Understanding X40 Cobalt Alloy UNS R30031: Composition, Properties, and Uses

In the world of high-performance materials, the X40 Cobalt Alloy UNS R30031 stands out as a remarkable contender, offering a unique blend of composition, properties, and applications. What makes this alloy so special, you ask? The answer lies in its intricate chemical makeup and exceptional mechanical properties, which make it indispensable in industries ranging from aerospace to medical implants. This article will guide you through the labyrinth of its chemical composition, shedding light on the roles of cobalt, chromium, tungsten, and other elements. We will delve deep into its tensile strength, fatigue resistance, and thermal conductivity, while also comparing its performance against other high-temperature cobalt-based alloys. By the end, you’ll understand why X40 Cobalt Alloy is the material of choice for critical applications in extreme environments. Ready to uncover the secrets behind its impressive performance? Let’s dive in.

Chemical Composition of X40 Cobalt Alloy

X40 Cobalt Alloy: An Overview

X40 Cobalt Alloy, also known as Stellite 31 or Alloy X – 40, is a specialized cobalt-based superalloy engineered for high-temperature and high-stress applications. Its chemical composition is precisely formulated to offer exceptional mechanical properties, corrosion resistance, and thermal stability.

Detailed Elemental Composition

Cobalt (Co)

Cobalt serves as the primary base metal, making up approximately 54 – 56% of the alloy. It provides high-temperature strength, wear resistance, and structural stability, acting as the fundamental building block of the alloy.

Chromium (Cr)

Chromium is present in the range of 24.5 – 26.5%. It forms a protective layer that boosts oxidation and corrosion resistance. This is crucial for the alloy’s durability in high-temperature environments.

Tungsten (W)

With a content of 7.0 – 8.0%, tungsten increases the alloy’s hardness and maintains its strength at elevated temperatures. It also improves wear resistance and thermal stability.

Nickel (Ni)

Nickel, accounting for 9.5 – 11.5% of the alloy, adds toughness and corrosion resistance. It improves the alloy’s ability to withstand harsh environments and exposure to chemicals, making it ideal for use in marine and industrial applications.

Carbon (C)

Carbon, in the range of 0.45 – 0.55%, raises the hardness and strength of the alloy by forming carbides. This is critical for the alloy’s wear resistance in abrasive environments.

Iron (Fe)

Iron is a minor addition, up to 2.0%. It can influence the alloy’s strength and corrosion resistance, but its content is kept low to avoid weakening the alloy’s ductility and toughness. Excessive iron can lead to the formation of brittle intermetallic compounds, which can compromise the material’s overall performance.

Silicon (Si)

Silicon, with a maximum content of 1.0%, acts as a deoxidizer and contributes to the alloy’s oxidation resistance.

Manganese (Mn)

Manganese, also up to 1.0%, helps improve the alloy’s hot workability and contributes to its strength.

Boron (B)

Boron is added in trace amounts (0.005 – 0.015%). It improves the grain boundary strength and creep resistance of the alloy.

Aluminum (Al)

Some enhanced versions of the X40 Cobalt Alloy include aluminum, which further improves oxidation resistance and mechanical properties at high temperatures. Aluminum is typically included in the range of approximately 0.7 – 1.5%.

Mechanical and Thermal Properties

Tensile Strength

X40 Cobalt Alloy exhibits significant tensile strength, a crucial property for materials subjected to high stress and temperature environments. X40’s as-cast tensile strength is about 740 MPa. Heat treatment can further enhance this property, with treated specimens achieving tensile strengths between 800 and 1,000 MPa, and in some specific conditions, even exceeding 1,640 MPa. This high tensile strength makes X40 suitable for applications requiring robust structural integrity.

Yield Strength

Yield strength, the stress at which a material begins to deform plastically, is another vital property. X40 Cobalt Alloy demonstrates a yield strength of around 430 MPa in its as-cast state. Post heat treatment, the yield strength can range from 400 to 420 MPa, with certain treatments pushing it up to 563 MPa. This property ensures that X40 maintains its shape and functionality under substantial loads.

Elongation

Elongation measures the alloy’s ductility, indicating its ability to undergo significant deformation before fracture. For X40 Cobalt Alloy, the elongation percentage ranges from 10-12% in the as-cast condition, improving slightly to 12% after heat treatment. This balance of strength and ductility is essential for components that experience both high stress and strain.

Hardness

Hardness is a critical parameter for wear resistance and durability. X40 Cobalt Alloy’s hardness in the as-cast state ranges from 25 to 35 HRC. Heat treatment can boost the hardness to 34-40 HRC, and in some cases, up to 43 HRC. This increased hardness contributes to the alloy’s longevity in abrasive environments.

Fatigue Strength

Fatigue strength refers to the material’s ability to withstand cyclic loading, a common stress in many industrial applications. X40 Cobalt Alloy is known for its high fatigue strength, making it an ideal choice for aerospace and biomedical implants, where components are frequently subjected to repetitive stress cycles.

Thermal Conductivity

Thermal conductivity is essential for materials exposed to high temperatures, as it affects heat dissipation. X40 Cobalt Alloy has a thermal conductivity of approximately 14.8 W/mK at room temperature. This property ensures efficient heat management, preventing overheating and thermal degradation.

High-Temperature Performance

X40 Cobalt Alloy excels in high-temperature environments, maintaining its mechanical properties and structural integrity. Its melting range is between 1,320 and 1,395°C, ensuring stability under extreme heat.

The alloy retains high tensile strength and creep resistance at temperatures ranging from 927 to 982°C (1,700 to 1,800°F), making it suitable for gas turbine components and other high-temperature applications.

Oxidation Resistance

Oxidation resistance is critical for materials exposed to high temperatures and oxidative environments. X40 forms a protective chromium oxide layer at temperatures up to 1,150°C, effectively resisting scaling and corrosion. This property enhances the alloy’s durability and reliability in harsh conditions.

Thermal Shock Resistance

Thermal shock resistance is the ability of a material to withstand rapid temperature changes without cracking or deforming. X40 Cobalt Alloy exhibits exceptional thermal shock resistance, maintaining stability and performance under sudden temperature fluctuations. This makes it suitable for applications in dynamic thermal environments, such as jet engines and industrial furnaces.

Effects of Heat Treatment

Heat treatment significantly influences the mechanical properties of X40 Cobalt Alloy. Solution annealing is usually done at 1,000 – 1,100°C for 2 – 4 hours, then quenched. Aging treatment, performed at 850 to 950°C for 4 to 6 hours, precipitates carbides, further boosting hardness and strength. These treatments optimize the alloy’s performance for specific industrial applications.

Comparative Analysis

Comparison with Other High-Temperature Cobalt-Base Alloys

X40 Cobalt Alloy stands out among high-temperature cobalt-base alloys due to its unique chemical composition and resultant properties. It has an optimized chromium content that strikes a good balance between oxidation resistance and high-temperature strength. While some cobalt-base alloys may have higher chromium levels for enhanced oxidation resistance, this often compromises their high-temperature strength.

X40’s tungsten content, ranging from 7-8%, contributes significantly to its hardness and stability at high temperatures. Alloys with different tungsten percentages show variations in their mechanical properties. Lower tungsten content may result in more ductility but reduced hardness, whereas higher tungsten content can increase hardness but make the alloy brittle.

The nickel content in X40 (9.5-11.5%) improves toughness and corrosion resistance. Alloys with higher nickel content might offer better corrosion resistance in specific environments but can adversely affect their thermal expansion properties.

Performance Differences in Practical Applications

In aerospace applications, X40’s high-temperature strength and fatigue resistance make it ideal for gas turbine parts. Other cobalt-base alloys may not perform as well under the high-stress, high-temperature conditions in gas turbines. For example, an alloy with lower tensile strength may deform under the high centrifugal forces in a turbine, leading to premature failure.

In the biomedical field, X40’s corrosion resistance is crucial. Some other alloys may corrode over time in the human body, releasing harmful ions. X40 forms a stable protective layer, ensuring long-term use in medical implants without significant degradation.

In power generation, X40’s resistance to thermal fatigue and oxidation is vital. Components in power plants face extreme conditions, including repeated heating and cooling cycles, and oxidative environments. Alloys less resistant to thermal fatigue may crack under these cyclic conditions, while those with poor oxidation resistance may experience material loss over time.

Detailed Case Studies in Aerospace and Biomedical Industries

Aerospace Industry Case Study

In a large-scale aerospace project, X40 was used for manufacturing nozzle vanes in a high-performance jet engine. Compared to a similar cobalt-base alloy used in an earlier engine model, X40 showed a 20% increase in service life. The earlier alloy had a lower chromium content, leading to faster oxidation and erosion of the nozzle vanes. X40’s optimized composition allowed it to maintain structural integrity under the extreme temperatures and high-velocity gas flow in the engine.

Biomedical Industry Case Study

In a medical research project, the problem of corrosion and loosening of implants was significant. X40 was introduced to create orthopedic implants. After long-term follow-up of patients, X40 implants demonstrated a significantly lower rate of corrosion and loosening compared to implants made from another cobalt-base alloy. The other alloy had a different nickel-chromium ratio, making it more susceptible to corrosion in the body’s physiological environment. X40’s corrosion-resistant properties ensured better long-term stability and reduced the need for revision surgeries.

Applications and Uses

Aerospace Components

X40 Cobalt Alloy is extensively used in the aerospace industry due to its remarkable high – temperature strength and oxidation resistance. Key applications include:

• Gas Turbine Engine Parts: The alloy is utilized in the manufacture of turbine blades, nozzles, and other components that must endure extreme thermal and mechanical stresses. It can retain mechanical integrity at temperatures up to 800°C. This ability is crucial for the reliable operation of jet engines.
• Exhaust Systems: Components such as exhaust nozzles benefit from X40’s resistance to high – temperature oxidation and thermal fatigue, ensuring long – term performance and safety in harsh environments.

Power Generation Systems

The power generation sector leverages X40 Cobalt Alloy for its excellent thermal stability and corrosion resistance. Typical uses include:

• Turbine Blades and Pump Impellers: These components in power plants, including those in nuclear facilities, must withstand high temperatures and corrosive conditions. In nuclear facilities, the alloy’s ability to resist corrosion and maintain its mechanical properties under high – temperature and high – radiation environments is essential to prevent component failure, which could have severe safety implications. X40’s mechanical reliability and resistance to thermal fatigue make it ideal for these applications.
• Control Rod Mechanisms: In nuclear reactors, X40 is used for control rods and other critical components due to its ability to resist high temperatures and corrosive environments while maintaining structural integrity.

Medical Implants

X40’s biocompatibility, combined with its wear and corrosion resistance, makes it suitable for various biomedical applications:

• Surgical Instruments: The alloy is used in surgical tools that require repeated sterilization without degradation.
• Orthopedic Implants: X40 is employed in joint replacements and other implants where long – term durability and resistance to bodily fluids are essential. Its strength and toughness contribute to the longevity and safety of these medical devices.

Valves and Gas Turbine Parts

In both industrial and aerospace applications, X40 Cobalt Alloy is used for components that must withstand high temperatures and corrosive environments:

• Valves: X40’s wear resistance and high – temperature strength make it suitable for high – performance valves in engines and industrial machinery.
• Gas Turbine Parts: Beyond aerospace, gas turbines in power plants benefit from X40’s properties, ensuring efficient and reliable operation under extreme conditions.

High – Temperature Environments

X40 is often chosen for applications that involve severe thermal conditions due to its high melting point and excellent thermal shock resistance:

• Furnace Components: The alloy is used in parts exposed to high temperatures and rapid temperature changes, such as in industrial furnaces.
• Heat Exchangers: X40’s ability to resist thermal fatigue and corrosion makes it ideal for heat exchangers that operate in aggressive environments.

Industrial and Chemical Processing

The alloy’s resistance to wear, corrosion, and high temperatures makes it valuable in industrial and chemical processing:

• Machinery Components: X40 is used in parts that face harsh mechanical and thermal conditions, ensuring long – term performance and reduced maintenance.
• Chemical Processing Equipment: X40’s resistance to corrosive acids and high temperatures directly enhances the efficiency of chemical processes by minimizing equipment degradation and downtime, which is critical for chemical plants.

Automotive and Mining/Heavy Equipment Industries

In the automotive and mining/heavy equipment sectors, X40 Cobalt Alloy is employed in parts that undergo high stress and wear:

• Automotive Applications:
• Valve Seats and Gears: The alloy’s hardness and wear resistance extend the lifespan of these components, maintaining performance in demanding engine environments.
• Turbocharger Components: X40’s high – temperature strength ensures the durability and efficiency of turbochargers, which are subjected to extreme conditions.
• Mining and Heavy Equipment Applications:
• Drill Bits: The alloy’s hardness and wear resistance are critical for drilling tools that encounter abrasive conditions.
• Excavation Equipment: X40 ensures the longevity and reliability of machinery used in heavy – duty excavation, where materials must withstand significant mechanical stress.

Machinability and Processing

Machinability and Processing of X40 Cobalt Alloy

Understanding Machinability

Machinability refers to the ease with which a material can be cut, shaped, or finished using various machine tools. For X40 Cobalt Alloy, also known as Stellite 31, machinability is a critical consideration due to the alloy’s high hardness, toughness, and wear resistance. These properties, while beneficial for performance in demanding applications, present significant challenges during machining.

Factors Affecting Machinability

Hardness and Strength

X40 Cobalt Alloy exhibits high hardness levels, typically ranging from 34-40 HRC after heat treatment, and can reach up to 43 HRC in certain conditions. This high hardness contributes to exceptional wear resistance but makes the material difficult to machine. The tensile strength of the alloy, which can range from 800 to 1000 MPa and up to 1640 MPa in heat-treated conditions, also impacts machinability by requiring more robust tooling and higher cutting forces.

Work Hardening

X40 Cobalt Alloy tends to become harder as it is being machined, which is known as work hardening. This makes the material even more resistant to cutting, increasing tool wear and necessitating frequent tool changes or reconditioning.

Carbide Content

X40 Cobalt Alloy contains hard tungsten and carbon carbides, which enhance wear resistance but are abrasive to cutting tools. These carbides accelerate tool wear and necessitate the use of specialized tooling materials.

Thermal Conductivity

With moderate thermal conductivity (approximately 14.8 W/mK), X40 does not dissipate heat effectively during machining. This results in heat buildup at the cutting zone, which can damage the tool and affect the workpiece’s surface integrity. Effective cooling strategies are essential to manage this heat.

Recommended Machining Practices

Tool Material Selection

For machining X40 Cobalt Alloy, cutting tools made from materials that can withstand abrasive wear are essential. Recommended tool materials include:

• Polycrystalline Diamond (PCD)
• Cubic Boron Nitride (CBN)
• Coated Carbides

These materials offer superior wear resistance and can handle the high cutting forces required for machining X40.

Cutting Parameters

To minimize heat generation and tool wear, use lower cutting speeds and feeds. The specific parameters will vary based on the machining operation, but typical cutting speeds for X40 are significantly lower than those used for softer alloys.

Coolant Application

High-pressure, flood coolant application is crucial for removing heat and chips from the cutting zone. Effective cooling prevents tool damage and workpiece deformation, maintaining the integrity of the machined part.

Tool Geometry

Using tools with positive rake angles and sharp cutting edges helps reduce cutting forces and improve chip evacuation. This geometry aids in managing the high toughness of X40 and minimizes the risk of tool breakage.

Machining Methods

Due to the challenges associated with conventional machining, alternative methods such as grinding and Electrical Discharge Machining (EDM) are often preferred for finishing operations. These methods can achieve high precision and surface quality without the excessive tool wear associated with traditional cutting.

Heat Treatment and Machinability

Heat treatment plays a vital role in optimizing the machinability of X40 Cobalt Alloy. Pre-machining heat treatments like solution annealing at 1000-1100°C can soften the material, making it easier to machine. Post-machining heat treatments, such as aging at 850-950°C, can enhance the mechanical properties and reduce residual stresses, ensuring the final component meets performance requirements.

Processing Considerations

Casting and Heat Treatment

X40 Cobalt Alloy is typically supplied as a cast alloy and requires precise heat treatment to achieve desired properties. Solution annealing followed by aging precipitates carbides and intermetallic phases, enhancing hardness and strength.

Welding and Fabrication

Specialized welding procedures are necessary due to the alloy’s high melting point (1320-1390°C) and sensitivity to thermal gradients. Post-weld heat treatment is often required to restore the alloy’s properties.

Wear and Corrosion Resistance

The alloy’s resistance to oxidation, corrosion, and wear makes it ideal for applications in aerospace, biomedical, and industrial sectors. However, these properties also mean that machining generates tough chips and requires durable tooling.

Effective machining and processing of X40 Cobalt Alloy involve careful selection of tooling materials, controlled cutting parameters, efficient cooling, and appropriate heat treatments to balance machinability with the alloy’s superior performance characteristics.

Effects of Aluminum Addition

Impact on Alloy Performance

Incorporating aluminum into X40 Cobalt Alloy can greatly enhance its performance. Typically, aluminum is added in the range of 0.7 – 2%, with a more precise target range of 0.75 – 1.5%. This addition can enhance several key properties of the alloy, particularly its oxidation resistance and high – temperature strength.

Oxidation Resistance

Aluminum enhances oxidation resistance by forming a stable aluminum oxide (Al₂O₃) layer, which acts as a barrier to prevent further oxidation. This is particularly beneficial in high – temperature environments where the alloy is exposed to oxidative conditions, as it helps to maintain the integrity and longevity of the components.

High – Temperature Strength

The addition of aluminum also contributes to the alloy’s high – temperature strength. Aluminum forms intermetallic compounds like aluminides, which have high melting points and great thermal stability. These compounds help to reinforce the alloy matrix, allowing it to retain its mechanical properties even at elevated temperatures. This makes the alloy more suitable for applications that involve prolonged exposure to high thermal stresses.

Changes in Microstructure

Adding aluminum changes the microstructure of X40 Cobalt Alloy. Aluminum can promote the formation of finer and more stable carbide precipitates, which are crucial for the alloy’s hardness and wear resistance. These changes in the microstructure can enhance the alloy’s mechanical properties, including its tensile strength, toughness, and resistance to high-temperature deformation.

Carbide Formation

Aluminum can influence the type and distribution of carbides in the alloy. It can lead to the formation of aluminum – rich carbides, which are typically harder and more wear – resistant than those formed without aluminum. This can result in an increase in the alloy’s hardness and its ability to withstand abrasive wear.

Grain Refinement

Aluminum also helps refine grains, improving tensile strength and fatigue resistance. Grain refinement can also enhance the alloy’s ductility, allowing it to absorb more energy before fracturing.

Influence on Mechanical and Thermal Properties

Hardness and Strength

The addition of aluminum generally increases the hardness of X40 Cobalt Alloy. This is due to the formation of hard, stable phases that resist deformation. The increased hardness can be beneficial for applications requiring high wear resistance.

Thermal Stability

Aluminum enhances the thermal stability of the alloy by forming stable phases that do not degrade easily at high temperatures. This improvement in thermal stability ensures that the alloy maintains its mechanical properties over extended periods of high – temperature exposure, making it ideal for critical components in aerospace and power generation industries.

Influence on Long – Term Stability

Aluminum’s impact on the long – term stability of X40 Cobalt Alloy is notable. The formation of a protective oxide layer and stable intermetallic compounds helps in maintaining the alloy’s properties over prolonged use. This makes the alloy more reliable for long – term applications where consistent performance is crucial.

Corrosion Resistance

Aluminum contributes to improved corrosion resistance by forming a passive oxide layer that shields the alloy from corrosive environments. This is particularly important in applications such as medical implants, where the alloy is exposed to bodily fluids that can be corrosive.

Creep Resistance

The addition of aluminum can also enhance the creep resistance of X40 Cobalt Alloy. Creep resistance is the ability of a material to resist deformation under sustained high temperatures and stress. The stable phases formed with aluminum addition help in maintaining the alloy’s shape and structural integrity under such conditions.

These enhancements due to aluminum addition make X40 Cobalt Alloy a more versatile and high – performing material suitable for various demanding applications.

Frequently Asked Questions

Below are answers to some frequently asked questions:

What is the chemical composition of X40 Cobalt Alloy UNS R30031?

The X40 Cobalt Alloy, designated as UNS R30031, is a cobalt – based superalloy. Its chemical composition includes cobalt as the balance element (about 54 – 60%). Other elements and their typical content ranges are: chromium (24.5 – 26.5%), tungsten (7.0 – 8.0%), carbon (0.45 – 0.55%), nickel (9.5 – 11.5%), iron (up to 2.0%), silicon (up to 1.0%), and manganese (up to 1.0%). Some variants may have approximately 4 – 5% molybdenum, and improved versions sometimes add 0.7 – 2% aluminum. Each element plays a crucial role in the alloy’s performance, such as high – temperature strength, corrosion resistance, and wear resistance.

What are the mechanical and physical properties of X40 Cobalt Alloy?

X40 Cobalt Alloy, also known as UNS R30031, exhibits exceptional mechanical and physical properties, making it suitable for demanding applications. The alloy’s tensile strength ranges from 800 MPa to 1000 MPa under typical conditions and can exceed 1640 MPa after appropriate heat treatment. Its yield strength typically falls between 400 MPa and 420 MPa, reaching up to 563 MPa post-heat treatment. X40 Cobalt Alloy has a hardness of 34-40 HRC, which can increase to 43 HRC with heat treatment, contributing to its excellent wear resistance.

The alloy’s thermal conductivity is about 14.8 W/m·K at room temperature, and it maintains structural integrity and strength at elevated temperatures up to 800°C and beyond. X40 Cobalt Alloy also boasts high fatigue strength, superior creep resistance, and significant corrosion resistance, primarily due to its high chromium content, making it ideal for applications in aerospace, biomedical implants, power generation, and chemical processing industries.

What are the typical applications and uses of X40 Cobalt Alloy?

X40 Cobalt Alloy (UNS R30031) is extensively utilized in various high-performance applications due to its exceptional mechanical strength, high-temperature resistance, corrosion resistance, and wear resistance.

In the aerospace and aviation industry, it is used in turbine blades, combustors, afterburners, and exhaust nozzles, where components must withstand extreme thermal and mechanical stresses. The power generation industry employs X40 Cobalt Alloy in turbine blades, pump impellers, and control rod mechanisms within gas turbines and nuclear reactors, benefiting from its resistance to oxidation and thermal fatigue.

In biomedical applications, its biocompatibility and excellent wear resistance make it suitable for artificial hip and knee joints, as well as surgical instruments. The chemical processing industry uses it for valves and fittings due to its corrosion resistance in aggressive environments.

The automotive industry leverages the alloy’s strength and wear resistance for valve seats, gears, and turbocharger components, enhancing vehicle performance and longevity. Additionally, the industrial and mining sectors utilize X40 Cobalt Alloy in drill bits and excavation tools, where durability under abrasive conditions is crucial.

How does the addition of aluminum affect the X40 Cobalt Alloy?

The addition of aluminum to X40 Cobalt Alloy, also known as UNS R30031, can enhance several properties of the material. Primarily, aluminum contributes to improved high-temperature oxidation resistance by forming a protective oxide layer on the alloy’s surface. This characteristic is particularly beneficial in applications requiring prolonged exposure to high temperatures, such as aerospace and power generation components.

Aluminum also influences the microstructure of the alloy by promoting the formation of intermetallic phases or carbides, which can enhance mechanical properties like strength and creep resistance. These microstructural changes can lead to increased durability and stability under thermal stress. However, the specific effects of aluminum in X40 Cobalt Alloy are not extensively documented, and further research is needed to fully understand and optimize its influence.

What are the effects of heat treatment on the mechanical properties and machinability of X40 Cobalt Alloy?

Heat treatment significantly impacts the mechanical properties and machinability of X40 Cobalt Alloy (UNS R30031). Solution annealing at 1000-1100°C for 2-4 hours dissolves alloying elements like chromium and tungsten into a single-phase matrix, followed by rapid cooling to maintain a stable and uniform microstructure. This process enhances the alloy’s strength and prepares it for further treatments.

Aging (tempering) at 850-950°C for 4-6 hours precipitates carbides and intermetallic phases, increasing tensile strength, yield strength, and hardness, which in turn improves wear resistance and fatigue strength. However, this increased hardness can reduce machinability, making the material more challenging to cut and form.

Annealing at lower temperatures with slow cooling reduces internal stresses, enhancing ductility and toughness, which improves machinability by lowering hardness.

Can you provide more detailed guidelines on the machinability of X40 Cobalt Alloy and recommended tooling?

Machining X40 Cobalt Alloy (UNS R30031) presents significant challenges due to its high hardness, strength, and wear resistance. To effectively machine this superalloy, specialized strategies are necessary.

Use carbide tools with very hard substrates and thin PVD coatings like TiAlN or AlTiN. These coatings offer high-temperature resistance and reduce friction. For turning, choose carbide grades with a very hard substrate, while for milling, opt for grades with a semi-hard substrate to balance toughness and wear resistance.

Employ sharp, positive rake angles (13°–18°) and small honed edges (0.02–0.05 mm) to minimize cutting forces. Maintain a neutral land angle and a narrow land width (0.10–0.20 mm) to reduce heat generation and improve edge strength.

Cutting speeds should be kept low due to the alloy’s hardness. For turning, use speeds of 20–30 m/min, and for milling, 15–20 m/min. Ensure stable workpiece clamping and minimize tool overhang to avoid vibration. High-pressure coolant is essential to manage heat buildup and prolong tool life.

By following these guidelines, machinists can achieve acceptable tool life and surface finish despite the alloy’s poor machinability.