Ch 4 Classifying Metals

Brass is an alloy of copper and

zinc

Rare earth metals are easily separated from their ores into individual elements.

False

The basic ingredient of nonferrous metals is iron.

False

Identify four applications of rare earth metals.

Super magnets Electric motors Wind turbines Crystal laser rods

Carbon steels are classified by their percentage of carbon in ______________________________, or hundredths of one percent.

points

Metals that are rare, less chemically reactive, and highly valued are ____ metals.

precious

Some composite metals consist of two parts: a matrix and a(n) ______________________________.

reinforcing agent

Silver combined with a small amount of copper produces ______________________________.

sterling silver

Bronze is an alloy of copper and ____.

tin

Most ____ alloys are capable of continuous operation at temperatures of about 800°F (427°C).

titanium

Beryllium is very toxic.

true

List three useful qualities of aluminum alloys.

1. Stronger, pound-for-pound, than steel 2. Very light 3. Easy to shape and form

List three precautions that should be observed when handling metals.

1. Wear eye protection 2. Wear gloves 3. Never drop wet/moist metal into molten metal

Define and explain a cermet.

A cermet is a composite where a metal matrix is reinforced using ceramic materials. The material is usually made from carbide ceramics which are bound with metals such as cobalt and nickel.

What are composites? What are their desirable characteristics?

A family of materials that consist of two or more distinct materials that are physically combined. They are known for corrosion resistance, stiffness, and strength-to-weight ratio

What is an alloy?

A mixture of two or more metals.

What is a base metal?

A pure metallic element used as the principal alloying agent in many different metals.

What is a honeycomb structure? What purpose does it serve?

A type of sandwich structure where the core resembles the hexagonal structure of a honeycomb. The composite structures are bonded together using adhesives or by brazing or resistance welding. It is used to give metals greater strength and rigidity while reducing their weight.

The ____ systems of identifying steels uses a four-number code.

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

The two main classes of aluminum alloys are wrought alloys and ______________________________ alloys.

Cast

Which of the following is the alloying element that keeps stainless steel from rusting?

Chromium

____ improves the red hardness and wear resistance of alloy steel.

Cobalt

____ steel is produced when hot-rolled steel is pickled and passed through a dilute acid to remove the oxide coating.

Cold-finished

List the five groups into which metals designed for industrial use are usually classified.

Ferrous metals Nonferrous metals Precious metals High-temperature metals Rare earth metals

Briefly explain how cold-finished steel is produced.

First, the metal is pickled or passed through a dilute acid to remove the oxide coating. It is then rolled into a final shape and size while it is cold.

______________________________ metals are sometimes called superalloys and include niobium, molybdenum, tantalum, and tungsten.

High-temperature

______________________________ steel is characterized by the black oxide coating that forms during the rolling process.

Hot-rolled

How do ferrous and nonferrous metals differ?

Nonferrous metals do not contain iron as a basic ingredient, whereas ferrous metals contain iron as the basic ingredient.

____ steels are tough, dense steels with high carbon or alloy content that are used to make tools that must hold a cutting edge.

Tool

Copper is a base metal used as an alloying element that conducts electricity and develops patina when exposed to the atmosphere

True

High-speed steels resist wear and retain strength at high temperatures.

True

Metallurgists develop metals with special properties that will do a specific job better or more economically.

True

Molybdenum is added as an alloying element when the steel must remain tough at high temperatures.

True

Silver, gold, and platinum are examples of precious metals

True

____ melts at a higher temperature than any other known metal.

Tungsten

____ iron is extremely hard and used primarily in applications requiring wear and abrasion resistance.

White cast

____ iron is an iron alloy with most of the carbon removed from its composition.

Wrought

A(n) ______________________________ is a semifinished steel bar with a relatively square cross section measuring more than 36 in 2.

bloom

Rolling processes reduce molten steel or ingots into semifinished ____ shapes.

bloom, billet, or slab

Aluminum, magnesium, and titanium are all ferrous metals.

false

Basic group of metals classified as stainless steel include austenitic, martensitic, and ____.

ferritic

The strength of aluminum can be increased by ____.

forging, rolling, extruding, hammering (this is characteristic of all wrought alloys)

The thickness of sheet metal is specified by a

gage number

Sheet steel coated with zinc is said to be

galvanized

The ____ part of composite materials provides the form and binds the materials together.

matrix

Metals that do not have iron as their basic ingredient are ____ metals.

nonferrous

When added in the proper amount, tungsten makes steel self-hardening.

true