Forging new generations of engineers Heat Treating Metals Principles of EngineeringTM Lesson 6.3 – Production Processes Forging new generations of engineers Project Lead The Way, Inc. Copyright 2007

Heat Treating Metals

Heat Treating Heat Treatment - Is The Heating And Cooling Of Metals In Their Solid States For The Purpose Of Changing Their Properties.

Principle Kinds Of Heat Treatment Hardening Tempering Annealing Normalizing Case-hardening Flame Hardening Induction Hardening

Heat-treatment Processes All Heat-treatment Processes Involve Heating And Cooling Metals According To A Time-temperature Cycle Listed Below Heating The Metal To A Predetermined Temperature. Holding The Metal At This Elevated Temperature For A Certain Period Of Time. Cooling The Metal At A Certain Rate Of Time.

Heat Treating Furnace Electric Or Gas

Furnace Temperature Control Heat Treating Metals Principles of EngineeringTM Lesson 6.3 – Production Processes Furnace Temperature Control Celsius Degrees On Inside Scale Fahrenheit Degrees On Outside Project Lead The Way, Inc. Copyright 2007

Temperature Indicating Materials That Melt At Exact Temperatures Pellets Crayons Liquid

Effects Of Temperature On Hardness Of Steel Higher Rockwell Number The Harder The Steel

Effects Of Carbon Content On Hardening Of Steel Low-carbon .05-.30 No Heat Treating Medium-carbon .30-.60 Some Hardening High-carbon .60-1.5 Can Be Made Extremely Hard

Steps For Hardening Check Carbon Content Of Steel It Must Be Above .30 Percent To Harden Heat Furnace To The Upper Critical Temperature 1400 To 1700 Degrees (F) Check Heat Treating And Carbon Graph To Determine This Value. Allow Steel Time To Completely Heat Through Out. Cool Or Quench Heated Steel As Rapidly As Possible In Water, Brine Or Oil. Steel Should Now Be Very Hard, Brittle And Ready To Temper.

Graph Of Temperature Ranges And Carbon Content For Heat Treating Plain Carbon Steel Line ac3 shows upper critical temperature Line ac1 shows lower critical temperature Line ac2 shows point at which steel looses its magnetism

Tempering Steps For Tempering Tempering Is A Heat Treating Process That Reduces Some Of The Hardness In Steel To Gain Toughness And Strength Steps For Tempering Steel Must First Be Hardened Reheat Steel To The Tempering Temperature Determined By Chart In Next Slide. Quench Or Cool Steel Quickly After It Reaches Its Tempering Temperature

Tempering Temperature Chart

Annealing Steps For Annealing Annealing Is A Heat Treatment Process To Soften Steel & To Remove Internal Stress Steps For Annealing Heat Steel Up To The Upper Critical Temperature (Ac3 Chart) Hold Steel At This Temperature And Heat Thoroughly Through Out. This Is Called Soaking. Cool Steel Very Slowly By Removing It From The Furnace And Packing It In Sand Until It Reaches Room Temperature.

Case-Hardening Steps To Case-harden Case-hardening Is A Surface Only Hardening Process. This Combines Hardness With Strength & Toughness Steps To Case-harden Usually Done With Lower Carbon Steels. Pack Steel In Powered Carbon Carburize By Heating In A Furnace At The Required Temperature For 8 To 12 Hours. Now Harden Steel With The Normal Hardening Method.

Heat Treating Review Why is heat treatment done? How is carbon content in steel related to hardening? List steps to follow for hardening. What is tempering why is it done? List the steps to follow for tempering. What is annealing and why is it done? List the steps to follow for annealing. What is case-hardening why is it done? List the steps for case-hardening. List 3 ways temperature is determined.