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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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?
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).
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?
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?
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.
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?
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.
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.
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.
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.
