Material Intelligence

Material Intelligence Library

A practical reference for understanding how common engineering materials influence machining behavior, tolerance risk, cost, inspection, and part performance.

Use this library as a material-level manufacturing reference. Each material profile combines a visual intelligence card with practical interpretation of composition, strength, microstructure, machinability, manufacturing risk, and application fit.
10 material profiles

Aluminum 6061

Al-Mg-Si Alloy

Short thesis

Aluminum 6061 is one of the most practical aluminum alloys for precision-machined components when the design requires good machinability, moderate strength, corrosion resistance, weldability, and broad material availability.

Material identity

Aluminum 6061 is an aluminum-magnesium-silicon alloy commonly used in structural, fixture, prototype, housing, bracket, and general-purpose machined components.

Why engineers use it

  • Good strength-to-weight ratio
  • Excellent machinability
  • Corrosion resistance
  • Good weldability
  • Versatile extrudability
  • Broad availability in billet, bar, plate, and extruded products

Composition notes

Aluminum is the balance element, with magnesium and silicon as the primary alloying elements. Magnesium is typically around 0.80–1.20 wt%, and silicon is typically around 0.40–0.80 wt%. Copper, chromium, zinc, titanium, iron, and other elements are present in smaller controlled amounts. This chemistry helps explain why 6061 is so widely used: it offers useful strength through heat treatment while remaining much easier to machine and source than many higher-performance alloys.

Mechanical behavior

  • Tensile strength: approximately 310 MPa
  • Yield strength: approximately 276 MPa
  • Elongation: approximately 12%
  • Hardness: approximately 95 HB
  • Density: approximately 2.70 g/cm³
  • Melting range: approximately 582–652°C

Machining behavior

6061 is generally one of the more machinable aluminum alloys. It cuts cleanly with sharp tools, appropriate chip evacuation, and correct feeds and speeds. It is usually suitable for high-speed machining, tight features, prototypes, fixture components, and lower-risk precision parts. The primary machining concerns are usually related to geometry, wall thickness, burr control, chip evacuation, surface finish requirements, and whether the part is thin enough to move after material removal.

Microstructure and phase relevance

6061 is primarily an alpha aluminum FCC structure with smaller secondary phases. For practical manufacturing purposes, the important point is that 6061 behaves like a stable, machinable aluminum alloy with good process predictability compared with harder steels, titanium, and nickel alloys. Microstructure becomes more important when the part is heat treated, welded, anodized, or pushed into tighter dimensional requirements where stress, distortion, or surface response become more relevant.

Manufacturing implications

6061 is usually a strong fit when the project needs a balance of cost, machinability, corrosion resistance, and speed. From a cost perspective, it is often attractive because the material is widely available, machining behavior is predictable, and tooling risk is relatively low.

When this material is a strong fit

6061 is a strong fit when the part needs good machinability, moderate strength, low weight, corrosion resistance, and clean finishing options. It is especially practical for prototypes and production parts where cost and speed matter.

When to be careful

Be careful when the design requires very high strength, high fatigue performance, severe wear resistance, or thin geometry with tight flatness or profile requirements. In those cases, the limiting factor may not be the alloy itself, but the combination of geometry, stress relief, and tolerance expectations.

Aluminum 7075-T6

Al-Zn-Mg-Cu Alloy

Short thesis

Aluminum 7075-T6 is a high-strength aluminum alloy used when weight matters but 6061 does not provide enough strength, stiffness, or fatigue performance. It is more performance-driven, but it also requires more care around corrosion, stress, and design intent.

Material identity

Aluminum 7075-T6 is an aluminum-zinc-magnesium-copper alloy. It is a high-performance aluminum option for strength-critical applications.

Why engineers use it

  • Very high strength-to-weight ratio
  • Excellent fatigue resistance
  • Good machinability in T6 condition
  • Aerospace and defense suitability
  • Higher strength than 6061
  • Useful stiffness and structural performance for lightweight parts

Composition notes

Aluminum is the balance element, with zinc typically around 5.1–6.1 wt%, magnesium around 2.1–2.9 wt%, and copper around 1.2–2.0 wt%. Chromium is also present in a controlled range. The zinc-magnesium-copper system is what gives 7075-T6 its high strength. This same performance-oriented chemistry also makes it less forgiving than 6061 in certain corrosion and stress-related environments.

Mechanical behavior

  • Tensile strength: approximately 572 MPa
  • Yield strength: approximately 503 MPa
  • Elongation: approximately 11%
  • Hardness: approximately 150 HB
  • Density: approximately 2.81 g/cm³
  • Melting range: approximately 477–635°C

Machining behavior

7075-T6 generally machines well, especially compared with titanium, nickel alloys, and stainless steels. It can hold sharp features and good finishes when the process is stable. However, because it is stronger and harder than 6061, it may demand more attention to tool condition, fixturing, stress, and finishing strategy. For precision machining, the main concern is often not basic cutability. It is whether the part geometry, tolerance stack, and material condition support the required final shape after machining.

Microstructure and phase relevance

7075-T6 is primarily an alpha aluminum FCC structure with strengthening phases such as eta / MgZn₂ and S / Al₂CuMg. Practically, this explains the material’s high-strength behavior and why temper condition matters. The useful takeaway is that 7075-T6 is a heat-treated structural alloy. Its condition is part of the design, not an incidental material note.

Manufacturing implications

7075-T6 is a strong choice for performance parts but can add cost and scrutiny compared with 6061. Material cost is higher, and the design should be clearer about why the added strength is necessary. Manufacturing implications include higher material cost, more attention to corrosion protection, greater sensitivity to stress and heat treatment condition, and strong fit for lightweight structural applications.

When this material is a strong fit

7075-T6 is a strong fit when the part needs high strength, low weight, good fatigue behavior, and precision-machined structural performance.

When to be careful

Be careful when corrosion exposure is significant, when welding is expected, or when the part has thin, highly stressed, or distortion-sensitive geometry. Corrosion protection such as cladding or anodizing should be considered where appropriate.

17-4 PH Stainless Steel

Precipitation-Hardening Stainless Steel

Short thesis

17-4 PH stainless steel is a high-strength precipitation-hardening stainless alloy used when a part needs strength, toughness, corrosion resistance, and fatigue performance in one material system.

Material identity

17-4 PH is a precipitation-hardening stainless steel commonly used in aerospace, defense, oil and gas, chemical industry components, shafts, structural fittings, and high-load precision parts.

Why engineers use it

  • High strength and toughness
  • Corrosion resistance
  • Precipitation hardenability
  • Excellent fatigue resistance
  • Aerospace and defense suitability
  • Oil, gas, and chemical industry relevance

Composition notes

Chromium is typically around 15.00–17.50 wt%, nickel around 3.00–5.00 wt%, copper around 3.00–5.00 wt%, and niobium plus tantalum around 0.15–0.45 wt%, with iron as the balance element. Chromium supports stainless behavior, while copper and precipitation-hardening chemistry help create the strength response associated with hardened 17-4 conditions.

Mechanical behavior

  • Tensile strength in H900 condition: approximately 1150 MPa
  • Yield strength in H900 condition: approximately 1030 MPa
  • Elongation in H900 condition: approximately 12%
  • Hardness in H900 condition: approximately Rc 36–40
  • Density: approximately 7.80 g/cm³
  • Melting range: approximately 1370–1450°C

Machining behavior

17-4 PH is machinable, but the condition matters. It is generally more demanding than aluminum and many low-alloy steels, especially in hardened conditions. Tooling, heat, workholding, and finishing strategy become more important as hardness increases. For precision parts, 17-4 PH often rewards a disciplined process because it can hold meaningful performance, but it can also punish poor setup strategy, tool wear, and thermal inconsistency.

Microstructure and phase relevance

17-4 PH is primarily a martensitic BCC structure with some retained austenite and copper-rich precipitates. Practically, this explains the material’s high-strength precipitation-hardened behavior. The manufacturing significance is that 17-4 PH is not just “stainless steel.” It is a strength-tunable stainless system where condition, hardness, and heat treatment can materially affect machining and performance.

Manufacturing implications

17-4 PH can add cost through material price, harder cutting behavior, heat treatment requirements, inspection expectations, and tool wear. It is often justified when the part needs strength and corrosion resistance simultaneously.

When this material is a strong fit

17-4 PH is a strong fit when the part needs high strength, corrosion resistance, toughness, and fatigue performance without moving into nickel superalloys.

When to be careful

Be careful when the drawing does not clearly specify condition, heat treatment, hardness, or final property requirements. For 17-4 PH, the material condition is not a minor detail; it directly affects both machining and part performance.

316L Stainless Steel

Austenitic Stainless Steel

Short thesis

316L stainless steel is a low-carbon austenitic stainless alloy used when corrosion resistance, chemical compatibility, weldability, and clean service behavior matter more than maximum strength.

Material identity

316L is an austenitic stainless steel with low carbon content. It is used in marine, chemical, food, medical, and pharmaceutical environments where corrosion resistance and service compatibility are central.

Why engineers use it

  • Excellent corrosion resistance
  • Pitting and crevice corrosion resistance
  • Good weldability
  • Cryogenic to high-temperature service potential
  • Food, medical, and pharmaceutical suitability
  • Marine and chemical industry relevance

Composition notes

Iron is the balance element, with chromium typically around 16.0–18.0 wt%, nickel around 10.0–14.0 wt%, and molybdenum around 2.0–3.0 wt%. Molybdenum is one of the important differentiators from more general stainless grades because it improves resistance in aggressive corrosion environments, especially where pitting and crevice corrosion are concerns.

Mechanical behavior

  • Tensile strength: approximately 485 MPa
  • Yield strength: approximately 170 MPa
  • Elongation: approximately 40%
  • Hardness: HRE 90 max
  • Density: approximately 8.00 g/cm³
  • Melting range: approximately 1375–1400°C

Machining behavior

316L can be more difficult to machine than its strength might suggest. Austenitic stainless steels can be gummy, ductile, and prone to work hardening. Sharp tooling, controlled feeds, stable engagement, and good chip control are important. The main machining risks are built-up edge, work hardening, stringy chips, burr formation, surface finish challenges, and heat generation.

Microstructure and phase relevance

316L is primarily a gamma austenite FCC structure, with small amounts of ferrite, carbides, and other constituents. Practically, this is why 316L is ductile, corrosion resistant, and less responsive to hardening than precipitation-hardening stainless steels. The low-carbon composition helps reduce carbide precipitation concerns and supports corrosion performance in welded or corrosive service conditions.

Manufacturing implications

316L is often worth the added machining difficulty when the service environment demands it. Cost and lead time may increase compared with aluminum or easier steels, not because 316L is exotic, but because the material behavior requires controlled machining and finishing.

When this material is a strong fit

316L is a strong fit when corrosion resistance, weldability, cleanliness, biocompatibility, or chemical compatibility is more important than maximum strength.

When to be careful

Be careful when a design treats 316L like an easy general-purpose metal. It may look familiar on paper, but its machining behavior can be significantly less forgiving than aluminum, alloy steel, or some precipitation-hardening stainless conditions.

4140 Pre-Hard Steel

Chromoly Alloy Steel

Short thesis

4140 pre-hard steel is a versatile chromoly alloy steel used when a part needs strength, toughness, wear resistance, and more predictable machining than fully hardened tool steels or high-temperature alloys.

Material identity

4140 is a chromium-molybdenum alloy steel often supplied in a pre-hardened condition around 28–32 HRC. It is used for shafts, structural machine components, tooling components, wear components, high-load brackets, and industrial hardware.

Why engineers use it

  • High strength and toughness
  • Excellent wear resistance
  • Good core strength
  • Useful machinability in the pre-hard condition
  • Heat treatability for higher strength
  • Aerospace, defense, and industrial suitability

Composition notes

Carbon is typically around 0.38–0.43 wt%, chromium around 0.80–1.10 wt%, molybdenum around 0.15–0.25 wt%, and manganese around 0.75–1.00 wt%, with iron as the balance element. Chromium and molybdenum support hardenability, toughness, and strength, while the carbon level allows the material to develop useful hardness and wear resistance.

Mechanical behavior

  • Tensile strength: approximately 1150–1400 MPa
  • Yield strength: approximately 950–1150 MPa
  • Elongation: approximately 12–16%
  • Hardness: approximately 28–32 HRC
  • Density: approximately 7.85 g/cm³
  • Typical hardness as received: approximately 285–321 HB

Machining behavior

4140 pre-hard is more demanding than low-carbon steel but usually more manageable than many stainless steels, titanium alloys, and nickel alloys. It can machine well with the right tooling and strategy, but hardness increases cutting forces, tool wear, and heat. Because it is already in a harder condition, 4140 pre-hard can reduce post-machining heat treat distortion concerns, but it may increase machining effort compared with annealed material.

Microstructure and phase relevance

4140 pre-hard contains ferrite, pearlite, carbides, and other constituents. Practically, the relevant point is that 4140 pre-hard has a strength and hardness condition that directly shapes machining behavior and functional performance. Its microstructure supports toughness and mechanical performance, but the pre-hard condition means the material should be approached as a performance steel, not mild steel.

Manufacturing implications

4140 pre-hard is often a practical choice for parts that need strength, toughness, wear resistance, and dimensional predictability. Manufacturing implications include higher cutting forces, more tool wear than softer steels, and greater need for stable setups when tolerances are tight.

When this material is a strong fit

4140 pre-hard is a strong fit when the part needs strength, toughness, wear resistance, and dimensional predictability without relying heavily on post-machining heat treatment.

When to be careful

Be careful when the part combines tight tolerances, deep features, long-reach tooling, or small internal radii. The material is machinable, but its hardness and strength can amplify process risk in difficult geometry.

Ti-6Al-4V

Titanium Alloy Grade 5

Short thesis

Ti-6Al-4V is a high-performance titanium alloy used when strength-to-weight ratio, corrosion resistance, fatigue behavior, and aerospace or biomedical compatibility justify the added machining difficulty.

Material identity

Ti-6Al-4V is a titanium alloy commonly known as Grade 5 titanium. Titanium is the balance element, with aluminum and vanadium as the major alloying additions.

Why engineers use it

  • Excellent strength-to-weight ratio
  • Corrosion resistance
  • Excellent fatigue resistance
  • Aerospace and defense-grade performance
  • Biomedical implant compatibility
  • Lower density than steels and nickel alloys

Composition notes

Aluminum is typically around 5.5–6.75 wt%, and vanadium is typically around 3.5–4.5 wt%, with titanium as the balance element. Oxygen, iron, carbon, nitrogen, hydrogen, and other elements are controlled in small amounts. Aluminum and vanadium help define the alloy’s alpha-beta titanium behavior and support the strength, stability, and service performance that make Ti-6Al-4V so widely used.

Mechanical behavior

  • Tensile strength: approximately 895 MPa
  • Yield strength: approximately 825 MPa
  • Elongation: approximately 10%
  • Hardness: approximately 36 HRC
  • Density: approximately 4.43 g/cm³
  • Melting range: approximately 1600–1660°C

Machining behavior

Ti-6Al-4V is difficult to machine compared with aluminum and most steels. It has low thermal conductivity, tends to concentrate heat at the cutting zone, and can be reactive with tooling under poor cutting conditions. The primary machining concerns are heat concentration, tool wear, poor chip evacuation consequences, workholding stability, surface integrity, long cycle times, and conservative cutting strategy.

Microstructure and phase relevance

Ti-6Al-4V is mostly alpha HCP titanium with beta BCC as the secondary phase. Practically, this alpha-beta structure explains why Ti-6Al-4V offers a strong combination of strength, toughness, fatigue behavior, and corrosion resistance. The phase balance matters because titanium’s behavior is strongly connected to processing history, heat, and surface condition.

Manufacturing implications

Ti-6Al-4V can significantly increase manufacturing cost. The material itself is expensive, machining time is longer, tool wear is higher, and process development matters more. These costs can be justified when weight, strength, corrosion, or biomedical compatibility are core requirements.

When this material is a strong fit

Ti-6Al-4V is a strong fit for aerospace, defense, robotics, medical, and high-performance components where low weight and high strength are both needed.

When to be careful

Be careful when a part has thin walls, deep pockets, small internal radii, tight surface finish requirements, or long-reach features. Those geometry drivers can compound titanium’s already difficult machining behavior.

Inconel 625

Nickel-Chromium-Molybdenum-Niobium Alloy

Short thesis

Inconel 625 is a nickel-chromium-molybdenum-niobium alloy used when corrosion resistance, oxidation resistance, high-temperature durability, and extreme-environment reliability justify difficult machining and higher material cost.

Material identity

Inconel 625 is a nickel-based alloy intended for corrosive and high-performance environments where ordinary stainless steels do not provide enough resistance.

Why engineers use it

  • Excellent pitting and crevice corrosion resistance
  • Resistance to chlorides and reducing acids
  • High resistance to stress corrosion cracking
  • Oxidation resistance at elevated temperatures
  • Chemical processing, marine, aerospace, and power generation relevance
  • Reliable performance in extreme environments

Composition notes

Nickel is the balance element, with chromium typically around 20.0–23.0 wt%, molybdenum around 8.0–10.0 wt%, and niobium plus tantalum around 3.15–4.15 wt%. Iron, manganese, silicon, carbon, phosphorus, sulfur, aluminum, titanium, and cobalt are controlled at lower levels. Chromium and molybdenum are central to the alloy’s corrosion and oxidation behavior, while niobium contributes strengthening and stability.

Mechanical behavior

  • Tensile strength: approximately 760 MPa
  • Yield strength: approximately 380 MPa
  • Elongation: approximately 35%
  • Hardness: ≤ 250 HB
  • Density: approximately 8.44 g/cm³
  • Melting range: approximately 1290–1350°C

Machining behavior

Inconel 625 is difficult to machine. It is strong, ductile, heat resistant, and work-hardening-prone. It resists the cutting process in the same way it resists harsh service environments. Key machining concerns include high cutting forces, heat concentration, work hardening, tool wear, notching, burr formation, slower material removal rates, and demanding coolant and chip control.

Microstructure and phase relevance

Inconel 625 is mostly gamma FCC, with delta phase, MC carbides, and other constituents. The practical takeaway is that Inconel 625 maintains useful performance in environments where many materials degrade, but that same stability makes machining more difficult.

Manufacturing implications

Inconel 625 often increases material cost, tooling cost, cycle time, and process risk. The alloy is usually justified when service conditions demand its corrosion and temperature performance. Manufacturing implications include conservative cutting strategies, rigid workholding, high-performance tooling, controlled tool wear, careful attention to burrs and surface integrity, and longer lead times than aluminum, steel, or many stainless alloys.

When this material is a strong fit

Inconel 625 is a strong fit for marine, chemical processing, aerospace, energy, and other environments where corrosion and temperature resistance dominate the material decision.

When to be careful

Be careful when a design includes tight tolerances, thin walls, small radii, deep pockets, or high surface-finish expectations. These features can make an already difficult alloy significantly more demanding.

Inconel 718

Nickel-Chromium Superalloy

Short thesis

Inconel 718 is a nickel-based superalloy used when high-temperature strength, corrosion resistance, oxidation resistance, creep resistance, and aerospace-grade performance are central to the part’s function.

Material identity

Inconel 718 is a nickel-chromium superalloy with a performance envelope intended for demanding temperature and stress environments.

Why engineers use it

  • High-temperature strength
  • Corrosion resistance
  • Oxidation resistance
  • Creep resistance
  • Aerospace and turbine relevance
  • Excellent strength retention compared with conventional alloys

Composition notes

Nickel is typically around 50.0–55.0 wt%, chromium around 17.0–21.0 wt%, iron is a major balance element, niobium plus tantalum are typically around 4.75–5.50 wt%, molybdenum around 2.80–3.30 wt%, titanium around 0.65–1.15 wt%, and aluminum around 0.20–0.80 wt%. Niobium, titanium, and aluminum additions are important because precipitation strengthening is central to 718’s performance.

Mechanical behavior

  • Tensile strength: approximately 1240 MPa
  • Yield strength: approximately 1030 MPa
  • Elongation: approximately 18%
  • Hardness: approximately 39 HRC
  • Density: approximately 8.19 g/cm³
  • Melting range: approximately 1260–1335°C

Machining behavior

Inconel 718 is very difficult to machine. It combines high strength, heat resistance, work-hardening tendency, and abrasive/tool-wearing behavior. The machining process typically requires rigid setups, controlled engagement, premium tooling, and conservative process assumptions. Machining concerns include high cutting forces, severe tool wear, work hardening, heat concentration, surface integrity concerns, slow material removal, notching and edge wear, and high cost of process mistakes.

Microstructure and phase relevance

Inconel 718 is a precipitation-strengthened superalloy. It is commonly associated with a gamma FCC matrix and strengthening precipitates, especially gamma double prime / Ni₃Nb, with gamma prime also present. Delta phase and carbides can also be relevant depending on condition and processing. Practically, this microstructure supports high-temperature strength but also contributes to difficult machining.

Manufacturing implications

Inconel 718 can dramatically increase cost and lead time. It is not a material to specify casually. When function requires it, the manufacturing plan must account for slow cutting, tool wear, heat, inspection, and process stability.

When this material is a strong fit

Inconel 718 is a strong fit for high-temperature, high-stress, aerospace, defense, turbine, and severe-service components where conventional alloys cannot survive the required environment.

When to be careful

Be careful when 718 is specified without a clear service requirement. If the part does not need high-temperature strength, creep resistance, or severe-environment performance, the cost and machining difficulty may not be justified.

Hastelloy C-276

Nickel-Molybdenum-Chromium Alloy

Short thesis

Hastelloy C-276 is a nickel-molybdenum-chromium alloy used when corrosion resistance in extreme chemical environments is the primary requirement and difficult machining is accepted as part of the tradeoff.

Material identity

Hastelloy C-276 is a nickel-based corrosion-resistant alloy designed for demanding corrosive environments, including chemical processing, marine and offshore applications, pulp and paper, pollution control, and nuclear-related environments.

Why engineers use it

  • Exceptional corrosion resistance
  • Resistance to pitting, crevice corrosion, and stress corrosion cracking
  • Resistance to oxidizing and reducing media
  • Chemical processing suitability
  • Marine and offshore use
  • Extreme-environment reliability

Composition notes

Nickel is the balance element, with molybdenum typically around 15.0–17.0 wt%, chromium around 14.5–16.5 wt%, iron around 4.0–7.0 wt%, and tungsten around 3.0–4.5 wt%. Cobalt, manganese, vanadium, silicon, carbon, phosphorus, and sulfur are controlled in smaller amounts. Molybdenum and chromium are central to the alloy’s corrosion performance.

Mechanical behavior

  • Tensile strength: approximately 690 MPa
  • Yield strength: approximately 283 MPa
  • Elongation: approximately 40%
  • Hardness: approximately 22–24 HRC
  • Density: approximately 8.89 g/cm³
  • Melting range: approximately 1370–1425°C

Machining behavior

Hastelloy C-276 is difficult to machine. It is tough, corrosion resistant, and prone to work hardening. Cutting conditions, tool geometry, coolant delivery, and stable workholding are important. Machining concerns include work hardening, high tool wear, heat generation, tough chip formation, burr formation, slower material removal, surface finish sensitivity, and high cost of scrap or rework.

Microstructure and phase relevance

Hastelloy C-276 is primarily a gamma FCC structure with carbides and other phases. Practically, the microstructure supports the alloy’s corrosion resistance and durability, while also contributing to machining difficulty. The important manufacturing point is that C-276 is not chosen for convenience. It is chosen because the environment demands it.

Manufacturing implications

C-276 adds cost through raw material price, slower machining, tooling demands, and inspection expectations. It is often justified when failure by corrosion would be unacceptable. Manufacturing implications include premium tooling, conservative material removal, strong burr and edge-control planning, and extra attention to surface finish and chemical-service surfaces.

When this material is a strong fit

C-276 is a strong fit when the application involves aggressive chemical exposure, marine/offshore conditions, corrosion-critical systems, or service environments where ordinary stainless alloys are not sufficient.

When to be careful

Be careful when the part geometry includes small internal radii, deep pockets, tight surface finish, or thin walls. Those features can significantly increase machining cost and process risk in C-276.

PEEK

Polyether Ether Ketone

Short thesis

PEEK is a high-performance engineering polymer used when chemical resistance, temperature capability, low weight, wear resistance, and tight-tolerance polymer machining are more important than metal-like strength or conductivity.

Material identity

PEEK stands for polyether ether ketone. It is a high-performance semi-crystalline engineering polymer used in medical, aerospace, semiconductor, chemical, electrical, and precision mechanical applications.

Why engineers use it

  • Exceptional chemical resistance
  • High-temperature performance
  • High strength and stiffness for a polymer
  • Low weight
  • Excellent wear resistance
  • Biocompatibility and outgassing resistance
  • Low moisture absorption
  • Flame retardance

Composition notes

Typical elemental composition is approximately 76.20 wt% carbon, 5.80 wt% hydrogen, 17.60 wt% oxygen, and 0.40 wt% nitrogen. Unlike metal alloys, PEEK is not interpreted primarily through metallic alloying elements. Its performance is better understood through polymer structure, crystallinity, temperature behavior, and grade formulation.

Mechanical behavior

  • Tensile strength: approximately 100 MPa
  • Flexural strength: approximately 150 MPa
  • Elongation at break: approximately 35%
  • Flexural modulus: approximately 3.6 GPa
  • Izod impact strength: no break, notched
  • Density: approximately 1.30 g/cm³
  • Melting point: approximately 343°C
  • Continuous service temperature: approximately 250°C

Machining behavior

PEEK machines very differently from metals. It can be machined to tight tolerances, but heat control, fixturing, burr behavior, and material movement matter. The material may deflect, move, or respond to heat differently than metallic parts. Machining concerns include heat buildup, burrs and edge condition, part movement, tool sharpness, clamping pressure, surface finish expectations, and dimensional stability after machining.

Microstructure and phase relevance

PEEK is semi-crystalline, with a practical balance of crystalline and amorphous regions. Crystallinity influences stiffness, chemical resistance, thermal behavior, and dimensional stability. For manufacturing, the grade and condition of PEEK should be understood before assuming one polymer behaves like another.

Manufacturing implications

PEEK is expensive compared with common plastics, but it can solve problems metals or lower-grade polymers cannot. It is a strong candidate for chemically resistant, lightweight, wear-resistant, electrically useful, or biocompatible components. Manufacturing implications include avoiding excessive heat, using sharp tools and stable support, controlling clamping forces, planning for burr and edge quality, and treating grade selection as part of the design.

When this material is a strong fit

PEEK is a strong fit when the part needs high-performance polymer behavior, chemical resistance, high service temperature, low moisture absorption, wear resistance, or biocompatibility.

When to be careful

Be careful when the design assumes PEEK behaves like metal. It can hold tight tolerances, but stiffness, thermal expansion, clamping response, and surface behavior need to be considered.