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 – 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...
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...
Find the right equipment
Vacuum carburizing or LPC, neutral hardening, oil or HPGQ (high pressure gas quench), vacuum pumps, graphite insulation, radiation shields or ceramic insulation, graphite or...
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...
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...
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...
Finding data needed for modeling and simulation
Modeling and simulation have become an important part of the design and manufacturing toolbox. Modeling and simulation are used in forging, casting, machining, forming,...
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...
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...
Effect of temperature on oxidation of oil quenchants
In this column, I will discuss the effect of temperature on the oxidation behavior of martempering oil used for distortion control.
Introduction
Martempering oils are used...
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...
Meeting Automotive Efficiency Standards
For automobiles where competing hardening processes and materials are involved, automotive designers and heat treaters have choices when deciding how to meet efficiency standards.
There...
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...
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...
Furnace Maintenance
When a heat treat manager or anyone responsible for purchasing heat treating equipment makes a buy decision, they must first consider the process required,...
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...
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...
Quenching from molten salt into polymer quenchants
In this column, I will discuss quenching aluminum from molten salt into a polymer quenchant.
A molten salt bath is a common method of heating...
Troubleshooting induction hardening problems – Part III
In previous columns, I have provided some detail on the sources of problems with induction hardening. While I have tried to be inclusive, there...
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...
How did we get where we are today?
Having worked in the heat-treating industry for 58 years, I agreed in January 2011 to write a monthly column about all things heat-treating for...
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...
Heating with natural gas
It’s no secret that the heat treating industry is one of the major recipients of the impact when the U.S. Environmental Protection Agency (EPA)...
Heat-treating workhorse – integral quench furnace
In this column, we will discuss the workhorse of the steel heat-treating industry – the integral quench furnace.
The integral quench furnace, or sealed quench...
Allocating space for case hardening furnaces
When selecting neutral or case hardening furnaces that require pits and have vertically mounted radiant tubes, facility managers must make sure that the equipment...
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...
Compatibility of polymer quenchants with metals, seals
In this column, I will discuss the compatibility of polymer quenchants and materials used in the construction of quench tanks, heat exchangers, and pump...
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 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...
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...
Future of heat treating of gears is similar to garage sale mentality
When and how does a heat treater determine whether to purchase new equipment or rebuild an old furnace?
Several years ago I participated in a...
Let’s hear it for welding
Heat-treating and metallurgy are topics that attract the overwhelming interest of attendees of technical conferences and are written about in numerous articles. However, a...
The big gamble: Electric vehicles or bust
There’s a big gamble going on in Detroit, and I don’t mean at Greektown Casino; it’s at the big three automakers. All have, in...
Thermal separation of polyalkylene glycol quenchants
Polyalkylene glycol quenchants are used in a variety of different heat-treating applications. One very common application is quenching of large steel and aluminum components....
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...
Carburizing today: The secrets to predicting success
Predicting the outcome for today’s various carburizing processes requires different procedures and processes.
Carburizing today is performed by two primary processes, at or above atmospheric...
The effect of agitation on oil quenchants
In this column, I will discuss the effect of agitation on the cooling curve of oil quenchants.
Oil has been used for many years as...
Some things old can be new again
Why heat-treating furnaces look the way they do
Quench Factor analysis used to predict properties of quenched and aged aluminum
In this column, we will start to discuss the application of Quench Factor Analysis (QFA) to predicting properties of quenched and aged aluminum.
Quench Factor...
