Chapter 9

Significance of Alloys

1. Alloying can create metals that are able to work in an environment or application that the base metal could not 2. There are more than 25,000 different types of steel alloys 3. There are more than 200 standard copper alloys Here is an example: Molecular structure of steel - an iron alloy.

Features of Superalloys

1. Can survive without degradation in temperatures as great as 1200°C (2200°F) for reasonable periods of time when used in a non-load-bearing structure 2. Can be used at 1000°C (1800°F) under load 3. Influenced by oxidation, hot corrosion, and thermal fatigue 4. The surfaces are often coated with other materials when used in abrasive applications, such as turbine blades

Unified Numbering System (UNS) for classifying steel

1. Developed by the American iron and Steel Institute and Society of Automotive Engineers 2. Uses a four or five digit number to identify the principle alloying ingredient and percentage of carbon in hundredths of a percent.

Non Ferrous Metal - ALUMINUM

1. Easy to Form 2. Resistant to corrosion 3. Lightweight 4. a good electrical conductor

4 major classifications of metals

1. Ferrous Metals 2. Non Ferrous Metals 3. High temperature superalloys 4. Refractory metals

Types of Cast Iron:

1. Gray iron (most popular type) 2. Pig iron (refined wrought iron) 3. White cast iron (very hard, used for parts used in extreme wear conditions) 4. Malleable iron (made by heating white cast iron to a specific temperature and then slowly cooling using a process called annealing 5. Ductile cast iron (Nodular iron)

Cast iron is:

1. Hard 2. High carbon content 3. High corrosion resistance 4. Natural lubricity 5. Easy to crack 6. Engine blocks

Steel is:

1. Hard. 2. Tough 3. Alloy of Iron and CXarbon

Mechanical properties of metals to consider when designing a product:

1. Hardness The resistance of a material to penetration 2. Tensile strength The ability of a material to resist being pulled apart 3. Fatigue Breakage due to a stress being continually removed and reapplied 4. Ductility The ability of material to be formed plastically without breaking 5. Plasticity The ability of material to change shape or size as a result of force being applied

Mechanical properties can be determined using standardized testing procedures:

1. Hardness -- Rockwell test or Brinell test 2. Tensile strength 3. mpact test - Charpy 4. Ductility 5. Toughness 6. Elasticity - Young's Modulus of Elasticity 7. Fatigue

Non Ferrous Metals - COPPER

1. Nonferrous Metals have no iron content 2. Copper and copper alloys are classified by the Unified Numbering System (Copper Development Association) and by purity Example: C10100 through C15500 copper has 99.5% or greater purity 3. Pure or nearly pure copper is soft, easy to form, and resistant to corrosion

Major Types of Steel:

1. Stainless steel (alloy of nickel and chromium), corrosion resistant 2. Carbon steel (carbon is the principle alloying element) 3. Low carbon steel (.05% to .30% carbon) 4. Medium carbon steel (.30% to .60% carbon) 5. High carbon tool steel (.60% to 1.50% carbon) 6. Tool steel (high-carbon steel) very hard

List 3 alloys of pure metal:

1. Steel 2. Brass 3. Bronze

Nature of industrial Stock

1. The product of primary manufacturing firms 2. Secondary manufacturing companies transform an industrial stock into useful consumer products 3. Most metals are purchased by the pound in standard shapes and sizes 4. Ferrous and nonferrous metals can also be obtained in other forms for processing such as powder, billets (bricks), flakes, or pellets

Wrought Iron is:

1. Tough 2. Ductile 3. Nearly pure iron 4. Easy to bend without heating 5. Ornamental ironwork

What are some applications of refractory metals?

1. welding tips 2. turbine blades 3. crucibles

who has a system to ID steel according to properties

American Iron and Steel Institute (AISI) and the Society of Automotive Engineers (SAE)

Why is alloying so important? Hmmmmmmm

An alloy can have the best attributes of the base metal and its physical properties, but is significantly enhanced by the addition of another element

Mechanical properties of metals

CAN be controlled or changed.

T/F: there is only one way to classify nonferrous metals and super alloys.

FALSE: There are SEVERAL methods used for classifying non ferrous and superalloys - which are techniques to identify steel types.

How many types of metals are there?

FOUR

There are a variety of systems in use today to identify and describe what 4 types of metals

Ferrous, nonferrous, superalloys, and refractory metals.

Refractory metals can withstand ______ heat

HIGH!

Superalloys are used in:

High Stress Applications

Refractory Metals

High temp metals such as niobium (Melting point is 2477 degrees celsius) and tungsten (Melting point is 3410 degrees celsius)

Most commonly used metals in the world today are:

Iron and Steel

List 2 types of ferrous metals:

Iron and steel

What do you if no markings or IDs are available?

Machinists and toolmakers grind the stock and examine the pattern and color of the sparks

Non Ferrous Metals are:

Metals that do not contain iron (aluminum, copper, lead, magnesium, nickle and zinc)

High temperature superalloys are

Normally iron based, nickel based, or cobalt based but may also contain chromium, titanium, aluminum or tungsten

Sizing stock

Steel plate or sheet is sized in thickness by a gage. Small Gage = THICKER stock

T/F: Although the physical properties are fixed, manufacturers can change the mechanical properties of most of the common metals

TRUE

T/F: Physical properties are not the same s the mechanical properties of metals.

TRUE

T/F: All materials have their own unique physical properties that distinguish one form another.

TRUE! A heavy metal, such as LEAD, is denser and has a tighter molecular structure than a lightweight material, such as aluminum.

T/F: Physical Properties distinguish one metal from another

TRUE: Examples: 1. Specific Heat: the amount of energy needed to raise one gram of material one degree Celsius 2. Thermal Conductivity: the ability of a substance to conduct heat. 3. Thermal Expansion: metals expand in response to heating and contracting on cooling

T/F: Steel is also classified by the way it is shaped (which gives it a distinctive finish)

TRUE: hot rolled has a scaly bluish color while cold rolled steel is shinny silver gray

T/F: The Physical properties of metals are used to classify them for specific manufacturing processes and product applications.

True.

Methods for ID Steel:

Unified Numbering System (UNS) indicates the quantity of carbon in hundredths of a percent

An ALLOY consists of:

a blend of two or more materials

Ferrous Metals are:

metals containing iron (steel is an alloy with iron as the base metal)

Refractory Metals include:

niobium, tungsten, molybdenum

ID Aluminium 2000 - 8000 Series

see image

ID Aluminum 1000 series

see image

List some Pure Metals

see image

Examples of Physical Properties

tensile strength, hardness and toughness

Physical property of metals can NOT be changed by a secondary manufacturer, therefore selecting :

the correct metal or alloy for a specific application is essential