No Comments The Jominy end-quench test is used to measure the hardenability of a steel , which is a measure of the capacity of the steel to harden in depth under a given set of conditions. This article considers the basic concepts of hardenability and the Jominy test. So, we felt print readers needed a second look. If you want to take a look at the original, click here. Knowledge about the hardenability of steels is necessary to select the appropriate combination of alloy steel and heat treatment to minimize thermal stresses and distortion in manufacturing components of different sizes. The Jominy end-quench test is the standard method for measuring the hardenability of steels.
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Bhadeshia A heat treatment that causes steel to harden is so much more than the meer plunging of hot metal into a fluid that is often a liquid. The initial red-hot state represents the austenitic condition and the subsequent cooling results in a variety of transformations that depend on the chemical composition of the steel.
If the intention is to produce a martensitic structure, then the constituents of the steel must be such that the phase is obtained over the depth required. The Jominy test provides a measure of the ability of a steel to harden by transforming into martensite under set conditions, i. A standardised bar, This results in a progressive decrease in the rate of cooling along the bar from the quenched end.
The depth from the quenched end, over which martensite is obtained, is then the measure of hardenability. Jominy end quench unit for testing the hardenability of steels Here a specimen is in place. A jet of water emerges from the cone at the bottom, to touch the lower end of the sample.
The sample. The furnace used to heat the steel into the austenite phase field. Safety equipment.
The Jominy End Quench Test
Generation of Jominy Curve 4. Hardenability Bands 5. Calculation of Jominy Curve from Composition in Steels. From the practical stand-point, however, this method of quenching a series of rounds is laborious, difficult and expensive. This is particularly so with increasing hardenability, since the number of pieces to be prepared, quenched, sectioned and hardness-traversed become large. Moreover, rounds of sufficient diameters of that steel are not always readily available.
Depth to which a metal is hardened after being submitted to a thermal treatment Jominy test dimensioning. Used Jominy test-piece. Example Jominy results. The hardenability of a metal alloy is the depth to which a material is hardened after putting it through a heat treatment process.