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• Define metallurgy.
• Understand the primary cause-and-effect relationships encountered
in metallurgy.
• Explain why the study of metallurgy can be a valuable asset in jobs
other than direct production.
• Explain why every step in a production process is needed to
produce a good, working part.
Learning Objectives
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• Describe how metallurgical knowledge can be used to solve
industrial problems.
• Explain how research scientists, metallurgical engineers, operations
technicians, and equipment operators all contribute to make
process and product improvements.
Learning Objectives
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• Materials are metals and nonmetals (most are metals).
• Metals are ferrous or nonferrous.
• Ferrous metals’ major component is iron.
• All other metals are nonferrous.
• More than 80 different ones
Classifying Materials
Goodheart-Willcox Publisher
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• Ferrous metals have wide variety of applications.
• Depends on alloying elements added to iron
• Depends on processing used
• Steel contains lower levels of carbon (up to 2%).
• Most common type is mild steel.
• Low carbon
• Lower strength
Ferrous Metals
Goodheart-Willcox Publisher
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• Other commercial grades of steels
• Stainless steels
• Specialty steels
• Cast irons contain roughly 2%–4% carbon.
• Different alloying elements added for desired properties
Ferrous Metals (cont.)
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• Desirable properties in metal achieved
by selecting suitable composition and
processing it properly
• Processes performed create
microscopic structures in metal, called
microstructures.
Composition and Processes Determine
Microstructure and Properties
Goodheart-Willcox Publisher
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• Microstructure determines properties.
• Different processes on same alloy can produce different
microstructures/properties.
Composition and Processes Determine
Microstructure and Properties (cont.)
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• Common processes affecting microstructures and properties
• Forming
• Heating to different temperatures
• Rapid or slow cooling from elevated temperatures
Processes
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• Different processes result in different internal structures.
• Small changes in processes can change metal properties.
• Understanding of these relationships helps to adjust procedures
when something unexpected occurs.
Adjusting Processes
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• Knowledge of metallurgy helps solve metal-related problems.
• Knowledge of metallurgy helps find workable solutions.
• Following slides show examples of how metallurgical knowledge
helps.
• Design better metal parts
• Select best metal for applications
• Troubleshoot manufacturing problems
Practical Examples of Metallurgy
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• Steel sheet formed into desired shape (blades) by stamping and
bending processes.
• Properties obtained by heat treatment.
• One day, reject rate for blades jumped.
• Metallurgical problem
• Mill producing steel sheet had changed processing slightly.
• Additional stresses formed in metal while rolling into sheet.
• When heat-treated, each piece relieved stresses by warping.
Warped Lawnmower Blades
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• Metallurgical solution
• Before forming, heat as-received sheet to elevated temperature for
two hours.
• Relieves internal stresses caused by rolling
Solution to Warped Lawnmower Blades
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• Metallurgical problem
• Bend cultivator steel control arm linkage for easier movement.
• Metallurgical solution
• Heated end to be bent with blowtorch until red hot
• Used hammer and anvil to bend end to better fit
• Reheated linkage to bright yellow and plunged into bucket of water
• Filed off scale on heated end and reheated one last time
Steel Heat Treatment on the Farm
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• Metallurgical problem
• Axle shaft of large tractor must support bending and twisting forces.
• Engineers need to increase strength.
• Conditions to keep costs down
• No increase in diameter
• No alloy change
Tractor Axle Shaft
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• Metallurgical solution
• Current part made by heat-treating axle
shaft
• Careful testing showed higher strength
achievable by adjusting heat treatment.
• Required closer control of heating and
cooling processes
Strengthening a Tractor Axle Shaft
Warner Consulting, Inc.
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• Metallurgical problem
• Cutting tool losing its edge
• Cutting tool must be harder than
workpiece being cut.
• Frictional heat can soften hardened
steel tools.
• Soft tools do not cut well and must
be replaced.
Cutting Tool
PERO studio/Shutterstock.com
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• Metallurgical solution
• Changing to different steel type reduces problem.
• Some steel types withstand higher temperatures.
• Tools last longer.
• Machinists maintain higher production rate.
Improving Cutting Tool Durability
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• Metallurgical problem
• Sometimes strength is not only
requirement.
• Metallurgical solution
• High-strength aluminum alloy is strong
enough.
• Made from heat-treatable alloy
• Aluminum can be polished to look good.
Hood Lifters for Show Car
Ringbrothers
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• Manufacturer’s problem
• Entire shipment of lock washers
rejected after over 50%
fractured when installed
• Salesperson explained
customer’s viewpoint.
Fractured Compression Lock Washers
Jay Warner; Goodheart-Willcox Publisher
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• Product engineer and production supervisor explained process for
making lock washers.
• Stamped from sheet steel
• Twisted slightly to lock against nut when installed
• Finally, electroplated
• Plant metallurgist determined failures were brittle fractures.
• Likely caused by hydrogen embrittlement
Compression Lock Washers
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• Metallurgical solution
• Electroplating drives hydrogen into the steel.
• Baking drives hydrogen out of the steel.
• Check of production records spotted missed process step of baking.
• Corrective actions
• Explain importance of baking process to drive out hydrogen.
• Develop ways to assure step is not missed again.
Compression Lock Washers (cont.)
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• Radiators extract heat from hot fluids flowing through tubes.
• Heat flows from tubes, to metal fins, to surrounding air.
• Aluminum or copper foil used for metal fins
• The thin foil is called fin stock.
Cooling Fins for Automobile Radiators
Sunti Wongyai/Shutterstock.com; Goodheart-Willcox Publisher
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• Dialysis uses blood coolers to control blood temperature while blood
is removed from patient.
• Fin stock for blood coolers is similar to that used in automotive
industry.
• Manufacturer of fin stock for automobile radiators expands business
by producing fin stock for blood coolers.
Cooling Fins for Blood Coolers
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• Problem
• Order rushed out without checking all specifications
• Order rejected for surface imperfections (gouges and tears)
• Cause: difference in performance requirements
• No scratches, gouges, or perforations acceptable for blood cooler fin
stock
• Technician who made order not aware of different specifications
Different Specifications for Cooling Fins
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• Artist’s concept
• Large, physically simple, reflective object showing surroundings (land
and sky)
• Effect similar to liquid mercury
• What material to accomplish concept?
• Ordinary steel rusts.
• Chrome-plated steel does not maintain shine at welds.
• Aluminum requires frequent repolishing.
Outdoor Sculpture: Chicago’s Cloud Gate
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• Metallurgical solution
• Used weldable stainless steel and
filler metal that matched in color
• Used arc and laser welding
• Welds polished and ground, leaving
no marks on surface
Outdoor Sculpture: Chicago’s Cloud Gate
(cont.)
Jay Warner
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• Everyone associated with metal manufacturing operations can
benefit from a knowledge of metallurgy.
• People directly involved in manufacturing need a great deal of
information.
• General technicians, maintenance people, and troubleshooters can
recognize problems that occur.
• Those who do not make metal products use metals to do their work.
Metals Are Everywhere
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• Metallurgy is improving, with new innovations and breakthroughs all
the time.
• Example: changing how oil is spread on a metal sheet
• May reduce number of rejected parts
• May allow increase in speed of stamping and forming
• May result in reduction of production cost
Advancing Metallurgy
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• Increased use of computer control and reporting
• Understanding the connections between composition, processes,
microstructure, and properties will continue to be important.
Advancing Metallurgy (cont.)
Goodheart-Willcox Publisher
