Evaluating a material’s response during austenitization
Carbon content in steel has a direct correlation to the hardness and overall strength of a component after heat treatment. Carbon can take many...
Carburizing
While some heat treatments are used to soften the material or improve its machinability, most are processed to obtain strengthened or hardened properties. The...
Learning from failure in bending stress
A couple of years ago, as I was finishing my graduate studies, I was lucky enough to participate in the Strong Bar competition put on...
Cold expansion an efficient strengthening solution
In flight, aerospace components are in a state of constant cyclic stress. The term “flying fatigue machines” is commonly used by those in the...
Linear-elastic fracture toughness testing
Materials fracture occurs in all sectors of the economy — aerospace, nuclear, medical, transportation, oil and gas, petrochemical, commercial and residential buildings, etc. The...
Non-Martensitic Transformation Products (NMTP)
Whether formed during a conventional quench and tempering process, carburizing, or induction hardening, non-martensitic transformation products (NMTP) are widely considered undesirable microstructural features. However,...
Achieving results through cold treatment
Cold treatment is a sub-zero thermal treatment process primarily used to reduce the retained austenite content of alloy and high carbon steels. Cold treatment...
The meta-stable microstructure of martensite
In this column, we will discuss martensite and its formation.
Heat treating steel involves heating the component into the austenite range. Once the part is...
Variation in steel hardenability
Many heat-treating processes cannot tolerate appreciable variations in steel hardenability. For an established in-control process, deviations in chemical composition and starting microstructure may result...
Variation in Hardenability
Many heat-treating processes cannot tolerate appreciable variations in steel hardenability. For an established in-control process, deviations in chemical composition and starting microstructure may result...
How to keep decarburization in check
The performance of heat-treated steel components is largely dependent on the condition of their surface. Wear and fatigue resistance are examples of design criteria...
Carbon potential verification
Choose from several verification methods for best fit, then develop a plan to correct for out-of-spec test results
Stress modeling of the WAAM process
A thermal model was previously developed and executed to simulate the Wire Arc Additive Manufacturing (WAAM) process, using the Goldak Flux Distribution to model...
Hardness scale conversion
The use of hardness testing as a quality control method to check the outcome of a thermal treatment process is a common application of...
Evaluating effect of heat treat on flank slope profile deviation of steel gears using...
The finish machining of a gear is undoubtedly one of the most important manufacturing steps. It sets the geometry, surface condition, and residual stress...
From time/temperature to HTC
High-pressure gas quenching (HPGQ) involves quenching an austenitized part in an inert gas, resulting in a cleaner part and potentially reduced distortion compared to...
Compelling reasons normalizing produces high quality gears
In this day and age, adding steps to the gear manufacturing process is not highly desirable unless the benefits far outweigh the costs incurred....
Books on steel for metallurgists and heat treaters
There are many books, papers, and publications that metallurgists and heat treaters rely on to assist with heat treating, material selection, failure analysis, or...
Using welding simulation tools to model WAAM
In its simplest form, additive manufacturing has been used since before the common era where low temperature melting materials such as tin, silver, copper,...
Heat-treatment of modified 9CrMo steel
The modified 9CrMo steels, such as Grade 91, Grade 92, and HT9, are materials of choice for fossil-fuel-fired power plants and Next Generation Nuclear...
Press quenching tooling design using simulation
Steel powertrain gears are commonly carburized and quench hardened to improve strength and wear characteristics. However, solid-state phase changes occurring within the steel during...
Characterizing equipment using simple modeling tools
Often, the terms “digital twins” or ICME (Integrated Computer Materials Engineering) are used when talking about computer modeling of actual parts or the behavior...
Induction Hardening Choices for Gears
Of the various types of applied energy processing, induction hardening is the most common. Induction heating is a process that uses an alternating electrical...
Heat transfer: Convection’s reach
Many years ago, as a mechanical engineering undergraduate student, an analogy was offered to help explain the interplay between convection and conduction in heat...
Determining austenite grain size
Grain size is a critical metallurgical characteristic, significantly influencing design parameters such as strength and toughness. Austenite grain size (often referred to as prior-austenite...
Improving temperature uniformity during tempering
The final step in any steel heat-treatment quenching process which produces a martensitic microstructure is tempering. Martensite is a metastable phase and is extremely...
Why is modeling the immersion process so important?
Liquid quenching of long steel components can introduce significant distortion if the component is not lowered into the liquid quench bath properly. Whether the...
Carbon Diffusion and Carburizing Parameter Selection
Although carburizing is a complicated process, it can be broken down into two main steps: carbon generation in the furnace and carbon diffusion into...
Retained austenite significant for strength, toughness
The role of retained austenite (RA) and the magnitude of its influence on the performance of steel components are continually debated. Depending on the...
Stress evolution during quench hardening of steel
Quench hardening of steel components involves complex, nonintuitive phenomena, particularly as it relates to the dimensional changes and stresses induced. Figure 1 shows a...
Predicting strains key to evaluating heat-treat response
Quench hardening of steel components requires the components to be heated to a temperature such that the solid-state crystal structure of the material changes...
Integrating effects of heat treatment into loading models
Finite element analysis (FEA) is widely used in mechanical design to predict part performance under various loading conditions. However, traditional loading models often assume...
Fatigue failures in nickel-based austenitic Superalloy 718
Superalloy 718 is widely used for aerospace, nuclear, power generation, metal processing, medical, material processing, and chemical and petrochemical industries due to its excellent...
Heat treatment techniques overview
Editor’s note » This is the third in a five-part series.
In this third segment of my series on heat-treating techniques, I will discuss the pros and...
Kanthal APMT for nuclear-energy application
The major earthquake and tsunami that occurred in Japan in 2011 did serious damage to boiling water reactors of the Fukushima-Daiichi nuclear power plant....
Heat treatment techniques overview
Editor’s note » This is the fourth in a five-part series.
In this fourth installment of my series on heat-treating techniques, I will discuss the pros...
Low pressure carburization simulation of steel alloys with strong carbide forming elements
Low pressure carburizing (LPC) is quickly gaining popularity across many industries due to LPC’s reduced cycle time, lack of oxidation/decarburization at and near surface,...
Bending under pressure: Controlling distortion
Distortion from heat treatment is a main concern because heat treatment is often one of the last steps in the manufacturing process. Excessive distortion...
Carburizing Optimization & ECD Precise Control
As discussed in the September/October 2016 Metal Urgency column , carburizing is a nonsteady-state diffusion process and thus can be expressed by Fick’s second...
Combatting undesirable NMTP formations
Whether formed during a conventional quench and tempering process, carburizing, or induction hardening, non-martensitic transformation products (NMTP) are widely considered undesirable microstructural features. However,...
