ITP 260 MIDTERM I Study Guide (Module 1-3)

Alloy Steel

-The mechanical and chemical properties of plain carbon steel can be improved (strengthened) by dissolving atoms of other metal element in solid solution of steel. -This solid solution of steel is called alloy steel. Two common alloy steels are: tools steel and stainless steel.

Atom

-The smallest particle of an element -All materials composed of atoms

Cast Iron

2-4% Carbon in Iron -Iron can no longer digest all the carbon -Too brittle for rolling and forming -Only good for casting -Low tensile strength, high compression strength -Bed/foundation, machinery, water hydrants, pulley

Mechanical Deformations

A material deforms in response to the forces applied to it. Elastic Deformation -At low forces the material deforms elastically Plastic Deformation -At higher forces the material becomes permanently deformed

Manufacturing Systems

A network of manufacturing processes involving changes in a product's: Geometry Chemical Properties Appearance of Material Examples Include Drilling Milling Turning Grinding Welding Heat Treatment Painting

Processing Operations

Application of mechanical, thermal, and chemical energy to alter a material shape, mechanical properties, or appearance. Casting Processes -Starting materials heated into liquid state and poured into cast/mold -Casting for metals and modeling for plastics Particulate Processing -Starting materials are powders of metals or ceramics -Powders are squeezed in die cavity and heated to bond Metal Forming Processes -Starting stock is shaped by application of forces Material Removal Processes -Excess material removed from stock material using processes such as turning, drilling, milling, and grinding. Joining (Assembly) Processes -Permanent Joining of materials through processes such as welding and mechanical fastening. Surface Processing -Coating material in powders, coating, or painting Composite Material Fabrication

Metals conduct electricity because their valence electrons:

Are free to move

The chemical property (reactivity) of materials are affected by_____

Arrangement of valence electrons

Atomic Slip vs. Atomic Cleavage

Atomic Slip -Tendency to pull atoms apart when subjected to loads -If bonds are weaker or have natural presence of defects (voids or dislocation) then crystals have atomic slip Atomic Cleavage -Tendency to pull atoms apart when subjected to loads -If bonds are very strong between atoms (like in ceramics) then crystals are cleaved.

Atomic Structure on Material Properties

Atomic properties and interactions determine the ultimate use characteristics of industrial materials. Electron arrangement surrounding nucleus affects... -Electrical properties -Magnetic properties -Thermal properties -Optical properties Atomic bonding and imperfection affect... Mechanical properties of material.

Hardness of metals is affected by:

Crystalline structure defects

Production Systems

Total company's involvement in the manufacturing process including: -Equipment -Facility -Product/System Design -Materials and Supplies -Workers -Machines -Information System -Management

Production Management Approaches

Traditional Approach: Batch and Queue Production More Efficient Approach Flow Line Production / One-Piece Flow

A material could be extremely hard but exhibits poor toughness when subject to a rapidly applied force.

True

Metals lose electrons when combined with other elements.

True

Vacancy (void) defects in metals' crystalline structure are desirable for ease of deformation.

True

Within the elastic range, materials maintains original shape and size when external load is removed .

True

Tool Steel

Type of alloy steel Yield Strength: 195000PSI -Chromium, Molybdenum, Tungsten, Vanadium -Used as shaping and cutting tool material -High hardness, high wear resistance, good heat resistance, good strength, and high resistance to softening. -Used in cutting tools (HSS), stamping dies, hot forging dies, extrusions dies, plastic forming molds, powder pressing dies.

Atoms Combining

Maximum Stability -Outer shell of electrons must be filled to be stable -Some atoms naturally stable (Neon and Helium) -Atoms bond to create stable conditions

Materials have tendency to combine with each other because their atoms have tendency to reach to ________ in their outer shell.

Maximum stability and 8 electrons in outer shell in (in most cases)

Mechanical Stresses

Measure of force applied to a component relative to the cross- sectional area over which the force is applied. o = F/ A Tensile Stress Pulls a member apart Compressive Stress Crush, collapse, or buckle a member Shear Stress Cleave or slice a member Torsional Stress Twist a member Bending Stress Deflect a member

Material Selection and Mechanical Properties

Mechanical properties are considered when selecting materials that are subject to force because... Ease of Processing -Highly dependent on mechanical properties -Hardness and Ductility Resistance of Material -Applied load during use of product -Highly depends on mechanical properties -Yield strength, hardness, toughness, fatigue resistance BCC crystals stronger than FCC crystals due to more atomic slip.

Primary Bonds

Metalic Bond -Atoms held together by matrix of electrons -Metals for electron clouds -Cloud has negative charge and holds positive ions together -Weak bond Covalent Bond -Sharing electrons in outer shell -Often found in polymeric materials -Sharing complete outer shell -Good plasticity and moderate strength Ionic Bonding -Bonding in which ions that have lost or gained an electron bond with one another. -Materials such as sodium chloride and many ceramics -Very strong and very brittle

Toughness (Impact strength)

Used to measure a material's ability to withstand the shock of a rapidly applied load. It is expressed in foot-pound.

Metals, NonMetals, Metalloids, and Semiconductors

Metals -Groups 1-12 -Conduct electricity and heat well -Magnetic Field (Cobalt, Nickel, Iron) -Noble Metals (Silver, Gold, Platinum) -Commonly have 1, 2, or 3 valence electrons -Lose electrons when combining with other elements NonMetals -Groups 13-17 -Do not conduct electricity or heat very well -Commonly have 5, 6, or 7 valence electrons -Gain electrons when combined with other elements Metalloids -Elements found along stair-step line distinguishing metals from non-metals -Have properties of metals and non-metals -Always have 4 valence electrons -Gain/lose electrons when combined with other elements -Semiconductors Semiconductors -Can carry electric charge under special conditions -Often used in computers and calculators

Metal Characteristics

Metals can be characterized by... 1. Nature of bonds between atoms 2. Make up of crystals Metallic Bond -Metals are solids composed of atoms held together by matrix of electrons (sea of electrons) -Good conductors or electricity -Current flow requires flow of electrons Metallic Characteristics -Malleable -Opacity -Ability to strengthen

Mechanical Microstructure

Microstructure properties of materials have significant impact on mechanical properties Microstructure Properties -Grain size -Crystal structure -Inclusions (impurities) Strength of ceramics dependent on porosity and grain size Large Grain Size -Softer material becomes Smaller Grain Size -Harder the material becomes

Molecule, Alloy, Compound (Ceramics)

Molecule -Smallest part of a compound that still retains the properties of that compound -Formed by joining two or more atoms -H2O Alloy -Metal combined with one or more other metallic elements -Normally solid -Brass (Copper and Zinc) Compound -Substance contenting two or more elements chemically combined in fixed proportions -Ceramics (Al2O3, NaCl)

Three metals that can produce magnetic field are:

Nickel, Iron, Cobalt

Organic vs Inorganic Material

Organic Material -Contains carbon and hydrogen (hydrocarbons) -Derived from living things like plants and animals -Petroleum and plastics Inorganic Material -Not derived form living things -Sand, rocks, water, metals

Recycling aluminum is preferable to extracting it from mines because of:

high cost of extraction of raw aluminum low electricity cost of melting recycled aluminum

In steel grade AISI 5160, what do the first two digits (51) stand for?

indicates it is a Manganese/ Chromium steel alloy

Electrical conduction in metals occurs by migration of____

valence electrons

With regard to AISI 5160 steel, what do the second two digits stand for?

~0.60% carbon

Tensile Strength

Resistance of a material to forces trying to pull it apart. -Maximum stress on the stress-strain curve. -Point where material begins to neck. See slide:_ -Referred to as Ultimate Tensile Strength ( <Jut) -Not used much in design of products, but is an important consideration in shaping (manufacturing) of parts.

Hot Rolled Steel (HRS)

Steel shaping process -Red hot steel runs through rolls, grains are squashed down, but immediately grow back into smaller grain sizes (recrystallization). -Deformation and recrystallization take place simultaneously. As a result metal will not exhibit strain hardening. -HRS remains soft: No change in hardness or ductility -The smaller the grains, the tougher the metal. -HRS has a thin black scale due to exposure to air at red hot state. -Inexpensive, used in building frames (I-beam)

Industrial Revolutions

Stone Age: 10,000 years ago Bronze Age: 2,000 years ago Iron Age: 2,000 years ago Earliest Machine Tool: Lathe (1400 AD) Steam Engine: (1650-1750) First Industrial Revolution (End of 18th Century) -Development of Steam Engine Power -Growth of Production and Mechanization -Lathe was first very important machining tool Second Industrial Revolution (19th Century) -Mass production and Electricity -Henry Ford's assembly line (1913) -Steel Age and Modern Technology of Iron -Blast Furnace -Eiffel Tower Third Industrial Revolution (20th Century) -Solid state electronics and computers -Development of computerized machinery -Flexible Automation -Huge variety of new materials such as metals, polymers, ceramics, and composites.

Crystalline Structures in Metals

Structures in Metals -Crystalline structure -Stronger than amorphous structure (disordered) -Crystalline structure arranged in repeating structure shown in Unit Cell -Junctions in crystalline structure are called grains Properties affected by... -Type of unit cell -Grain size -Strength of bonds between atoms

Elastic Limit

The maximum stress that a material can withstand without taking a permanent deformation

A common Titanium alloy used in orthopedic implants is made of:

Titanium, Aluminum, Vanadium

Cold Work Effect

-Because of these defects (voids) a metal part can be deformed (shaped) by cold working (cold forging, extrusion, bending). -After cold working the metal becomes harder because less empty sites (voids) are available, making atomic slip more difficult.

Three Facets of Manufacturing

-Consider Product Requirements (Shape/Function/Quality) -Use Right Material -Use Right Process Challenge: Finding the best combination of facets that meets business needs

Effect of Defects

-Defect is a crystal imperfection characterized by region of severe atomic misfit or voids during solidification where atoms are not properly surrounded by neighbor atoms. -It would be extremely difficult to deform metals in manufacturing processes without defects. -Defect-less crystal structures are the strongest because the bonds between atoms are perfect.

Periodic Table

-Elemental dictionary -Shows family groupings -Shows valence electrons

Grains

-Group of crystals that have same orientation. -Smallest units of crystal structure in a metal -Can be controlled by heat treatment. Small Grains -Harder to deform due to more obstacles to deformation force (or atomic slip). -Made by rapid solidification of materials. Large Grains -Easier to deform due to less obstacles to deformation force.

Manufacturing Capabilities and Process Selection Consideration

-Involved in planning for manufacturing -Are technological processing capabilities available? -What are the product's physical size and weight? -What is production and plant capacity (production quantity that can be made in a given time)?

Noble Gasses

-Last vertical grouping -Very stable with full valence electron rings -Do not react with other elements -Argon and Helium used as shield for protecting molten metal during welding

Shop Floor Operations

-Material Handling -Processes -Packaging -Inspection and Testing -Storing

Chemical Properties

-Measure how materials interact with other materials in environment (gases, liquids, and solids) -Valence electrons determine chemical properties -Oxidation -Corrosion -Degradation -Toxicity -Flammability

Yield Strength / Elastic Limit

-Point on stress-strain curve where plastic deformation begins -Stress below yield strength allows materials to maintain shape when unloaded -Very important for product design

Cold-Rolled Steel (CRS)

-Production process starts with pickling cold HRS in an acidic solution to remove the black oxide scale. -Steel then rolled into various shape Features: a. No recrystallization. It is called cold-rolled because it is formed at below recrystallization temperature. b. Steel becomes harder due to atomic slip during cold rolling process, which results in higher strength than HRS. c. Has a smoother and shinier finish, no scales. d. Close size tolerance, no expansion/shrinkage issue e. Steel becomes brittle if extensive rolling is applied. To reduce the brittleness it must be heat treated (annealed). Heat treatment recrystallizes the rolled steel, results in recovery of its ductility property. f. Applications: machinery parts g. CRS is about 30% more expensive than HRS. However, parts can be made in smaller thickness or cross section compared to HRS because of its higher strength (hardness).

Element

-Simplest type of substance consisting of one type of atom

Mechanical Properties

-Stress -Strain -Elastic/Plastic Deformation -Formability (Ductility) -Durability (Hardness) -Toughness (Impact Strength) -Fatgue

Argon does not react with other materials because it has:

8 electrons in its outer shell

Stress-Strain Diagram

A graphic representation of the relationship between unit stress values and the corresponding unit strains for a specific material.

Material, Process, & Product Design

All related through their interactions to determine the right process and materials to be used. Product Design: Functions and Shape -Light weight -Durable -Insulate -Shape -Accurate -Surface Finish Materials Properties -Density -Strength -Toughness -Recyclability Manufacturing Processes -Casting -Forging -Machining Business Operations Factors: -Demand -Cost -Environmental Impact -Safety -Government Regulations -Sustainability

Units Cells

BCC -Good strength -Brittle -High melting point (Iron, chromium, tungsten, molybdenum) FCC -Moderate Strength -Ductile -Easily formed (Aluminum, copper, gold, nickel, silver, platinum) HCP -Brittle (Cobalt, titanium, magnesium, zinc) Allotropics Have two different forms of unit cell depending on temperature

Physical Properties

Characteristics that can be observed without changing the identity of the substance Density -Measure of mass/volume -Important material property in manufacturing -Lower density materials critical for reducing weight Melting Point -Directly effects include heating material to reach melting point for casting and molding -Indirect effects include determining what temperature a metal must be heater for heat treatment or hot forging Thermal Conductivity -Measure of material's ability to conduct heat -Challenges include heat insulation and heat conduction Thermal Expansion -Rate at which a material elongates when heated -Adverse effects include thermal expansions and shrinkage in welding parts -Useful effects include thermocouples and shrink fit assembly -Occurs by migration of valence electrons -Ceramics and Polymers are good insulators Electrical Conductivity -Amount of electric charge that passes through a unit cube of the material per unit of time -Occurs by migration of valence electrons -Ceramics and Polymers are good insulators Ferromagnetism -The ability of a material to be attracted by magnetic field Magnetically Hard materials: -Make good permanent magnets. Materials include low carbon steel, iron alloys containing aluminum, nickel and cobalt, and samarium -Example: Computer hard drive Magnetically Soft Materials: -Most steels are ferromagnetic (non-permanent magnet) -Example: Electric motor core

The strength of steel can be improved by:

Cold Rolling and Hot Forging

Plain Carbon Steels

Contains 0.06%-1% Carbon Melting Point 2795 F Yield Strength: 51,000PSI for 1040 steel Low Carbon Steel (Mild Steel) -0.06%-0.3% Carbon -Cannot be heat treated -Inexpensive, soft, easily machined or forged -Non-Critical applications -Bolts, nuts, screws, sheet metal Medium Carbon Steel -0.3%-0.8% Carbon -Can be heat treated -Harder and stronger than mild steel -Engine parts, gears, crankshaft, springs, bolts High Carbon Steel -0.8%-1% carbon -Very hard material -Cutting tools, drill bits, taps, blades

Formability (Ductility) vs Percent Elongation

Ductility -Measure of a material's ability to be stretched or drawn before it breaks. -Reported as percent elongation or reduction in the cross section area. Percent Elongation -Ratio of increase in length incurred in the sample up to the point of fracture relative to the initial length of the sample. -The higher the percent elongation, the more ductile and formable the material is. -Percent Elongation = (change of length / original length) %

The electrical property of materials depends on arrangement of ________ surrounding the nucleus.

Electrons

Nickel and platinum have ________ unit cell structure while chromium and tungsten have _____ structure.

FCC, BCC

After rolling a steel plate for several times, heat treatment is applied to increase the hardness of the metal.

False

Aluminum has higher "electrical conductivity" than copper.

False

Ceramics are substances made of one type of elements listed in periodic table of elements.

False

Crystalline polymers have lower melting point than amorphous polymers.

False

Decision for selecting a right cutting tool usually is not relevant to the hardness of the workpiece material.

False

In ionic bond, the valence electrons are shared between atoms.

False

In plastic deformation, atomic slip does not cause permanent change of shape.

False

Larger crystal grains are harder to deform due to less obstacles to deformation force.

False

Metals and water are considered as organic materials.

False

Most metals with FCC crystals are stronger than metals with BCC crystals.

False

Subjecting a metallic part to mechanical load can cleave its crystal structure.

False

Titanium is an excellent choice for marine environment especially when coupled with other metals.

False

The effect of carbon on properties of steel...

Increasing carbon content increases hardness and strength and improves hardenability by heat treatment. But carbon also increases brittleness and reduces ductility. American Iron and Steel Institute (AISI) has devised a 4-digit ID: XXXX First two digits: represent alloy content Last two digits: represent carbon content in 0.01 % Examples: In 1045: 10 represents plain carbon steel 45 means 0.45% carbon In 4140: 41 represents Chromium\Molybdenum steel 40 means 0.40% carbon

Some atoms can attain stable condition by:

Losing or gaining electrons

Product/Material Life Cycle

Product is... -Material produced -Manufactured -Used by consumer -Disposed of by consumer -Refurbished for reuse/ recycled for material production

Production Machines and Tooling

Production Machines: -Presses for stamping operations -Forge hammers for forging -Rolling mills for rolling sheet metal -Welding machines for welding -Milling machines for removing material Tools in Manufacturing: -Cutting tools for material removal -Mold/Die for casting, forging, stamping -Workholding/Fixture devises

Mechanical Property Tests

Tensile Test -Measures the strength or resistance of a material to pulling forces. Impact Test -Measures a material's ability to withstand shock loading. Hardness Test -Measures the resistance of a material to permanent indentation

Elasticity

The ability of a material to return to original size and shape after the external forces causing the change has been removed

Parts made of high carbon steel are stronger than parts made of medium carbon steel because of:

their higher carbon content their hardness might have been improved by heat treatment

What is manufacturing?

The process of converting raw materials into finished products by application of: Mechanical Energy Thermal Energy Chemical Energy

Valence Electrons and Material Interaction

Valence Electrons are most involved in bonding between atoms Valence electrons indicate the tendency to combined and form new substances. Many chemical and mechanical properties of solids are based on number of valence electrons.

Carbon steel is _______ times stiffer than Aluminum .

three

Durability (Hardness)

a) Hardness is resistance to scratch or indentation. b) Hardness is resistance to localized deformation. Hardness is often equated with wear resistance and durability. It is a measure of abrasion resistance.

Cold working ______ yield strength, and ________ ductility.

decreases, decreases

The mechanical properties of materials influence __________ of the materials significantly.

ease of processing

At what rate aluminum expands compared to steel at elevated temperatures?

twice compared to steel

What property of brass or bronze makes them excellent material for for M-T-M wear systems (bearings)?

low coefficient of friction

Steel becomes _______due to ______ during cold rolling process.

strain hardened, atomic slip

Specific strength is a measure that is based on:

strength to density ratio