JOMINY END QUENCH TEST PDF

The Jominy end quench test [1][2] ASTM A [3] is an extremely simple and useful test that is applicable to many materials besides steel [4][5]. This test can provide basic information on the hardenability of a material and be used for specifying incoming material for heat treatment. It can also be used to predict the expected hardness of an as-quenched heat-treated part [6] as well as specifying materials during initial product design [7]. The Jominy end quench test consists of a simple bar 25 mm in diameter by mm long.

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The Jominy end quench test [1][2] ASTM A [3] is an extremely simple and useful test that is applicable to many materials besides steel [4][5]. This test can provide basic information on the hardenability of a material and be used for specifying incoming material for heat treatment. It can also be used to predict the expected hardness of an as-quenched heat-treated part [6] as well as specifying materials during initial product design [7]. The Jominy end quench test consists of a simple bar 25 mm in diameter by mm long.

A small flange is machined at the end of the specimen for support. The bar is heat treated at normal austenitizing temperatures for the specific alloy for approximately one hour. The specimen is removed from the furnace, and hung in a special fixture Figure 1. As soon as the specimen has been hung in the fixture, a water valve is turned on, allowing water to cool the bottom of the specimen the quenched end.

A gradient of quench rates occurs along the length of the sample, with the quenched end exhibiting the highest quench rate and distances away from the quenched end showing progressively slower quench rates Figure 2. Once the specimen has cooled, two flats the length of the specimen are machined on opposite sides of the bar. This data is then plotted as a function of distance from the quenched end.

An example of the Jominy end quench plots for several alloys is shown in Figure 3. In Figure 3, it can be observed that, at identical quench rates or distance from the quenched end of the Jominy end quench specimen , the hardness of each of the alloys is different. This very clearly shows the differences in hardenability of the different alloys. There will be a range of Jominy data depending on the chemistry of the alloy. This is illustrated in Figure 4.

This data can be useful for determining the minimum hardenability needed for parts. To determine this, it would be necessary to consult the Lamont [8] charts. In these charts, the hardness of round bars of different thickness is correlated to the Jominy end quench data Figure 5. For instance, if the needed as-quenched hardness at the center of a 2. One of the drawbacks of this is the value of the Grossman H-value [9].

Often it is not known. However, it usually can be determined from cooling curve data or from your oil supplier. This will be the subject of another article. Assuming that the Grossman H-Value is known either from calculation or from the quenchant supplier, this data can be used to predict the expected hardness, or to select an alloy to be used for a possible part. From Figure 5, the surface hardness would correspond to J4, and the center hardness would correspond to J9.

A tabulation of Jominy end quench data would be examined [10], and an alloy would be chosen that satisfies the required surface and center hardnesses at those distances from the quenched end. In the same fashion, after a material has been chosen, the data can also be used to select a quenchant to be used to achieve the desired surface and core properties.

This is useful to ensure that, once the part has been designed, it can be manufactured and not be prone to cracking or distortion. In this short article, the Jominy end quench test has been described. The method of conducting the test has been briefly discussed. The practical application of the data provided in the Jominy end quench test to specifying minimum hardenability requirements for incoming material for heat-treated parts was illustrated using Lamont charts.

The selection of material for a part, based on the center and surface hardness, and a typical quenchant were also illustrated. In summary, the Jominy end quench test is a powerful and data-rich test method that can be used by heat treaters, quality engineers, and designers to ensure that a part is made to specification.

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Understanding the Jominy end quench test

For example, any video clips and answers to questions are missing. The formatting page breaks, etc of the printed version is unpredictable and highly dependent on your browser. 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 TLP considers the basic concepts of hardenability and the Jominy test. Knowledge about the hardenability of steels is necessary to be able to select the appropriate combination of alloy steel and heat treatment to manufacture components of different size to minimize thermal stresses and distortion. The Jominy end quench test is the standard method for measuring the hardenability of steels.

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Understanding the Jominy End-Quench Test

Before the specimen is machined and quenched, it must be normalised. The surface of the specimen must be precision-turned and the end to be quenched precision machined. The end surface must be burr-free. One the specimen has been produced, it must be evenly heated up to the temperature defined in the standard over a period of at least 20 minutes and then held at the prescribed temperature for at least 30 but not more than 35 minutes. Carburisation or decarburisation of the specimen should be kept as low as possible, and oxidation with scale formation should be avoided. The time between the removal of the specimen from the furnace and the start of quenching must not be longer than five seconds. For quenching, a testing device is used see figure further below that allows the water jet to abruptly strike the end face of the specimen to be quenched.

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