Understanding the Jominy end quench test
The Jominy end quench test (ASTM A255 ) is an extremely simple and useful test that is applicable to many materials besides steel...
The mechanism of creep and its stages
In this column, I will discuss the mechanism of creep and its three stages.
Applications of metals at elevated temperatures involve several problems. It is...
Use of molten salt in heat treatment
At the turn of the 20th century, the use of molten salt as a heating and quenching medium for steels was developed in England....
Heat treatment of aluminum VI – Artificial aging
In the previous column, we described the fundamentals of natural aging. In natural aging, the solid solution obtained after quenching starts to form precipitates...
Understanding the effect of boron in steels
In this column, we will discuss the effect of boron additions to steel and its influence on properties.
Boron, B, is an element with an...
Using water as a quenchant
In this short column, we will discuss quenching with water. As a quenching medium, plain water approaches the maximum cooling rate attainable in a...
Heat treatment of aluminum – Part II
In my article last month, I discussed the alloying elements used in aluminum alloys. In this article, I will be discussing the solution heat...
Heat treatment of aluminum – Part I: Quenching basics
In previous articles, we discussed the role of alloying elements and discussed the solution heat treatment of aluminum. We showed that it is important...
Heat treatment of aluminum, part II: Water quenching
In the last article, we talked about the metallurgy behind quenching aluminum. Now we are going to discuss the available quenchants for aluminum.
Introduction
To achieve...
Heat treatment of aluminum, Part V
After quenching and any straightening, the supersaturated solid solution of aluminum wants to reach equilibrium. It does this through the process of precipitation hardening....
Classifying non-metallic inclusions in steels
In this column, we will discuss the different types of inclusions present in steels and discuss their physical metallurgy. As property requirements increase, and...
Heat treatment of aluminum Part VII – Hardness and conductivity
In the previous article, we discussed the artificial aging of aluminum. Once we have heat treated the parts, we need to verify the properties....
Troubleshooting induction hardening problems: Part 1
Induction hardening is a unique method used to harden steels. The process uses a power supply, RF generator, induction coil, and quenching mechanism (spray...
Carbon: Essential element or too much of a good thing
52100: Simple, yet it embraces carbon’s two-way benefit to steel
Determining Grossman H-value from cooling curve data
In the last article, I described how the Jominy end quench test could be used to predict hardness for a series of different round...
The heat treatment of aluminum – Introduction
Aluminum’s many desirable properties, such as high strength-to-weight ratio, good corrosion resistance, ease of processing, and low cost, make it a very widely used...
Heat treating is not for the faint of heart
Why heat-treating furnaces look the way they do, Part 2
Furnace Doors
No matter the configuration, single or multi-chamber vacuum, batch integral quench, continuous, or even pits — an item that all furnaces have in common...
Heat treatment of aluminum, quenching Part III
In the last article, we discussed quenching of aluminum, and the importance of rapid quenching to prevent the formation of precipitates at the grain...
Safety considerations when quenching with oil or salt
In this column, we will consider safety aspects of quenching with oil or molten salt.
Heat treating is a manufacturing process where the goal is...
Cooling rate after tempering
In this column, I will discuss the effect of cooling rate after tempering.
Introduction
During heat treatment of steel, the process is generally austenitize, quench, and...
Predicting hardness by the Grossman H-Value
In the last article, we described a method of calculating the Grossman H-Value . In the article before last, we described a method of...
Heat treatment of aluminum IV: Handling distortion
After quenching, depending on the quenchant used, distortion of parts can occur. This is particularly true for water-quenched parts. Parts must be straightened. This...
Calculating decarburization
In this column, I will be talking about decarburization of steel and how to calculate its depth.
Introduction
Decarburization of steel is the depletion of carbon...
Understanding the basics of spray quenching
Spray quenching involves the removal of heat by the impingement of a liquid quenchant on a hot metal surface. Examples include:
Fog quenching.
Quenching...
Stainless Steels
Kitchen sinks, refrigerator or oven doors, and tableware are what many people think of when they are asked what’s made from stainless steel (SS)....
Blistering of aluminum during heat treatment
In this column, we will discuss the blistering of aluminum during heat treatment, and methods to prevent its occurrence.
Introduction
High-temperature oxidation, or blistering, often occurs...
Intergranular corrosion of austenitic stainless steels
In this column, I will discuss the intergranular corrosion of austenitic stainless steels (3XX) and discuss the thermal processing causes.
Introduction
Austenitic stainless steels, such as...
Control of distortion in heat-treated aluminum
In this column, we will discuss controlling the distortion of aluminum heat-treated components.
The heat treatment of aluminum (solution heat treatment, quenching and aging) are...
Estimating required flow through quench tanks
In this month’s column, I will discuss a method of estimating the required flow for a quench tank.
Agitation has a significant effect on...
Thermal expansion of mineral oil quenchants
In this column, I will discuss the thermal expansion of oil. This information is primarily important for initial fills of a quench tank.
Introduction
Oil, when...
Intergranular oxidation in carburizing steels
Intergranular oxidation (IGO) in carburizing steels is detrimental to carburized gear performance. It reduces fatigue performance and can contribute to surface spalling. This article...
Hardenability – the influence of tramp elements
Hardenability is the property of a material to deeply harden, and not the ability to get hard . This basic concept has driven much...
Vapor pressure of mineral oils
In this column, I will discuss vapor pressure of mineral oils, and how to calculate the vapor pressure as a function of temperature.
Introduction
As the...
Furnace Types
Heat treating furnaces consist of several subassemblies: insulation (fiber and brick), heating systems (electric and gas), material handling, quenching, atmosphere system, process and control...
Use of molten salts for martempering of steel
In July’s column, I talked about molten salts and the different types. In this short column, we discuss the benefits of using molten salts...
Revisiting the 1:1 Rule for oil quenchants
The rule of thumb “one gallon of oil to one pound of parts and fixtures” has been in the literature for a long time....
Troubleshooting induction hardening problems: Part 2
Last month, I began a two-part article about troubleshooting induction hardening problems and discussed possible corrections. This month, I will discuss biological and odor...
Thermal triplets: PM, sintering, and case hardening
From my experience, powder metals (PM), sintering, and case hardening are three processes that could be said to be joined at the hip. More...
Anatomy of a Heat-Treating System
Ninety-eight 600-pound trays are in continuous process, 13 are in the pre-process queue, nine preheating, 14 in the boost carb, eight in the diffusion...
