1. Basic Concept of Non-Ferrous Metals
Non-ferrous metals are metallic materials in which iron is not the principal constituent.
Strictly speaking, this does not mean that non-ferrous metals contain no iron at all. Some non-ferrous alloys may contain small amounts of iron, but they are distinguished from steels because their basic properties are governed by metals such as aluminum, copper, magnesium, titanium, nickel, or zinc rather than iron.
In mechanical design, non-ferrous metals are used for the following purposes:
Weight reduction
Improvement of corrosion resistance
Provision of thermal conductivity
Provision of electrical conductivity
Non-magnetic performance
Improvement of friction and bearing performance
High-temperature capability
Resistance to special chemical environments
Improvement of appearance and surface quality
Improvement of castability and formability
Non-ferrous metals are generally more expensive than steels, but they offer unique advantages in density, corrosion resistance, conductivity, castability, and high-temperature performance that are difficult to achieve with steel.
2. Major Classification of Non-Ferrous Metals
Non-ferrous metals commonly used in mechanical design can be classified as follows:
Aluminum and aluminum alloys
Copper and copper alloys
Magnesium and magnesium alloys
Titanium and titanium alloys
Nickel and nickel alloys
Zinc and zinc alloys
Tin- and lead-based alloys
Other special non-ferrous metals
Each material group differs significantly in density, strength, corrosion resistance, thermal conductivity, weldability, castability, and cost.
3. Roles of Major Alloying Elements
The mechanical properties of non-ferrous metals are strongly influenced by the type and amount of alloying elements rather than by the base metal alone.
3.1 Silicon — Si
Main functions:
Improves the castability of aluminum alloys
Increases molten-metal fluidity
Reduces casting shrinkage and thermal expansion
Can improve wear resistance
Excessive amounts may reduce ductility and machinability
The high silicon content of aluminum die-casting alloys improves the ability of molten metal to fill complex dies.
3.2 Magnesium — Mg
Main functions:
Increases the strength of aluminum alloys
Enhances work-hardening response
Can improve corrosion resistance
Combines with silicon to form Mg₂Si precipitates
Contributes to the strengthening of heat-treatable aluminum alloys
Magnesium is an important alloying element in 5000- and 6000-series aluminum alloys.
3.3 Copper — Cu
Main functions:
Increases the strength and heat-treatability of aluminum alloys
Enables age hardening
Improves elevated-temperature strength
Controls strength and machinability in brass when combined with zinc
Excessive copper may reduce the corrosion resistance of aluminum alloys
The high strength of 2000-series aluminum alloys is mainly produced by copper addition and age hardening.
3.4 Zinc — Zn
Main functions:
Provides high strength in aluminum alloys
Produces strong age-hardening effects when combined with magnesium
Forms brass when alloyed with copper
Improves castability and dimensional accuracy in die-casting alloys
7000-series aluminum alloys achieve very high strength through zinc and magnesium additions.
3.5 Manganese — Mn
Main functions:
Improves the strength and corrosion resistance of aluminum alloys
Refines the grain structure
Reduces the harmful effects of iron impurities
Increases strength through solid-solution strengthening
Manganese is the principal alloying element in 3000-series aluminum alloys.
3.6 Tin — Sn
Main functions:
Improves corrosion resistance and bearing performance in copper alloys
Increases the strength and wear resistance of bronze
Improves solderability and joining performance
Forms low-melting-point alloys
Tin bronze is used for bearings, bushings, and worm gears because of its good wear resistance and corrosion resistance.
3.7 Nickel — Ni
Main functions:
Improves corrosion resistance in copper and nickel alloys
Improves high-temperature strength
Stabilizes the structure of titanium alloys and superalloys
Improves resistance to chemical and seawater environments
3.8 Chromium — Cr
Functions in non-ferrous alloys:
Improves oxidation resistance and high-temperature corrosion resistance in nickel alloys
Increases strength and wear resistance in copper alloys
Improves grain structure and stress-corrosion resistance in some aluminum alloys
3.9 Iron — Fe
In non-ferrous metals, iron is generally present as an impurity or secondary alloying element.
Effects:
In aluminum, excessive iron can form brittle intermetallic compounds.
In copper, iron can reduce electrical conductivity.
In nickel alloys, iron may be used to stabilize structure and control cost.
In titanium, iron increases strength but may reduce ductility and corrosion resistance.
4. Aluminum and Aluminum Alloys
4.1 Basic Characteristics
Aluminum is one of the most widely used non-ferrous metals in mechanical design.
Main characteristics:
Density of approximately 2.7 g/cm³, about one-third that of steel
Relatively good corrosion resistance
Good thermal and electrical conductivity
Suitable for machining, extrusion, rolling, and casting
Naturally forms an oxide film
Can be anodized
Lower elastic modulus than steel
Rapid loss of strength at elevated temperature
Aluminum is not merely a lightweight metal. It is a material that combines low mass, corrosion resistance, machinability, and thermal conductivity.
4.2 Classification of Aluminum Alloy Series
Wrought aluminum alloys are generally classified as follows:
Series | Main Alloying Element | Representative Characteristics |
|---|---|---|
1000 series | Nearly pure aluminum | High conductivity, excellent corrosion resistance |
2000 series | Cu | High strength, lower corrosion resistance |
3000 series | Mn | Good formability, medium strength |
4000 series | Si | Low melting point, welding and casting applications |
5000 series | Mg | Excellent corrosion resistance and weldability |
6000 series | Mg-Si | Balanced strength, machinability, and corrosion resistance |
7000 series | Zn-Mg | Very high strength |
8000 series | Other elements | Special applications |
4.3 Commercially Pure Aluminum — A1050
Representative Chemical Composition
Element | Typical Content, wt.% |
|---|---|
Al | 99.50 min. |
Fe | 0.40 max. |
Si | 0.25 max. |
Cu | 0.05 max. |
Mn | 0.05 max. |
Mg | 0.05 max. |
Zn | 0.05 max. |
Ti | 0.03 max. |
Relationship Between Composition and Properties
Because of its high aluminum purity, A1050 exhibits:
High electrical conductivity
High thermal conductivity
Good corrosion resistance
Excellent formability
Low strength and hardness
A tendency to adhere to cutting tools during machining
Iron and silicon are present as impurities. As their content increases, strength may rise slightly, while conductivity and ductility may decrease.
Main Applications
Electrical conductors
Heat sinks
Chemical containers
Reflectors
Covers
Decorative panels
Heat-exchanger fins
4.4 A5052
A5052 is a 5000-series aluminum alloy with magnesium as its principal alloying element.
Representative Chemical Composition
Element | Typical Range, wt.% |
|---|---|
Mg | 2.2–2.8 |
Cr | 0.15–0.35 |
Fe | 0.40 max. |
Si | 0.25 max. |
Cu | 0.10 max. |
Mn | 0.10 max. |
Zn | 0.10 max. |
Al | Balance |
Relationship Between Composition and Properties
Magnesium
Magnesium dissolves into the aluminum crystal lattice and increases strength and work-hardening capacity.
Magnesium improves:
Strength
Corrosion resistance
Resistance to marine environments
Retained strength after welding
Sheet-metal formability
Chromium
Chromium helps stabilize grain structure and corrosion resistance and contributes to reducing stress-corrosion susceptibility.
Mechanical Characteristics
Medium strength
Excellent corrosion resistance
Good weldability
Good sheet-metal bending performance
Not heat-treatable
Strength can be increased by cold working
Main Applications
Machine covers
Sheet-metal frames
Non-contact parts in food machinery
Marine structures
Fuel tanks
Cases
Brackets
4.5 A6061
A6061 is a representative 6000-series heat-treatable alloy containing magnesium and silicon as its principal alloying elements.
Representative Chemical Composition
Element | Typical Range, wt.% |
|---|---|
Mg | 0.8–1.2 |
Si | 0.4–0.8 |
Cu | 0.15–0.40 |
Cr | 0.04–0.35 |
Fe | 0.70 max. |
Mn | 0.15 max. |
Zn | 0.25 max. |
Ti | 0.15 max. |
Al | Balance |
Relationship Between Composition and Properties
Magnesium and Silicon
Magnesium and silicon combine to form Mg₂Si precipitates.
After solution heat treatment and aging, fine Mg₂Si particles impede dislocation movement and increase strength.
Copper
Copper improves strength and age-hardening response, but higher copper content may slightly reduce corrosion resistance.
Chromium
Chromium stabilizes grain structure and toughness.
Mechanical Characteristics
Good balance of strength and machinability
Good machinability
Excellent extrudability
Relatively good weldability
Good corrosion resistance
High strength in the T6 condition
Strength may decrease in the weld heat-affected zone
Main Applications
Machine frames
Aluminum profiles
Robotic structures
Jigs
Bases
Plates
Shaft housings
Automation equipment
4.6 A7075
A7075 is a high-strength 7000-series alloy containing zinc and magnesium as its principal alloying elements.
Representative Chemical Composition
Element | Typical Range, wt.% |
|---|---|
Zn | 5.1–6.1 |
Mg | 2.1–2.9 |
Cu | 1.2–2.0 |
Cr | 0.18–0.28 |
Fe | 0.50 max. |
Si | 0.40 max. |
Mn | 0.30 max. |
Ti | 0.20 max. |
Al | Balance |
Relationship Between Composition and Properties
Zinc and Magnesium
Zinc and magnesium form MgZn₂-type precipitates, producing a strong age-hardening effect.
Copper
Copper further increases strength and elevated-temperature performance.
Chromium
Chromium improves grain structure and resistance to stress-corrosion cracking.
Mechanical Characteristics
Very high strength
High fatigue strength
Low density
Good machinability
Poor weldability
Lower corrosion resistance than 6061
Susceptible to stress-corrosion cracking
High cost
Main Applications
Aircraft structures
High-strength jigs
Lightweight robotic arms
Highly loaded aluminum components
Mold plates
Precision structural parts
4.7 ADC12 Aluminum Die-Casting Alloy
ADC12 is a widely used Al-Si-Cu die-casting alloy.
Representative Chemical Composition
Element | Typical Range, wt.% |
|---|---|
Si | 9.6–12.0 |
Cu | 1.5–3.5 |
Fe | 1.3 max. |
Mn | 0.5 max. |
Mg | 0.3 max. |
Zn | 1.0 max. |
Ni | 0.5 max. |
Sn | 0.3 max. |
Al | Balance |
Relationship Between Composition and Properties
High Silicon Content
Improves molten-metal fluidity
Supports casting of complex shapes
Reduces shrinkage
Improves wear resistance
Copper
Increases strength and hardness
Improves machinability
May reduce corrosion resistance
Iron
Iron reduces die soldering, but excessive amounts can form brittle intermetallic compounds.
Mechanical Characteristics
Excellent castability
Suitable for complex thin-wall parts
Good dimensional accuracy
Good machinability
Limited weldability and ductility
Lower fatigue strength and toughness than wrought alloys
Internal porosity may be present
Main Applications
Motor housings
Gearbox cases
Electronic housings
Automotive parts
Pump cases
Complex machine covers
5. Copper and Copper Alloys
5.1 Basic Characteristics
Copper is a major non-ferrous metal with excellent electrical and thermal conductivity.
Main characteristics:
Very high electrical conductivity
Excellent thermal conductivity
Good corrosion resistance
Good ductility and formability
Antimicrobial properties
High density of approximately 8.9 g/cm³
Low strength in the pure state
Strength and wear resistance can be increased through alloying
5.2 Pure Copper — C1100
Representative Chemical Composition
Element | Typical Content, wt.% |
|---|---|
Cu | 99.90 min. |
O | Approximately 0.02–0.05 |
Other elements | Trace |
Composition and Properties
The high copper purity provides excellent electrical and thermal conductivity.
A small amount of oxygen may be present as Cu₂O. Heating in a hydrogen atmosphere can cause hydrogen embrittlement.
Mechanical Characteristics
Low strength
High ductility
Excellent conductivity
Good formability
Good solderability
Poor machinability
Can be work-hardened
Main Applications
Electrical terminals
Busbars
Cables
Heat-transfer components
Heat exchangers
Electrodes
Grounding components
5.3 Brass — C2600 Series
Brass is an alloy of copper and zinc.
Representative Chemical Composition
Element | Typical Range, wt.% |
|---|---|
Cu | Approximately 68.5–71.5 |
Zn | Balance, approximately 28.5–31.5 |
Pb | Trace |
Fe | Trace |
Relationship Between Composition and Properties
Zinc
Zinc is less expensive than copper and produces the following effects when added to copper:
Increased strength
Increased hardness
Changes in machinability and formability
Reduced material cost
Change in color
As zinc content increases, strength generally rises, while ductility and corrosion resistance may decrease depending on composition and environment.
Mechanical Characteristics
Higher strength than pure copper
Good formability
Attractive appearance
Good corrosion resistance
Free-cutting grades have excellent machinability
Susceptible to stress-corrosion cracking in ammonia environments
Main Applications
Fittings
Valve components
Terminals
Screws
Decorative parts
Sensor components
Precision-machined parts
5.4 Free-Cutting Brass — C3604
Representative Chemical Composition
Element | Typical Range, wt.% |
|---|---|
Cu | Approximately 57–61 |
Pb | Approximately 1.8–3.7 |
Fe | 0.5 max. |
Zn | Balance |
Relationship Between Composition and Properties
Lead
Lead has very low solubility in the copper-zinc matrix and exists as fine particles.
During machining, these lead particles help break chips and reduce tool friction, producing excellent machinability.
However, lead use may be restricted for environmental, food-contact, and drinking-water applications.
Mechanical Characteristics
Excellent machinability
Good dimensional accuracy
Suitable for thread cutting
Limited cold formability
Limited weldability
Lead-free brass should be considered for food or drinking-water contact
Main Applications
Valves
Fittings
Precision screws
Connectors
Nozzles
Automatic-lathe components
5.5 Tin Bronze — CAC406 or Similar Grades
Tin bronze is a copper alloy containing tin as a principal alloying element.
Representative Chemical Composition Example
Element | Typical Range, wt.% |
|---|---|
Cu | Approximately 83–87 |
Sn | Approximately 4–6 |
Zn | Approximately 4–6 |
Pb | Approximately 4–6 |
Other elements | Trace |
Actual composition varies significantly by grade.
Relationship Between Composition and Properties
Tin
Increases strength and hardness
Improves corrosion and wear resistance
Improves seawater performance
Lead
Improves lubricity
Improves bearing performance
Improves machinability
May reduce impact strength
Zinc
Improves castability and molten-metal fluidity and helps control cost.
Mechanical Characteristics
Excellent wear resistance
Good sliding properties
Good corrosion resistance
Relatively high load-carrying capacity
Lower conductivity than pure copper
High cost
Main Applications
Bushings
Sleeve bearings
Worm wheels
Valves
Pump impellers
Marine components
5.6 Aluminum Bronze
Aluminum bronze is a high-strength copper alloy containing aluminum.
Representative Chemical Composition Example
Element | Typical Range, wt.% |
|---|---|
Cu | Approximately 80–90 |
Al | Approximately 8–12 |
Fe | Approximately 1–5 |
Ni | 0–5 depending on grade |
Mn | Small amount |
Relationship Between Composition and Properties
Aluminum
Provides strong solid-solution strengthening in the copper matrix and forms a stable aluminum oxide film on the surface.
Iron and Nickel
Refine the microstructure and improve strength, corrosion resistance, and erosion resistance.
Mechanical Characteristics
High strength among copper alloys
Excellent seawater corrosion resistance
Good wear and cavitation resistance
Non-sparking behavior
Lower machinability than brass
Main Applications
Seawater pumps
Propellers
Valves
Worm gears
Heavy-duty bushings
Explosion-safe tools
5.7 Beryllium Copper
Beryllium copper is a precipitation-hardening copper alloy that combines high strength with useful electrical conductivity.
Representative Chemical Composition
Element | Typical Range, wt.% |
|---|---|
Be | Approximately 1.8–2.0 |
Co + Ni | Approximately 0.2–0.6 |
Cu | Balance |
Relationship Between Composition and Properties
Beryllium forms fine precipitates after heat treatment, significantly increasing strength.
Cobalt and nickel control precipitation behavior and grain structure.
Mechanical Characteristics
Very high strength
High fatigue strength
Good electrical conductivity
Excellent spring properties
Non-sparking behavior
Good wear resistance
High cost
Requires strict control of beryllium dust during processing
Main Applications
Spring contacts
Precision terminals
Mold components
Non-sparking tools
Sensor springs
High-load electrical contacts
6. Magnesium and Magnesium Alloys
6.1 Basic Characteristics
Magnesium is one of the lightest practical structural metals.
Its density is approximately 1.74 g/cm³, making it about 35% lighter than aluminum.
Main characteristics:
Very low density
Excellent machinability
Good vibration damping
Suitable for die casting
Low elastic modulus
Limited corrosion resistance
Limited elevated-temperature strength
Fire risk from powder and machining chips
6.2 AZ91D
AZ91D is a representative magnesium die-casting alloy.
Representative Chemical Composition
Element | Typical Range, wt.% |
|---|---|
Al | 8.3–9.7 |
Zn | 0.35–1.0 |
Mn | 0.15–0.50 |
Si | 0.10 max. |
Cu | 0.030 max. |
Ni | 0.002 max. |
Fe | 0.005 max. |
Mg | Balance |
Relationship Between Composition and Properties
Aluminum
Increases strength and castability
Improves corrosion resistance
Increases hardness
Zinc
Improves strength and castability
Excessive content may adversely affect corrosion resistance and hot-cracking behavior
Manganese
Combines with iron impurities and reduces their harmful effect on corrosion resistance.
Mechanical Characteristics
Very low weight
Excellent castability
Good vibration damping
Excellent machinability
Limited impact toughness
Poor creep performance at elevated temperature
Susceptible to galvanic corrosion
Main Applications
Electronic housings
Automotive housings
Lightweight machine covers
Portable equipment
Gearbox cases
Robotic components
7. Titanium and Titanium Alloys
7.1 Basic Characteristics
Titanium offers an excellent strength-to-weight ratio and outstanding corrosion resistance.
Main characteristics:
Density of approximately 4.5 g/cm³
High specific strength
Excellent corrosion resistance
Good resistance to seawater and chloride environments
Excellent biocompatibility
Non-magnetic
Low thermal conductivity
Low elastic modulus
Difficult machining and forming
High cost
7.2 Commercially Pure Titanium Grade 2
Representative Chemical Composition
Element | Typical Content, wt.% |
|---|---|
Ti | Balance |
Fe | 0.30 max. |
O | 0.25 max. |
C | 0.08 max. |
N | 0.03 max. |
H | 0.015 max. |
Relationship Between Composition and Properties
Oxygen
Oxygen is a strong solid-solution strengthening element in titanium.
As oxygen content increases:
Strength increases
Hardness increases
Ductility decreases
Impact toughness decreases
Iron
Iron increases strength, but excessive amounts may reduce ductility and corrosion resistance.
Mechanical Characteristics
Medium strength
Excellent corrosion resistance
Good formability
Excellent weldability
Non-magnetic
Low thermal conductivity
Main Applications
Chemical tanks
Heat exchangers
Seawater piping
Medical devices
Food and pharmaceutical equipment
Components in corrosive environments
7.3 Ti-6Al-4V, Grade 5
Representative Chemical Composition
Element | Typical Range, wt.% |
|---|---|
Al | 5.5–6.75 |
V | 3.5–4.5 |
Fe | 0.40 max. |
O | 0.20 max. |
C | 0.08 max. |
N | 0.05 max. |
H | 0.015 max. |
Ti | Balance |
Relationship Between Composition and Properties
Aluminum
Stabilizes the alpha phase and increases elevated-temperature strength and stiffness.
Vanadium
Stabilizes the beta phase and adjusts heat-treatability and the strength-toughness balance.
Oxygen
Increases strength through solid-solution strengthening but reduces ductility.
Mechanical Characteristics
Very high specific strength
High fatigue strength
Excellent corrosion resistance
Heat-treatable
Difficult to machine
Susceptible to galling under friction
Lower elastic modulus than steel
High cost
Main Applications
Aircraft components
High-strength lightweight shafts
Medical implants
Robotic components
High-performance fasteners
Chemical equipment
8. Nickel and Nickel Alloys
8.1 Basic Characteristics
Nickel alloys are used in high-temperature, high-pressure, and highly corrosive chemical environments.
Main characteristics:
Excellent high-temperature strength
Excellent oxidation resistance
Excellent corrosion resistance
Excellent creep resistance
Good thermal-fatigue performance
High cost
Poor machinability
High cutting forces
8.2 Inconel 625
Representative Chemical Composition
Element | Typical Range, wt.% |
|---|---|
Ni | Approximately 58 min. |
Cr | 20–23 |
Mo | 8–10 |
Nb + Ta | 3.15–4.15 |
Fe | 5 max. |
Co | 1 max. |
C | 0.10 max. |
Mn | 0.5 max. |
Si | 0.5 max. |
Relationship Between Composition and Properties
Nickel
Forms the matrix and stabilizes the structure under high-temperature and corrosive conditions.
Chromium
Improves oxidation resistance and high-temperature corrosion resistance.
Molybdenum
Improves corrosion resistance in reducing acids and chloride environments.
Niobium
Increases strength through solid-solution and precipitation strengthening.
Mechanical Characteristics
Excellent elevated-temperature strength
Very high corrosion resistance
Good seawater resistance
Relatively good weldability
Strong work hardening
Very poor machinability
High cost
Main Applications
Chemical equipment
Marine piping
High-temperature ducts
Turbine components
Heat exchangers
High-temperature fasteners
8.3 Hastelloy C-276
Representative Chemical Composition
Element | Typical Range, wt.% |
|---|---|
Ni | Balance, approximately 50 min. |
Mo | 15–17 |
Cr | 14.5–16.5 |
Fe | 4–7 |
W | 3–4.5 |
Co | 2.5 max. |
C | 0.01 max. |
Relationship Between Composition and Properties
High Molybdenum Content
Improves resistance to strongly reducing environments and crevice corrosion.
Chromium
Provides resistance to oxidizing environments.
Tungsten
Improves localized corrosion resistance and high-temperature strength.
Low Carbon Content
Reduces carbide precipitation and the risk of intergranular corrosion in welded areas.
Main Applications
Strong-acid equipment
Chemical reactors
Waste-gas treatment systems
Corrosive piping
Pharmaceutical and chemical production equipment
9. Zinc and Zinc Alloys
9.1 Basic Characteristics
Zinc is characterized by corrosion resistance, excellent castability, and a low melting point.
Main characteristics:
Excellent die-casting performance
Suitable for precise shapes
Good surface quality
Used as a sacrificial coating for steel
Relatively high density
Low elevated-temperature strength
Susceptible to creep under sustained loading
9.2 ZDC2 or Zamak 3 Series
Representative Chemical Composition
Element | Typical Range, wt.% |
|---|---|
Al | Approximately 3.5–4.3 |
Mg | Approximately 0.02–0.06 |
Cu | Approximately 0.25 max. |
Fe | Approximately 0.10 max. |
Zn | Balance |
Relationship Between Composition and Properties
Aluminum
Increases strength, hardness, and molten-metal fluidity.
Magnesium
Suppresses intergranular corrosion and stabilizes the microstructure.
Copper
Improves strength and wear resistance but may affect dimensional stability and corrosion behavior.
Mechanical Characteristics
Excellent die-castability
High dimensional accuracy
Good surface finish
Suitable for thin-wall casting
Good impact performance
Poor high-temperature creep resistance
Relatively heavy
Main Applications
Handles
Levers
Small housings
Precision machine parts
Locking devices
Electronic components
Low-load gears and cams
10. Tin- and Lead-Based Alloys
10.1 Tin-Based Bearing Alloys
Tin-based Babbitt metals are used for sliding bearings.
Representative Composition Example
Element | Typical Range, wt.% |
|---|---|
Sn | Approximately 80–90 |
Sb | Approximately 7–12 |
Cu | Approximately 3–8 |
Relationship Between Composition and Properties
Tin
Provides a soft matrix and corrosion resistance.
Antimony
Increases hardness and load-carrying capacity.
Copper
Forms hard intermetallic compounds and improves wear resistance and fatigue strength.
Mechanical Characteristics
Excellent conformability
Good embeddability
Low friction
Reduced shaft damage
Limited elevated-temperature strength
Suitable as bearing lining material
10.2 Considerations for Lead-Based Alloys
Lead has the following characteristics:
Low melting point
High density
Excellent radiation shielding
Good vibration damping
Low strength
Toxicity and environmental concerns
Lead use is now highly restricted in food, drinking-water, electrical, electronic, and consumer products.
Brass, bronze, and solder containing lead must be reviewed against applicable environmental and product-safety regulations.
11. Comparison of Major Non-Ferrous Metals
Material Group | Density | Strength | Corrosion Resistance | Thermal Conductivity | Processability | Representative Applications |
|---|---|---|---|---|---|---|
Aluminum | Low | Low to very high | Good | High | Good | Frames, covers, housings |
Copper | High | Low to high | Excellent | Very high | Varies by alloy | Electrodes, bushings, heat exchangers |
Magnesium | Very low | Medium | Limited | Medium | Excellent | Lightweight housings |
Titanium | Medium | High | Excellent | Low | Difficult | High-strength and corrosion-resistant parts |
Nickel alloys | High | High | Excellent | Low | Very difficult | High-temperature and chemical equipment |
Zinc alloys | High | Medium | Good | Medium | Excellent castability | Precision die castings |
Tin-based alloys | High | Low | Good | Medium | Good | Bearing linings |
12. Selection of Non-Ferrous Metals by Machine Component
12.1 Lightweight Frames
Recommended materials:
A6061
A6063
A5052
Selection criteria:
Extruded profiles: 6063 or 6061
Machined frames: 6061
Sheet-metal covers and frames: 5052
High-strength lightweight structures: 7075
12.2 Housings
Recommended materials:
ADC12
AZ91D
A6061
ZDC2
Selection criteria:
Complex high-volume parts: ADC12
Ultra-lightweight housings: AZ91D
Precision-machined housings: A6061
Small precision die castings: ZDC2
12.3 Bushings and Sliding Bearings
Recommended materials:
Tin bronze
Leaded bronze
Aluminum bronze
Beryllium copper
Babbitt metal
Selection criteria:
General bushings: Tin bronze
High-load or seawater environments: Aluminum bronze
High conductivity and spring performance: Beryllium copper
Bearing linings: Babbitt metal
12.4 Heat-Transfer Components
Recommended materials:
Pure copper
Aluminum
Commercially pure titanium
Nickel alloys
Selection criteria:
Maximum thermal conductivity: Copper
Lightweight heat dissipation: Aluminum
Seawater or corrosive environments: Titanium
High-temperature chemical environments: Nickel alloys
12.5 Electrical Terminals and Contacts
Recommended materials:
Pure copper
Brass
Beryllium copper
Phosphor bronze
Selection criteria:
Maximum conductivity: Pure copper
Machinability and cost: Brass
Spring performance and conductivity: Beryllium copper
Repeated elasticity and wear resistance: Phosphor bronze
13. Considerations for Non-Ferrous Metals in Food Machinery
In food machinery, non-ferrous metals must be evaluated not only for strength but also for food compatibility, corrosion, metal-ion release, surface damage, and reaction with cleaning chemicals.
13.1 Aluminum
Possible applications:
Non-contact frames
Covers
Housings
Guides
Heat-dissipation components
Considerations:
Can corrode in strong alkaline and acidic environments
Surface-treatment damage must be reviewed for food-contact use
Base metal may become exposed if anodized layers are worn
Corrosion may occur in saline and aggressive cleaning environments
13.2 Copper and Copper Alloys
Possible applications:
Heat exchangers
Electrical components
Non-contact bushings
Certain valves and fittings
Considerations:
Copper ions may leach during direct contact with acidic food
Leaded brass is restricted in food and drinking-water applications
Verdigris and surface corrosion must be controlled
13.3 Titanium
Titanium is advantageous where high corrosion resistance and hygiene are required in food, pharmaceutical, and chemical equipment.
Advantages:
Excellent corrosion resistance
Low metal-ion release
Good chloride resistance
Non-magnetic
Biocompatible
Limitations:
High cost
Difficult machining
Galling and friction problems
Requires suitable supply chains and welding technology
13.4 Lead and Beryllium
Lead:
Should not be used in food-contact areas
Applicable environmental and hygiene regulations must be checked
Beryllium copper:
Finished parts can be stable in service, but dust and fumes generated during processing can be hazardous
Strict safety control is required during machining, grinding, and welding
14. Non-Ferrous Metal Selection Procedure
Non-ferrous metals should be selected in the following order.
14.1 Confirm the Function
Does the part support a structure?
Is weight reduction important?
Must it transfer heat?
Must it conduct electricity?
Is it exposed to friction and wear?
Is it used at high temperature or in a corrosive environment?
Does it contact food?
14.2 Confirm the Load
Tension
Compression
Bending
Torsion
Impact
Repeated fatigue
Contact load
Creep
Because aluminum and magnesium have lower elastic moduli than steel, deflection and vibration must be reviewed in addition to strength.
14.3 Confirm the Environment
Water
Salt
Acids
Alkalis
Seawater
High temperature
Vacuum
Electrochemical contact
Cleaning chemicals
Galvanic corrosion can occur when dissimilar metals are in contact in the presence of an electrolyte.
14.4 Confirm the Manufacturing Process
Machining
Extrusion
Sheet-metal forming
Forging
Casting
Die casting
Welding
Brazing
Heat treatment
Surface treatment
Even within the same aluminum family, wrought and cast products differ significantly in internal structure and fatigue performance.
14.5 Confirm Cost and Availability
Items to review:
Raw-material price
Availability in standard forms
Minimum order quantity
Machining cost
Heat-treatment cost
Surface-treatment cost
Recyclability
Repairability
Equipment service life
A high-performance material is not always the most economical choice.
15. Information to Specify on Drawings and Material Specifications
15.1 Material Grade and Standard
Examples:
JIS H 4000 A5052P-H32
JIS H 4040 A6061BE-T6
ASTM B221 6061-T6
JIS H 3250 C3604
ASTM B348 Titanium Grade 2
ASTM B443 Alloy 625
The product form and heat-treatment condition should be specified together with the material grade.
15.2 Temper or Heat-Treatment Condition
Aluminum examples:
O: Annealed
H32: Strain-hardened and stabilized
T4: Solution heat-treated and naturally aged
T6: Solution heat-treated and artificially aged
The strength and formability of A6061 vary significantly between O, T4, and T6 conditions.
15.3 Surface Treatment
Aluminum:
Anodizing
Hard anodizing
Conversion coating
Painting
Electroless nickel plating
Copper alloys:
Nickel plating
Tin plating
Silver plating
Chromium plating
Titanium:
Pickling
Anodizing
Surface polishing
15.4 Chemical Composition Certificate
For critical components, a mill certificate or material certificate should be reviewed.
Items to verify:
Principal alloying elements
Maximum impurity levels
Heat-treatment condition
Tensile strength
Yield strength
Elongation
Hardness
Product specification
Lot number
16. Final Summary
Non-ferrous metals are not simply lighter or more corrosion-resistant substitutes for steel.
Each non-ferrous metal develops its own mechanical properties through specific alloying elements and microstructures.
Aluminum alloys are classified into sheet-forming, structural, casting, and high-strength grades according to additions of magnesium, silicon, copper, and zinc.
Magnesium increases strength and corrosion resistance.
Silicon improves castability and molten-metal fluidity.
Copper improves strength and age-hardening response.
Zinc and magnesium produce very high strength.
Copper alloys are classified into electrical, machining, bearing, and high-strength grades according to additions of zinc, tin, aluminum, and beryllium.
Zinc controls the strength and machinability of brass.
Tin improves the wear and corrosion resistance of bronze.
Aluminum increases strength and seawater corrosion resistance.
Beryllium produces high strength and spring properties through precipitation hardening.
Magnesium alloys provide the lowest density and excellent die-casting performance, but corrosion and elevated-temperature strength require careful review.
Titanium alloys provide high specific strength and excellent corrosion resistance, while aluminum and vanadium additions control phase structure and strength.
Nickel alloys achieve high-temperature strength and extreme corrosion resistance through additions of chromium, molybdenum, niobium, and tungsten.
Zinc alloys achieve good die-casting performance and dimensional stability through additions of aluminum and magnesium.
Therefore, non-ferrous metal selection should consider:
Density
Strength
Elastic modulus
Corrosion resistance
Thermal conductivity
Electrical conductivity
Wear resistance
Castability
Formability
Weldability
Heat-treatment condition
Surface treatment
Galvanic corrosion
Food and environmental regulations
Cost and availability
Selecting a non-ferrous metal is not merely a process of replacing steel. It is a design process that uses the unique properties of each material according to the function and operating environment of the component.