Knowing the world of metals

and alloys means create solutions!

Metals and Its Alloys, their crystalline structure and

properties

By: M. Sc. Arnaldo Valdés Carrazana.WEB: https://acarrazana.coursesites.comEmail: acarrazana@salcc.edu.lc

OBJECTIVES• To analyze the most common alloys

used in engineering.

• To explain the influence of the crystalline structure and the grains in the final properties.

• To explain the main tests to obtain the mechanical properties.

• To familiarize with the classification of steels and its nomenclature according to AISI , SAE and European codes.

Pure Metals in the Periodic Table.

Materials Classification ChartPure Metals and

their Alloys CompositePolymeric Ceramic

Ferrous = (Base Iron)

• Pure Iron (Fe).

• Steels (Fe+C where C<1.7%)

• Cast Iron (Fe+C where C1.7%)

Nonferrous = (No Iron)

• Aluminum (Al) and its alloys (Silumin and Duralumin)

• Copper (Cu) and its alloys (Brasses and Bronzes)

• Nickel (Ni) and its alloys

• Precious metals (Au, Ag)

• Refractory metals (Nb, Mo, Ta, Ti).

• Thermoplastics

• Thermoset• Elastomers

• Glasses• Ceramic

s• Graphit

e• Diamon

d

• Reinforced plastics• Metal-matrix

composites• Ceramic-matrix

composites• Sandwich structures• Concrete

Metal: any of several solid mineral elements (such as iron, gold, silver, copper, etc.) that are malleable under heat or pressure and can conduct heat and electricity; element yielding positively charged ions in watery solutions of its salts.

Ferrous, is an adjective used to indicate the presence of iron. The word is derived from the Latin word ferrum (iron). Ferrous metals include steel, cast iron (Alloys Fe+C) and alloys of iron with other metals (such as stainless steel).

Non-ferrous is used to indicate metals other than iron and alloys that do not contain an appreciable amount of iron.

Alloy: The mix of two or more substances where at least one of them is a metal. For example Steels, Cast Iron, Silumin, Duralumin, Brass, Bronze, etc. Pure metals have not practical use in industrial applications due the low properties.

Brief Comparison

Ferrous Alloys (Base Fe)

• Magnetic (Because the Iron presence)

• Heavy (Density=7.85g/cm3)• Superficial Rust• Color Dark Brown

Non Ferrous Alloys (Base Al, Cu, etc.)

• Non Magnetic• Light • No Superficial Rust• Color (Gray, Silver, Yellow,

Orange)

Identification of metals and Alloys

Internal structure.

• Macrostructure: Naked eye or low magnification.• Microstructure: Optical Microscope (400-1500x)• Substructure: Electron Microscope (Scanning or

transmission) up to 1000000x• Crystal Structure: X-ray Diffraction• Electron structure: Spectroscope• Nuclear structure: Nuclear Magnetic Resonance (NMR)

a. Simple cube (SC)

b. Body Centered cube (BCC)

c. Face Centered Cube (FCC)

Crystalline microstructure in Pure Metals.

Crystalline structure is a result of the an arrangement of atoms during the solidification process.

Note: In some metals and its alloys this structure changes not only during the cooling process, and the final structure depends on the cooling rate determining its final properties. For example Fe and Steels.

Stages during the Solidification in metals.

1. Nucleation: It begins at foreign particles in melt.

2. Crystal growth: Crystals begin to grow from each.

3. Grain Formation: Interface develops.

4. Polycrystalline structure: Grain growth is limited by another grain, creating a boundary between them

Crystalline Structure of Pure Metals.

All atoms are held in place by electromagnetic forces. If an external force is applied the crystalline network can be broken if such force is higher than the Yield Strength (YS).

A low strength level only cause a temporal deformation called (elastic deformation).

A higher strength lever (higher than the Yield Strength of the material will cause permanent deformation called (plastic deformation) by breaking the bunds between atoms.

Crystalline Structure of Alloys.

The crystalline structure of an alloy will be reinforced by the presence of foreign atoms. This explains why in Industrial applications Pure metals are not used. In other words a particular alloys (Example Steel) is stronger than the pure metal (Fe).

Metal Properties

Mechanical Properties

TechnologicalProperties

Physical Properties

• Traction• Compression • Bending

Impact (Toughness)

Hardness

• Brinell (HB)• Rockwell

(HR)• Vickers (HV)

• Weldability• Machinability• Malleability• Corrosion Resistance

• Melting Point (Tm)• Density ()• Thermal conductivity ()• Specific heat (C)• Electrical resistivity ()• Magnetic permeability ()

Technological Properties:

• Weldability: The ability of an alloy to be welded well, using simple procedures.

• Machinability: The ability to make parts using machining cutting tools.

• Malleability: The ability of the metal to keep the shape after the deformation without cracking in the edges.

Are those properties in relation with the Manufacturing Processes or Service. The valuation is usually qualitative (Good, Regular, Bad). Quantitative Methods also can be used.

Eng. Symbol

Parameter name ISO Symbols

USA Symbols

p Proportional Limit

e Elastic Limit Re

y Lower Yield Strength Rp Ys

y0.2 Conventional Yield Strength Rp0.2 Ys0.2

t=u Ultimate Tensile Strength Rs UTS or TS

δ Relative Strain (Elongation) A δ

Poisson’s ratio (Estriction) Z

Strength-Strain Diagram obtained from the Traction Test.

YS0.2

(MPa)

δ (%)0.2 %

TS

Al, Cu and its Alloys

Coupon Test

=d0-d1

d0

δ L1-l0

l0

= ll0

=

Fracture

σ=E*δ

δ (%)

(MPa)

YSpe

TS

elastic plastic

STEELSNecking

Uniform Elongation

1MPa=10.19 kg/m2=145.04 psi

l0

l1

d0

d1

Metal or Alloy TS (MPa) Ys (MPa) δ- (%)

Steels 1725 205 65-2Iron 185-285 40-200 60-3Aluminum 90 35 45Aluminum Alloys 90-600 35-550 45-4Copper 220 70 45Copper Alloys 140-1310 76-1100 65-3Nickel 320 58 30Nickel Alloys 345-1450 105-1200 60-5Titanium 275-690 140-550 30-17Titanium Alloys 415-1450 344-1380 25-7Molybdenum Alloys 90-2340 80-2070 40-30Magnesium 160-195 90-105 15-3Magnesium Alloys 240-380 130-305 21-5

Typical values of Ultimate Tensile Strength, Yield Strength and Elongation.

Note: (MPa “Mega Pascal” is the unit of strength in International System and psi “pound per square inches” in Imperial System)

How to choose the filler metal for welding?

δ (%)

(MPa)

YS

TSBM

TSFM

TSFM ≥ TSBM

The strength of the weld (Filler Metal) during fusion welding, should be equal or higher than the metal to weld on (Base Metal)

This cannot be possible only during Brazing or Soldering since the nature of both FM and BM are not the same.

Pendulum Impact

U or V notch10mm

10m

m

55mm

Coupon Test for Impact.

IndenterD

Di

Coupon Test

Applied Force

Hardness Test.

a. Brinell Method.

b. Rockwell Method.

Note: Hardness is important for elements of machines, not for structures or other.

Physical Properties of several Metals and Alloys.

Metal or Alloy Density ()(kg/m3)

Thermal conductivity ()

W/(m·K) (t=20⁰C)

Melting point (Tm)(⁰C)

Aluminum 2712 204 659

Aluminum alloys 7700 - 8700 120 - 180 462-671

Brass - casting 8400 - 8700 990 - 1025

Red Brass 8746 159 1027

Yellow Brass 8470 115 930

Bronze - lead 7700 - 8700 850 - 1000

Copper 8930 385 1083

Gold 19320 318 1063

Pure iron 6800 - 7800 72 1530

Cast Iron 7850Gray (1370), Malleable

1360,White (1370)

Wrought Iron 7750 58 1450

Lead 11340 35.3 327

Nickel 8800 89 1453

Silver 10490 406 961

Solder 50/50 Pb Sn 8885

Non alloyed and low alloy steel 7850 53.6 1480

Stainless Steel 7480 - 8000 12.11 - 45.0 1430-1500

Tin 7280 63 232

Zinc 7135 115 419

Procedure for Calculation of Weight.

𝑊=𝑉 ∗𝛾𝑉=𝐴∗𝐿

V: Volume (cm3)

: Specific Weight (g/(cm3)

A: Cross Sectional Area (cm2)

Examples.Example 1: In a workshop there are 4 cranes (0.5Tn, 1.3Tn, 4Tn and 7Tn). Which one cannot be use for lifting a steel slab with dimensions (4000x1000x40mm)?  Solution: Calculating the weight of a steel slab: Weigh (W)=Volume (V)*(Density) W=(4M*1M*0.04M)*7850Kg/M3=1256kg=1.3Tn Consequently cranes for (0.5 and 1.3) shouldn’t be used to lift the slab. Example 2: Find out the weight of a similar slab made out of Aluminum.  W=(4M*1M*0.04M)*2712Kg/M3=433kg=0.4Tn This can be lift with the (0.5Tn crane). Example 3: How many times steel weigh more than Aluminum? Solution: 7850/2712=2.89=2.9 times.

Steels Classification ChartSteels = Fe + C where (C ≤ 2.14%)

Non Alloy Steels(Plain Carbon) Steels

Alloy Steel

Low CarbonC < 0.3%

Medium Carbon0.3% ≤ C < 0.5%

High Carbon0.5% ≤ C < 1%

Low Alloy ∑AE < 5%

Medium Alloy5%≤ ∑AE <10%

High Alloy∑AE ≥ 10%

Cr-Mo

Cr-Mo-V

Ni (cryogenic)

Cr-Ni (Stainless Steel Cr12%)

Mn (Hadfield)

Ni (Maraging)

Several types Si, Si-Mn, etc

Mild Steel: Non Alloy and low carbon steel with C from 0.16 to 0.29%, which is used in 85% of all steel applications in the world.

Ultra High Carbon1.0% ≤ C ≤ 1.7%

Application of Alloys

• Structures: Bridges, Buildings, Decks, Cranes, Pipelines, Vessels, etc.

• Elements of Machines: Pistons, Bearings, Shaft, Levers, etc. Parts that move.

• Devices: Appliances, Power tools, Furniture, and other.

• Tools: Pliers, Screwdrivers, etc. • Other: Pipes, Tubes, Fittings, Cables, etc.

Type of alloy Grade Criteria of use Type of supply Examples

Steels

LCNA(C<0.3%)

Good Weldability Good Malleability Good Machinability

Bars, Flats, Sheet Metal, Beams, Pipes

Structures; Elements of machines were

hardness is not an issue. Devices

MCNA0.3≤C<0.5%

For manufacturing Elements of machine. For Machining + Heat Treatment to change

superficial hardness. Regular Weldability (Not for manufacturing

welding)

Bars Elements of Machines where hardness is important.

HCNAC≤0.5%

To withstand deformation and wearing. Bad Weldability (Not for welding at all) Bars Tools

Springs

LCLAC<0.3%; ∑AE<5%

Similar to LCNA but more Tensile strength, Resistant to marine corrosion.

Bars, Flats, Sheet Metal, Beams, Pipes

Structures.

LCMAC<0.3%

5%≤∑AE<10%

Thermal Resistance and Thermal stability (Cr, Mo) Pipes Pipelines

Low temperature Applications Pipes, plates Pipelines Special equipment.

MCLA and

MCMA

Similar to MCNA but more hardness after heat treatment. Bars Tools

Elements of machines

LCHA (Stainless) Rust Free Luxury Antibacterial

Pipes, Flats, Sheet metal

Food containers Chemical industry equipment. Medical equipment

LCHA (Hadfield) Elements that get harder with working impacts Casting Tracks and rolls of caterpillars

and similar equipment. Railroad.

Elongation (%)

% C0 0.5 1

500

1000

15

30

0

Strength (MPa)

TS

YS

Influence of the carbon content in the Mechanical Properties of the steel.

Influence of the Alloy Elements in Hardness and Impact) in Steels.

Examples of classification of steels:

1. An steel with the following chemical composition: C=0.15%; P<0.002%, S<0.001%

Will be classified as Low Carbon Non Alloy (LCNA) Steel .

Notes:

• Sulphur (S) and Phosphor (P) always are impurities in steels (They are not Alloy Elements).

• Since C0.15%, such steel is also called Mild Steel.• Low Carbon Steels have GOOD WELDABILITY and

MALEABILITY.

Example 2:

2. An steel with the following chemical composition: C=0.15%; Mn=1%, Si=2.0% P<0.002%, S<0.001%

It Will be classified as:Low Carbon and Low Alloy (LCLA) Steel with 3.0 % of Alloy Elements.

LCLA Steels usually have GOOD or ACEPTABLE Weldability.

Example 3:

3. An steel with the following chemical composition:

C=0.035%; Cr=18% and Ni=8%

Will be classified as:

Extra Low Carbon High Alloy (LCHA) Steel with (18 + 8)=26% of Alloy Elements. This is a typical Stainless Steel.

Identification of American Steels

According to the American Iron and Steel Institute (AISI) and the Society of Automotive Engineering (SAE) Steels are identified as follows:

• A Four Digits code for Non Alloy, Low Alloy and Medium Alloy Steels. In this case the last two digits represents the carbon content in percentage while the first two digits the subgroup of steels according the alloy system and application.

• A three digit code for High Alloy Steels (AISI) or five digits (SAE) where the last two of the five represents the carbon content.

Notes:

1. In the following tables XX represents the carbon content in percentage.

2. American steels are used worldwide.3. Some countries like Japan use same nomenclature.4. The most of European countries follow a totally different

nomenclature for example (Germany, Italy, Russia, France and England).

Carbon Steels

10XX Plain carbon, Mn 1.00% max11XX Resulfurized free machining12XX Resulfurized - Rephosphorized free machining15XX Plain carbon, Mn 1.00-1.65%

Manganese Steel 13XX Mn 1.75%

Nickel Steels23XX Ni 3.50%25XX Ni 5.00%

Nickel-Chromium Steels

31XX Ni 1.25%, Cr .65-.80%32XX Ni 1.75%, Cr 1.07%33XX Ni 3.50%, Cr 1.50-1.57%34XX Ni 3.00%, Cr .77%

Molybdenum Steels40XX Mo .20-.25%44XX Mo .40-.52%

Chromium-Molybdenum Steels 41XX Cr .50-.95%, Mo .12-.30%

Nickel-Chromium-Molybdenum Steels

43XX Ni 1.82%, Cr .50-.80%, Mo .25%47XX Ni 1.05%, Cr .45%, Mo .20-.35%

Nickel-Molybdenum Steels

46XX Ni .85-1.82%, Mo .20-.25%48XX Ni 3.50%, Mo .25%

Identification of NA, LA and MA Steels.

Chromium steels

50XX Cr .27-.65%51XX Cr .80-1.05%

50XXX Cr .50%, C 1.00% min51XXX Cr 1.02%, C 1.00% min52XXX Cr 1.45%, C 1.00% min

Chromium-vanadium steels 61XX Cr .60-.95%, V .10-.15%

Tungsten-chromium steels 72XX W 1.75%, Cr .75%

Nickel-chromium-

molybdenum steels

81XX Ni .30%, Cr .40%, Mo .12%86XX Ni .55%, Cr .50%, Mo .20%87XX Ni .55%, Cr .50%, Mo .25%88XX Ni .55%, Cr .50%, Mo .35%

Silicon-manganese

steels92XX Si 1.40-2.00%, Mn .65-.85%, Cr 0-.65%

Nickel-chromium-

molybdenum steels

93XX Ni 3.25%, Cr 1.20%, Mo .12%94XX Ni .45%, Cr .40%, Mo .12%97XX Ni .55%, Cr .20%, Mo .20%98XX Ni 1.00%, Cr .80%, Mo .25%

Stainless Steels SAE AISIChromium–Manganese–Nickel Steels 302xx 2YY

Chromium–Nickel Steels 303xx 3YY Chromium Steels 514xx 4YY Chromium Steels 515xx 5YY

Identification of High Alloy Steels.

In the most of the European countries to identify high alloy steels the chemical element is specified and after the amount except when is 1% for example:

• 08Cr18Ni10T is a steel containing: 0.08%C, 18%Cr, 10%Ni and 1%Ti• 06Cr12Ni25 is a steel containing: 0.06%C, 12%Cr, 25%Ni

Gray Malleable

• Whiteheart• Blackheart• Perlitics

Spheroidal graphite (SG).

• Ordinary• ADI

WhiteVermicular or Compact

Non alloyed

FerriticFerritic - Perlitics

Perlitic High Temperature

Abrasive Wear with

Impact

Anti-friction

(Whites)

• Cr• Cr-Ni• Cr-Mo

(Gray)

NiSi

(Gray)

• Ni• Si• Al

Whites

•Cr

(Gray)

NiSi

Corrosion

Classification and application of Cast Irons.Cast Iron (C 1.7%)

Alloyed

Note: Cast Iron is obtain out of Casting process (in a mold) and it is use for parts that have to withstand vibrations and compression loads.

Applications of Copper Alloys.

Brasses (Cu+Zn)

• Yellow (Cu-Zn)

• Leaded (Cu-Zn-Pb)

• Tin (Cu-Zn-Sn-Pb)

Bronzes (Cu+Sn).

• Phosphor (Cu-Sn-P)

• Lead Phosphor (Cu-Sn-Pb-P)

• Aluminum (Cu-Al-Ni-Fe-Si-Sn)

• Silicon (Cu-Si-Sn)

Copper Alloys.

Note: Cooper alloys, are mainly used in pipes, tubes, valves, fittings, antennas and in some cases friction bearings.

Generic name Major components UNS designation number

Copper (Technically Pure) >= 99.3% Cu C10100…C15999

High-copper alloys > 96% Cu but <99.3% Cu C16000…C19999

Brasses

Yellow Brasses Cu-Zn C21000…C28999

Leaded Brasses Cu-Zn-Pb C30000…C39999

Tin Brasses Cu-Zn-Sn-Pb C40000…C49999

Bronzes

Phosphor Bronzes Cu-Sn-P C50000…C52999

Lead Phosphor Bronzes Cu-Sn-Pb-P C53000…C54999

Copper-Phosphorous alloys Cu-P, Cu-P-Ag C55000…C55299

Copper-Silver-Zinc Alloys Cu-Ag-Zn C55300…C60799

Aluminum Bronzes Cu-Al-Ni-Fe-Si-Sn C60800…C64699

Silicon Bronzes and Silicon Brasses Cu-Si-Sn C64700…C66199

Other copper-zinc alloys Cu-Zn-… C66200…C69999

Copper-Nickels (Copper-Nickel-Iron Alloys)Spinodal Bronzes

Cu-Ni-FeCu-Ni-Sn C70000…C73499

Nickel Silvers Cu-Ni-Zn C73500…C79999

Classification of copper alloys is determined by the Unified Numbering System (UNS),developed by the American Society for Testing and Materials (ASTM), Society of Automotive Engineers (SAE) and the Copper Development Association (CDA). The designation system uses five-digit numbers preceded by the prefix letter C. The numbers from C10000 through C79999 define the wrought copper alloys.

Identification of Copper Alloys.

Generic name Major components UNS designation number

Coppers >= 99.3% Cu C80000…C81399

High-Copper Alloys > 96% Cu but<99.3% Cu C81400…C83299

BrassesRed Brasses and Leaded Red Brasses

Cu-Sn-ZnCu-Sn-Zn-Pb C83300…C84999

Yellow Brasses Cu-Zn C85000…C85999

Bronzes

Manganese Bronzes and Leaded Manganese Bronzes Cu-Zn-Mn-Fe-Pb C86000…C86999

Silicon Bronzes and Silicon Brasses Cu-Zn-Si C87000…C87999

Copper-BismuthCopper-Bismuth-Selenium alloys

Cu-BiCu-Bi-Se C88000…C89999

Tin Bronzes and Leaded Tin Bronzes

Cu-Sn-ZnCu-Sn-Zn-Pb C90000…C94500

Nickel-Tin Bronzes Cu-Ni-Sn-Zn-Pb C94600…C94999

Aluminum Bronzes Cu-Al-Ni-Fe C95000…C95999

Copper-Nickels (Copper-Nickel-Iron Alloys)Spinodal Bronzes

Cu-Ni-FeCu-Ni-Sn C96000…C96999

Nickel Silvers Cu-Ni-Zn-Pb-Sn C97000…C97999

Copper-Lead Alloys Cu-Pb C98000…C98999

Special alloys Cu-… C99000…C99999

The numbers from C80000 through C99999 define the cast copper alloys.

Conclusions.

• In industry Pure metals has not use, due the low properties. Alloys offer better properties due the inclusion of foreign atoms in the crystalline structure.

• The chemical composition have influence in the Mechanical, Technological and Physical properties.

• The most common alloys in our environment will be (Steels, Brasses, Bronzes and Cast Iron).

Internet References

• Crystalline Structure. • NTD Resource Center• Wikipedia Encyclopedia• How Stuffworks• AISI / SAE Steel Identification Number • Stainless Steels International Standards.