hot work steels): These can withstand temperatures up to 1200°F, with H13 containing 5% chroom en 1.5% molybdeen.

2. Types of Tool Steel

Tool steel is a versatile category of steel, each type crafted to meet specific industrial needs through a unique combination of alloying elements and heat treatments.

Here’s a detailed exploration of the different types:

Water-hardening Tool Steels (W-type):

• • Eigenschappen: With high carbon content (typisch 0.90-1.40%), these steels can be hardened by quenching in water, offering simplicity and cost-effectiveness.

• 

  • Veelvoorkomend gebruik: They are the go-to choice for basic tools like drills, reamers, stoten, and scrapers where high hardness is more important than toughness.
  • Voorbeelden:

• • • W1 bevat 1.00-1.10% koolstof, ideal for tools requiring a hard cutting edge like simple drills and punches.
    • W2 has a slightly higher carbon content (1.10-1.40%), providing even greater hardness but at the cost of reduced toughness.

Cold Work Tool Steels:

• • Subcategories:

• • • D-type (High Carbon High Chromium):

• • • • Kenmerken: With high chromium content (11-13%), these steels offer excellent wear resistance, crucial for applications where the tool must endure abrasive wear.
      • Toepassingen: They are extensively used in dies for blanking, vormen, and coining, as well as in shear blades and punches.
      • Notable Alloys:

• • • • • D2 bevat 12% chroom, providing a Rockwell C hardness of 57-62, making it ideal for tools requiring high wear resistance.

• • • O-type (Oil-hardening):

• • • • Kenmerken: Oil quenching minimizes distortion and cracking, offering a balance of wear resistance and toughness.
      • Toepassingen: Snijgereedschappen, stamping dies, and forming tools benefit from O-type steels’ properties.
      • Notable Alloys:

• • • • • O1 staal, met 0.90% carbon and 0.50% mangaan, achieves a hardness of 60-64 HRC after oil quenching, making it suitable for tools requiring good machinability and toughness.

• • • A-type (Air-hardening):

• • • • Kenmerken: Air-hardening provides high wear resistance with good toughness, minimizing distortion during heat treatment.
      • Toepassingen: Dies for blanking, vormen, and coining, as well as gauges, benefit from A-type steels’ properties.
      • Notable Alloys:

• • • • • A2 staal, met 5% chroom, offers excellent dimensional stability and a hardness of 55-59 HRC after proper heat treatment, making it a popular choice for precision tools.

Shock Resisting Tool Steels (S-type):

• • Beschrijving: Engineered for tools that face sudden impacts or shock loads, these steels excel in absorbing energy without fracturing.
  • Taaiheid: They boast high toughness, with S7 steel, Bijvoorbeeld, achieving a toughness of 25-30 ft-lbs, significantly higher than many other tool steels.
  • Gebruik: Chisels, stoten, rivet sets, and tools for heavy-duty cold working benefit from the impact resistance of S-type steels.
  • Voorbeelden:

• • • S7 steel is known for its exceptional toughness, making it ideal for tools that experience high-impact loads.

Hot Work Tool Steels:

• • Categories:

• • • H1-H19: Each grade has varying levels of heat resistance, tailored to different temperature ranges.

• • Eigenschappen: These steels maintain their hardness and toughness at elevated temperatures, making them perfect for high-temperature environments.
• • Toepassingen: They are used in die casting, het smeden van matrijzen, extrusie gereedschap, and plastic molds where the tool encounters temperatures up to 1200°F.
  • Notable Alloys:

• • • H13 bevat 5% chroom en 1.5% molybdeen, maintaining 90% of its hardness at 1100°F, making it a workhorse in die casting.
    • H19 provides even higher heat resistance, suitable for the most demanding hot work conditions, withstanding temperatures up to 1200°F.

High-Speed Steels (HSS):

• • Subcategories:

• • • M-type (Molybdenum High-Speed Steels):

• • • • Kenmerken: High heat resistance, allowing for cutting speeds up to 500 ft/min without significant loss of hardness.
      • Toepassingen: Cutting tools for lathes, freesmachines, and drills benefit from M-type steels’ ability to cut at high speeds.
      • Voorbeelden:

• • • • • M2 staal, met 6% tungsten and 5% molybdeen, is a versatile choice for general-purpose cutting tools, achieving a hardness of 60-65 HRC.

• • • T-type (Tungsten High-Speed Steels):

• • • • Kenmerken: Extremely hard, with excellent heat resistance, often used for heavy-duty applications.
      • Toepassingen: Tools for cutting tough materials at high speeds, like stainless steel or titanium, where extreme hardness is crucial.
      • Voorbeelden:

• • • • • T1 staal, met 18% wolfraam, can achieve a hardness of over 70 HRC, making it suitable for cutting tools in demanding conditions.

Special Purpose Tool Steels:

• • Overzicht: These steels are designed for niche applications where standard tool steels might not suffice, offering unique properties tailored to specific needs.
  • Voorbeelden:

• • • Plastic Mold Steels: Like P20, optimized for mold-making with good polishability and corrosion resistance.
      P20 contains 0.35-0.45% koolstof, 1.40-2.00% mangaan, En 0.30-0.50% chroom, making it ideal for molds where corrosion resistance is key.
    • Free-Machining Tool Steels: Designed to be easily machined, leuk vinden O6, which contains sulfur to enhance machinability, achieving a hardness of 55-62 HRC.

Vergelijkingstabel: Tool Steel Types

3. Properties of Tool Steel

Tool steel’s properties are what make it indispensable in the world of manufacturing and tool-making. Here’s an in-depth look at the key properties:

Hardheid en taaiheid:

• • Hardheid: Tool steel’s hardness is its ability to resist indentation, krabben, or deformation. This property is critical for tools that need to maintain a sharp cutting edge or resist wear. Bijvoorbeeld:

• • • D2 steel can achieve a Rockwell C hardness of 57-62, making it ideal for applications requiring high wear resistance.

• • Taaiheid: While hardness is essential, toughness ensures that the steel can absorb energy without fracturing. A balance between hardness and toughness is crucial:

• • • A2 steel offers a good balance, with a hardness of 55-59 HRC after tempering, but with higher toughness compared to D2, making it suitable for tools that experience impact loads.

Slijtvastheid:

• • This property is vital for tools that undergo abrasive wear, like cutting tools, sterft, and punches.
    The presence of hard carbides, formed by elements like chromium, vanadium, and tungsten, significantly enhances wear resistance:

• • • Hogesnelheidsstaalsoorten like M2, met 6% tungsten and 5% molybdeen, can retain their edge even after prolonged use due to the formation of hard carbides during heat treatment.

Hittebestendigheid:

• • For tools operating in high-temperature environments, heat resistance is key to prevent softening or distortion:

• • • Hot work tool steels like H13 maintain 90% of their hardness at 1100°F, making them suitable for die casting, smeden, and extrusion where the tool encounters high temperatures.

Bewerkbaarheid:

• • Some tool steels are designed to be machined with relative ease, reducing tool wear during shaping processes:

• • • O1 steel is known for its good machinability, making it easier to shape into complex forms before hardening.

Dimensionale stabiliteit:

• • Precision tools require materials that maintain their shape under stress or temperature changes:

• • • A2 steel has excellent dimensional stability, ensuring that tools like gauges and measuring instruments maintain their accuracy over time.

Additional Properties:

• Corrosiebestendigheid: Some tool steels, particularly those with higher chromium content like stainless tool steels, offer resistance to rust and corrosion,
  which is crucial for tools used in humid or corrosive environments.
• Thermische geleidbaarheid: This property affects how heat is transferred through the tool, influencing cooling rates and thermal expansion:

• • H13 steel has relatively high thermal conductivity, which helps in dissipating heat during hot work applications.

• Vermoeidheid weerstand: Tools that undergo cyclic loading benefit from steels with high fatigue resistance:

• • S7 steel excels in this regard, making it suitable for tools subjected to repeated impacts.

• Elasticiteitsmodulus: This measures the steel’s stiffness, indicating how much it will deform under load:

• • Hogesnelheidsstaalsoorten generally have a higher elastic modulus, allowing them to maintain their shape under cutting forces.

Balancing Properties:

• Afwegingen: Achieving an optimal balance between these properties is often a challenge. Bijvoorbeeld:

• • Increasing hardness usually decreases toughness, making the steel more brittle.
  • Enhancing wear resistance might compromise machinability.

• Warmtebehandeling: The properties of tool steel can be significantly altered through heat treatment:

• • Afschrikken increases hardness but can make the steel brittle if not followed by tempering.
  • Temperen reduces brittleness by allowing some of the martensite to transform into tougher microstructures but at the cost of some hardness.

• Legerende elementen: The addition of specific elements like chromium, wolfraam, molybdeen, and vanadium tailors the steel’s properties:

• • Chroom enhances hardenability, slijtvastheid, en corrosiebestendigheid.
  • Vanadium forms hard carbides, improving wear resistance.
  • Tungsten and Molybdenum increase toughness and heat resistance.

Summary Table: Key Properties of Tool Steel

4. Heat Treatment of Tool Steel

Heat treatment is a critical process in tool steel manufacturing, transforming the steel’s microstructure to develop the desired mechanical properties.

Here’s a detailed look at the heat treatment processes:

Importance of Heat Treatment:

• • Heat treatment enhances tool steel’s hardness, taaiheid, en slijtvastheid, tailoring these properties to suit specific applications.
    Bijvoorbeeld, a drill bit requires high hardness to cut effectively, while a hammer needs toughness to withstand impacts.

Basic Heat-Treating Processes:

• • Afschrikken: This involves heating the steel to a temperature above its critical transformation point, followed by rapid cooling in a quenching medium like water, olie, or air.
    The rapid cooling traps carbon in a hard, brittle martensite structure. Bijvoorbeeld, O1 steel might be quenched in oil to achieve a hardness of 60-64 HRC.
  • Temperen: Na het blussen, the steel is brittle. Tempering involves reheating the steel to a lower temperature, typically between 300°F to 600°F, to reduce brittleness while maintaining some of the hardness.
    Tempering at 400°F for A2 steel, Bijvoorbeeld, can yield a hardness of 55-59 HRC with improved toughness.
  • Case Hardening: This process adds a hard, wear-resistant outer layer while keeping the core tough.
    It’s done by carburizing, nitreren, or cyaniding, where carbon or nitrogen atoms diffuse into the surface layer. M2 steel can achieve a surface hardness of over 70 HRC through this method.
  • Cryogenic Treatment: Beyond traditional heat treatments, cryogenic treatment involves cooling the steel to very low temperatures (often below -300°F)
    to further enhance hardness and wear resistance by reducing retained austenite, a softer phase in steel.

Effects of Heat Treatment:

• • Hardheid: Heat treatment significantly increases the steel’s hardness, making it capable of maintaining a sharp edge or resisting indentation.
    Bijvoorbeeld, D2 steel can achieve a Rockwell C hardness of 57-62 after proper heat treatment.
  • Taaiheid: While hardness is increased, toughness can be compromised if not properly balanced.
    Tempering is crucial here, as it reduces brittleness by allowing some of the martensite to transform into tougher microstructures like tempered martensite.
  • Slijtvastheid: The formation of hard carbides during heat treatment, especially in high-speed steels, greatly improves wear resistance,
    allowing tools to cut or form materials for extended periods.
  • Dimensionale stabiliteit: Proper heat treatment ensures that tools maintain their shape under stress or temperature changes,
    which is vital for precision tools like gauges and measuring instruments.

Key Considerations:

• Heat Treatment Atmosphere: The atmosphere during heat treatment can affect the steel’s properties.
  Bijvoorbeeld, a nitrogen-rich atmosphere can enhance surface hardness through nitriding.
• Quenching Medium: The choice of quenching medium affects the cooling rate and, vervolgens, the final properties of the steel.
  Water provides the fastest cooling rate, but oil or air might be used for less distortion and cracking.
• Temperatuurregeling: Precise control of heating and cooling temperatures is essential to achieve the desired properties without introducing defects like cracking or warping.
• Post-Heat Treatment: Na warmtebehandeling, tools often undergo additional processes like stress relieving,
  which can reduce internal stresses, or surface treatments like coating or polishing to further enhance performance.

5. Applications of Tool Steel

Snijgereedschappen

• Drills: Used for creating holes in various materials. Snelstaal (HSS) boren, such as M2, are commonly used for drilling hard metals.
• Reamers: Used to enlarge and smooth existing holes. HSS reamers provide precise and smooth finishes.
• Saw Blades: Used for cutting wood, metaal, and other materials. Cold work tool steels like D2 are often used for saw blades due to their high wear resistance.

Dies and Punches

• Stempelen: Used to form sheet metal into specific shapes. Cold work tool steels like D2 and A2 are ideal for stamping dies due to their high hardness and wear resistance.
• Smeden: Used to shape metal by compressing it under high pressure. Hot work tool steels like H13 are suitable for forging dies due to their excellent heat resistance.
• Extrusie: Used to force metal through a die to create specific cross-sectional profiles.
  Hot work tool steels are often used for extrusion dies due to their ability to withstand high temperatures.

Mallen

• Spuitgieten: Used to produce plastic parts by injecting molten plastic into a mold.
  Special-purpose tool steels like P20 and 718 are commonly used for injection molds due to their good polishability and corrosion resistance.
• Spuitgieten: Used to produce metal parts by forcing molten metal into a mold. Hot work tool steels like H13 are ideal for die-casting molds due to their high strength and heat resistance.

Gauges and Measuring Instruments

• Calipers: Used to measure the dimensions of objects. Cold work tool steels like A2 are often used for calipers due to their dimensional stability.
• Micrometers: Used to measure precise distances. Cold work tool steels with high dimensional stability are ideal for micrometers.
• Gauges: Used to check the dimensions of parts. Cold work tool steels like D2 are commonly used for gauges due to their high wear resistance.

Mining and Oil Well Tools

• Drill Bits: Used to drill holes in rock and soil. High-speed steels like M2 are often used for drill bits due to their ability to cut at high speeds.
• Downhole Tools: Used in oil and gas extraction. Hot work tool steels like H13 are suitable for downhole tools due to their excellent heat resistance and strength.

Other Tools

• Knives: Used for cutting various materials. Cold work tool steels like D2 and A2 are often used for knives due to their high hardness and wear resistance.
• Scissors: Used for cutting paper, fabric, and other thin materials. Cold work tool steels like A2 are ideal for scissors due to their balance of hardness and toughness.
• Chisels: Used for carving and shaping wood and stone. Shock-resisting tool steels like S7 are suitable for chisels due to their high toughness and ability to withstand impact.

6. Selecting the Right Tool Steel

Factoren om te overwegen

• Type operatie: Snijden, vormen, or other specific operations.
• Operating Conditions: Temperatuur, stress, en omgevingsfactoren.
• Material Being Worked On: The properties of the material being processed.
• Cost vs. Performance Analysis: Balancing the cost of the tool steel with the performance requirements.

Guide on How to Choose Based on Specific Needs

1. Identify the Application: Determine the specific use of the tool.
2. Assess Operating Conditions: Evaluate the temperature, stress, en omgevingsfactoren.
3. Consider Material Properties: Understand the properties of the material being worked on.
4. Evaluate Cost and Performance: Compare the cost of different tool steels with their performance benefits.
5. Consult Experts: Seek advice from metallurgists or tool steel suppliers to ensure the best selection.

8. Uitdagingen en overwegingen

Kosten

• Duur materiaal: Tool steel can be costly, especially for high-performance grades.
  Echter, the initial investment often pays off in terms of longer tool life and reduced downtime.
• Economic Impact: Consider the overall cost-effectiveness of using tool steel in your application.
  Bijvoorbeeld, while D2 steel may be more expensive than W1 steel, its superior wear resistance can lead to lower maintenance costs over time.

Onderhoud

• Regular Inspection: Regularly inspect tools for signs of wear and damage to prevent unexpected failures.
• Proper Storage: Store tools in a dry, controlled environment to prevent rust and corrosion. Proper storage can extend the lifespan of your tools.
• Cleaning and Lubrication: Clean and lubricate tools to maintain their performance. Regular maintenance can significantly improve the longevity of your tools.

Milieu-impact

• Recycling: Consider recycling old tool steel to reduce waste and environmental impact. Many tool steel manufacturers offer recycling programs.
• Disposal: Follow proper disposal guidelines to minimize environmental harm. Proper disposal ensures that hazardous materials are handled safely.

9. Toekomstige trends

Advances in Tool Steel Metallurgy

• New Alloys: Development of new alloys with enhanced properties, such as improved wear resistance and heat resistance.
  Bijvoorbeeld, researchers are exploring the use of nanotechnology to create ultra-fine grain structures in tool steels.
• Microstructure Control: Advanced techniques for controlling the microstructure of tool steel to optimize performance.
  Microalloying and controlled cooling rates are being used to achieve specific microstructures.

Development of New Alloys or Treatments

• Oppervlaktebehandelingen: New surface treatments to enhance wear resistance and corrosion resistance. Plasma nitriding and diamond-like carbon (DLC) coatings are gaining popularity.
• Additieve productie: Use of 3D printing to create complex tool steel parts with precise geometries.
  Additive manufacturing allows for the creation of intricate designs that are difficult to achieve with traditional manufacturing methods.

10. Conclusie

Gereedschapsstaal is a vital material in manufacturing and industry, offering exceptional hardness, slijtvastheid, en kracht.
Understanding the different types of tool steel, hun eigenschappen, and their applications is crucial for selecting the right material for your specific needs.
By considering factors such as the type of operation, operating conditions, en materiaaleigenschappen, you can make informed decisions that ensure optimal performance and cost-effectiveness.
Terwijl de technologie zich blijft ontwikkelen, the future of tool steel looks promising, with new alloys and treatments enhancing its capabilities even further.

We hope this article has provided valuable insights into the world of tool steel and encourages you to explore its potential in your projects.
If you have any questions or need further assistance, voel je vrij om neem contact met ons op.