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Tool Steels (part 2)
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The
tool steels are categorized as shown in Figure 1. Steels are categorized by quench
and application. |
by David Pye | January 20, 2012 | Comments (0)
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Tool Steels (part 1)
| I will be presenting a series of articles on tool steels, tool-steel categorization,
tool-steel heat treatments and heat treating of specific tool steels. |
by David Pye | January 9, 2012 | Comments (0)
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Cryogenic Treatment (part 4)
| This
is the final part on the subject of cryogenic treatments (known also as deep
freeze or cold treatment). |
by David Pye | December 16, 2011 | Comments (0)
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Cryogenic Treatment (part 3)
| The question that could be asked right now is how do we
cold treat, or cryogenically treat, steel for the potential decomposition of
retained austenite? |
by David Pye | December 9, 2011 | Comments (0)
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Cryogenic Treatment (part 2)
| The
continuation of cryogenic treatments is to ask why do we cryogenically treat
steels, and how do we identify those steels that will need to be cryogenically
treated? |
by David Pye | November 11, 2011 | Comments (0)
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Cryogenic Treatment (part 1)
| The
subject of cryogenic treatment has been around for many decades... |
by David Pye | October 27, 2011 | Comments (0)
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Normalizing
| Much
has been written about the procedure of normalizing. However, it still puzzles
me as how little industrial engineers know about the subject and what creates
the steel metallurgy and mechanical properties associated with the process. |
by David Pye | October 17, 2011 | Comments (1)
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Aluminum and its Heat Treatment (part 2)
| The
thermal-strengthening processes for the three heat-treatment aluminum alloys
are solutionize and precipitation-hardening treatments. |
by David Pye | September 2, 2011 | Comments (0)
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Aluminum and its Heat Treatment (part 1)
Hardness Testing
| Hardness
testing is what will determine the success of metallurgical processing. It is a
procedure that is so often taken for granted and done without too much thought. |
by David Pye | August 12, 2011 | Comments (0)
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Incoming Material Inspection
Gas Carburizing
| Many years ago, F.E. Harris of MIT was tasked with improving productivity during the early part of World War II. His particular task was to investigate the process of gas carburizing.
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by David Pye | July 1, 2011 | Comments (0)
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Process Control for Nitriding
| As is with any heat-treatment process, some sort of process control will be necessary in order to produce repeatable and consistent metallurgy and uniform mechanical properties.
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by David Pye | June 16, 2011 | Comments (0)
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Pre-Heat Treatment of Steels for Nitriding
| Steels to be nitrided require a pre-heat-treatment procedure prior to final nitriding.
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by David Pye | June 9, 2011 | Comments (0)
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Influence of Time and Temperature on Distortion of Carburized Steels
| When steel is raised in temperature and held at that constant temperature in which the austenite state is achieved in the steel, there is a strong influence on the grain size and, consequently, there will be the problem of distortion occurring.
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by David Pye | June 2, 2011 | Comments (0)
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Soft Spots on Nitride-Treated Components
| The subject of soft spots on nitride-treated components is often a very misunderstood subject.
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by David Pye | May 20, 2011 | Comments (0)
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Vacuum Degassing of Steel (part 2)
| As discussed last time, it can be seen that the procedure will clean up most of the steels’ impurities (certainly as far as gas is concerned). Sometimes sulfur is removed (or reduced) by the vacuum degas method.
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by David Pye | May 13, 2011 | Comments (0)
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Vacuum Degassing of Steel (part 1)
| Vacuum degassing is a procedure that is used to improve the internal cleanliness of steel after the initial melt has occurred.
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by David Pye | April 29, 2011 | Comments (0)
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Steelmaking (part 4)
| The electric-arc furnace is as its name implies – an electric arc.
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by David Pye | April 15, 2011 | Comments (0)
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Steelmaking (part 3)
Steelmaking (part 2)
| An early method of making steel was to use what is known as the open-hearth furnace.
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by David Pye | March 25, 2011 | Comments (0)
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Steelmaking
| We deal with steel on almost a daily basis. If we are not using steel in our travel (to work and home), it’s what we work with daily in the heat-treatment shop.
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by David Pye | March 18, 2011 | Comments (0)
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Hardness Testing, Surface Preparation
| The results of hardness testing are what will determine the success of the heat-treatment procedure and the materials’ response to that heat treatment.
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by David Pye | March 11, 2011 | Comments (0)
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Tempering and Brittle Phases (part 2)
Tempering and Brittle Phases (part 1)
| It has often been stated in many text books, lectures and metallurgical schools that one must temper as soon as the quenched steel is at “hand warmth” or at approximately 150˚F so that the risk of cracking of the steel is significantly reduced.
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by David Pye | February 18, 2011 | Comments (0)
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Safety in Heat Treatment (part 3)
| City gas is a generic name for the heating gas that is supplied to us via pipeline to the factory facility. Not all city gas is created equal. |
by David Pye | February 4, 2011 | Comments (0)
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Safety in Heat Treatment (part 2)
Safety in Heat Treatment
| The heat-treatment shop is the facility in a steel-processing or a manufacturing facility that relies on its own heat-treatment plant to service its components.
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by David Pye | January 21, 2011 | Comments (0)
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Atmosphere Furnace Burnout
| Once again we face the contentious issue of “burnout” on atmosphere furnaces.
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by David Pye | January 14, 2011 | Comments (0)
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Distortion During Nitriding
| Distortion during any heat-treatment procedure is a problem that will occur, but it is not necessarily the fault of the heat treater.
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by David Pye | January 7, 2011 | Comments (2)
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Effect of Time during the Carburizing Process
| As far back as 1943, F.E. Harris developed a formula for the calculation of time in relation to temperature for the depth of carbon penetration into steel during the carburizing process.
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by David Pye | December 17, 2010 | Comments (0)
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Carbon Diffusion into Steel During Carburizing Process
| The rate of diffusion of carbon into steel while in the austenite phase is concerned with carbon in solid solution in austenite.
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by David Pye | December 10, 2010 | Comments (0)
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Principles of Laser Surface Heat Treatment
| The principles of laser surface heat treatment are in essence the same principles of metallurgy that are applied to traditional steel thermal phase transformation.
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by David Pye | November 12, 2010 | Comments (5)
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Distortion of Induction Hardened Steels
| The subject of induction heat treatment is no more complex than the thermal transformation of, say, a tool steel or an alloy steel.
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by David Pye | October 22, 2010 | Comments (0)
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Tempering
| The purpose of tempering is to create a new structure from the as-quenched martensitic structure of a particular steel.
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by David Pye | October 15, 2010 | Comments (0)
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High-Temperature Carburizing
| Carburizing has been traditionally accomplished at temperatures in the 1700˚F range.
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by David Pye | October 1, 2010 | Comments (0)
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Surface Soft Spots
| The problem of soft spots on surface-treated work such as nitriding, ferritic nitrocarburizing, carbonitriding and carburizing is a very common occurrence in heat treatment today.
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by David Pye | September 17, 2010 | Comments (0)
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Carbide Precipitation in Tool Steels
| The hardness of the high-alloy tool steels in the as-quenched condition does not usually exhibit the full hardness that can be obtained with that steel.
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by David Pye | September 3, 2010 | Comments (0)
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Internal Oxidation when Carburizing
| What does it mean when we hear the term “internal oxidation” when carburizing?
|
by David Pye | August 20, 2010 | Comments (0)
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How to deal with Retained Austenite after Carburizing/Harden (Part 2)
| It can be concluded that the remaining austenite is soft even though it is saturated with carbon.
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by David Pye | August 13, 2010 | Comments (0)
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More on Heat-Treatment Training
| Heat-treatment training and the enhancement of knowledge for a heat treater should be an ongoing process.
|
by David Pye | August 6, 2010 | Comments (0)
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How to Deal with Retained Austenite after Carburizing/Harden
| When steel is carburized in the austenite condition, the austenite is a very stable metallurgical phase.
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by David Pye | July 30, 2010 | Comments (0)
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Core Hardness for Nitriding
| The secret of nitriding is not so much the nitriding itself or the forming of the stable nitride case, but the prior core treatment is what will give success to the nitriding process.
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by David Pye | July 16, 2010 | Comments (0)
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Spark Testing: Seeing the Spark
| What effect do the alloying elements have on the resulting spark of the sample? |
by David Pye | July 2, 2010 | Comments (0)
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Spark Testing
| The art of spark testing seems to be forgotten.
|
by David Pye | June 25, 2010 | Comments (0)
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Heat Treatment and Metallurgical Training
| Once again we write about training. I believe that training is fundamental to a new hire/new associate (unless he has already been trained).
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by David Pye | June 18, 2010 | Comments (0)
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What is Hardenability?
Advantages, Disadvantages of Induction Heat Treatment
| Much has been written, discussed and debated about the values of the process of induction heat treatment.
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by David Pye | May 14, 2010 | Comments (0)
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Annealing of High-Speed and Other High-Alloyed Tool Steels
| The annealing of high-speed steels has been somewhat of a mystery as to how it should be accomplished.
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by David Pye | May 7, 2010 | Comments (0)
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Carbide-Forming Elements
| Carbide-forming elements are an essential requirement for the steel to have the ability to harden and produce satisfactory hardness results as well as the required mechanical properties on either through- or case-hardening steel.
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by David Pye | April 30, 2010 | Comments (0)
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Training for Heat-Treatment Associates
Factors That Influence Microcracking in Carburized-Steel Cases
| What factors will influence microcracking in a carburized case?
|
by David Pye | April 2, 2010 | Comments (0)
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Surface Oxidation and its Effects on Brazed Joint Quality (Part 2)
| The formed oxide surface is extremely hard to wet with the braze filler metal at the liquid temperature of the filler metal.
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by David Pye | March 26, 2010 | Comments (1)
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Surface Oxidation and its Effects on Brazed Joint Quality
| The success of brazing and the joint integrity will be dependent on the quality of prior surface preparation before brazing is completed.
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by David Pye | March 19, 2010 | Comments (1)
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Surface Oxidation: What Is It and What Causes It?
| Surface oxidation is caused by oxygen attacking the surface of steel at temperatures ranging from room temperature up to whatever process temperatures are chosen unless the steel surface is protected.
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by David Pye | March 12, 2010 | Comments (0)
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High-Carbon, High-Chromium Tool-Steel Heat Treatment
| The tool steels that generally fall into this category are the D-series and A-series tool steels.
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by David Pye | March 5, 2010 | Comments (0)
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Carbide Composition During Carburizing (Part 2)
| When designing an optimized carburizing operation, considerations should be given to the following...
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by David Pye | February 26, 2010 | Comments (0)
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Carbide Composition During Carburizing
| During some carburizing operations, carbides might form.
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by David Pye | February 19, 2010 | Comments (1)
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Solutionize, Quench and Precipitation of Aluminum Alloys (Part 2)
Solutionize, Quench and Precipitation of Aluminum Alloys (Part 1)
| There are only three groups of aluminum alloys that will respond to strengthening by thermal means.
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by David Pye | February 5, 2010 | Comments (0)
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Nitriding Core Support
| The nitriding process has been misunderstood over the years.
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by David Pye | January 29, 2010 | Comments (0)
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Normalizing
| How can one ensure that the steel for carburizing will respond in the same manner each time that it is processed?
|
by David Pye | October 22, 2009 | Comments (2)
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Decarburization
| The term decarburization simply means the loss of surface carbon from the steels being treated.
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by David Pye | October 16, 2009 | Comments (0)
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What is Intergranular Oxidation?
| Intergranular oxidation (IGO) is a phenomenon that occurs as a result of gas carburizing due to the process-gas decomposition.
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by David Pye | October 9, 2009 | Comments (0)
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Corrosion
| Corrosion is an everyday and natural occurrence on metals such as steel, aluminum, copper and other metals.
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by David Pye | August 27, 2009 | Comments (0)
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A-Series Tool Steel
| A-series tool steels are relatively easy to heat treat due to the alloy content, with significant amounts of...
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by David Pye | August 13, 2009 | Comments (0)
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Why is it Necessary to Select the Correct Austenitizing and Quench-Medium Temperature After Carburizing?
| The entire process – carburize, austenitize and quench – must be based on accurate process control of both carbon potential and temperature.
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by David Pye | August 6, 2009 | Comments (0)
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How Does Bainite Form in Alloys Steels?
| Bainite is a metallurgical structure/phase, which is caused by cooling from an appropriate austenitizing temperature, to a preselected temperature above the Ms line of the Time-Temperature-Transformation (TTT) diagram.
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by David Pye | July 23, 2009 | Comments (0)
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New or Used? – That is the Question (Part 2)
| The question is frequently asked, “Do we buy new or do we only buy used?” There are many pros and cons to this age-old query. It simply is a question that can only be answered by the individual who is considering purchasing the proposed equipment.
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by David Pye | July 16, 2009 | Comments (0)
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New or Used? – That is the Question (Part 1)
| The question is frequently asked, “Do we buy new or do we only buy used?” There are many pros and cons to this age-old query.
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by David Pye | July 9, 2009 | Comments (0)
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Tool Steel Failures and Causes
| There are many possible causes of tool-steel failures in their operating environment.
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by David Pye | June 18, 2009 | Comments (0)
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Heat-Treatment Troubleshooting
| There are many aspects to the troubleshooting of heat-treatment problems.
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by David Pye | June 11, 2009 | Comments (0)
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Distortion: Who Holds the Key?
| Distortion plagues both engineer and heat treater alike, for no one can heat treat metal – steel in particular – without incurring distortion.
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by David Pye | June 4, 2009 | Comments (0)
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Adventures in Surface Treatments
| The study of surface treatments has been, and always will be, in the developmental state.
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by David Pye | May 29, 2009 | Comments (0)
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What Does the Future Hold for Heat Treatment? (Part 2)
| We are now becoming very “green conscious” in terms of gaseous exhaust emissions.
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by David Pye | May 15, 2009 | Comments (0)
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What Does the Future Hold for Heat Treatment? (Part 1)
| In 1991, I wrote a paper for the heat-treatment and surface-engineering conference, which was held in Amsterdam, the Netherlands.
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by David Pye | April 24, 2009 | Comments (0)
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Aluminum Heat Treatment
| There are only three groups of wrought aluminum alloys that can be successfully thermally strengthened using heat-treatment procedures.
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by David Pye | March 16, 2009 | Comments (0)
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Quenching
| The subject of quenching remains (to a large extent) a mystery to many product and process engineers.
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by David Pye | March 9, 2009 | Comments (0)
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What Causes Grind Burns on Carburized Gear Teeth?
| Gear-tooth grinding is a very contentious subject to engineers, metallurgists and heat treaters alike. It is important to understand the root cause of grind cracks.
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by David Pye | March 2, 2009 | Comments (2)
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What Promotes Internal Oxidation While Gas Carburizing?
| When oxygen diffuses into the steel surface during the carburizing process, it is usually along the austenitic grain boundaries.
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by David Pye | February 9, 2009 | Comments (0)
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Nitriding and its Pre-Heat Treatment
| The pre-heat treatment of nitrideable steel is just as critical and important as the final heat-treatment procedure of nitriding.
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by David Pye | February 2, 2009 | Comments (0)
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The Effects of Retained Austenite on Carburized Steels
| Retained austenite is a renowned occurrence as a result of the carburizing procedure. The occurrence of retained austenite is a result of...
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by David Pye | January 26, 2009 | Comments (0)
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A Gas Nitriding Review (Continued)
| When the cycle has commenced, the development of the nitrided case begins with the nucleation of gamma-prime into small “islands” at the interface between the ammonia atmosphere (decomposing) and the component being nitrided.
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by David Pye | January 15, 2009 | Comments (7)
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A Gas Nitriding Review
| Many companies are gas nitriding, and the process is 100 years old from the patent date. So, the process is not a new process. It is, however one of the “youngest” processes.
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by David Pye | December 23, 2008 | Comments (0)
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Quench-Oil Maintenance Recommendations
| Once again the price of oil is fluctuating. This time, it is decreasing in price. We can rest assured that the price will inevitably increase once again. This means that quench-oil price will also increase.
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by David Pye | December 2, 2008 | Comments (0)
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Calculating Electrical Energy for a Furnace Modification
Why Would We Experience Below Surface Hardness on a Plasma-Nitrided Case Using AISI 4140 Steel?
| When nitriding a steel, it is advisable to have a core with a phase structure of tempered martensite. The tempered martensite will assist with the support of the formed case.
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by David Pye | October 29, 2008 | Comments (0)
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The Choice of Continuous DC or Pulsed DC for Nitriding
| Most plasma nitriding systems in North America have been developed on the basis of continuous DC plasma generation. There are, however, a small number of pulsed-DC plasma-generation systems. The question is often asked which system should I choose?
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by David Pye | October 20, 2008 | Comments (0)
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Maintenance of Quench Oil
Gas Nitriding – Control or No Control
More About Distortion
What is the difference between plasma carburizing and low-pressure carburizing? (Part 2)
Why should we use pulsed plasma nitriding as opposed to gas or salt-bath nitriding?
If we use the low-pressure carburizing technique, how do we quench and into what medium?
| After low-pressure carburizing, one can quench as normal into, say, hot oil (if, of course, the vacuum furnace has a built-in integral-quench chamber).
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by David Pye | August 12, 2008 | Comments (0)
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What is the difference between plasma carburizing and low-pressure carburizing?
What causes the white layer (compound layer) to form during the plasma-nitride process?
Available Methods for the Deposition of Thin-Film Hard Coatings
| What are the methods available for the deposition of a thin-film hard coating for such surface coatings as titanium nitride, titanium carbonitride and titanium aluminum nitride?
|
by David Pye | July 23, 2008 | Comments (0)
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Problems Nitriding AISI 4140 Steel Using Gas Nitriding
| Question: We nitride AISI 4140 steel (bar stock) using the gas nitriding process, and we are experiencing problems of the nitride case exfoliating (peeling off). What is causing this?
|
by David Pye | July 16, 2008 | Comments (2)
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A Discussion on Distortion
| Heat treatment is necessary in order to manipulate the mechanical strength and metallurgy of the steel. The manipulation of the steel’s physical characteristics is necessary for prior machining and for the successful performance of the finish-machined component.
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by David Pye | July 7, 2008 | Comments (0)
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What causes hardness variation from heat to heat?
| We heat treat a great deal of AISI 4140 for harden and temper. Our austenitize temperature is 1570˚F (855˚C) and temper at 450˚F (235˚C). We always check the “as-quenched” hardness, and more often than not, we have hardness variances from heat to heat. Why is this?
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by David Pye | June 30, 2008 | Comments (0)
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What is the cause of surface grain-boundary oxidation on an atmosphere-carburized component made from AISI 8620?
When was Martensite First Discovered?
| People have been aware of and worked iron for approximately 4,000 years. However, its usage only became recognized around 1200 BC. This is because it was extremely difficult to smelt, melt, cast or forge because of temperature required.
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by David Pye | May 21, 2008 | Comments (0)
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Why is an AISI 1050 steel part decarburized during heat treatment in an endothermic atmosphere?
| The composition of the furnace atmosphere created by an endothermic generator is as follows: CO ~ 20%, CO2 ~ 1.0%, Hydrogen ~ 40%, Nitrogen ~ 35% and 4% methane. |
by David Pye | April 1, 2008 | Comments (0)
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Why is Stress Relieving Necessary?
| The reason for the metallurgical heat-treatment process of stress relieving is primarily to remove residual, induced stresses from the steel. These stresses will occur as a result of rolling, forging, machining, welding, etc. |
by David Pye | February 14, 2008 | Comments (0)
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What Causes Distortion?
| Distortion is caused by stresses in a part that are relieved during thermal treatment. These stresses include induced machining stresses from variations in the machining procedure and stresses caused by non-metallic inclusions due to differential rates of expansion. |
by David Pye | January 31, 2008 | Comments (0)
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