The Jominy end quench test. Introduction: The Jominy end quench test is used to measure the hardenability of a steel, which is a measure of the capacity of the. 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. PDF | 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.
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Look at both the microstructures at high magnification, and try to observe the relationship between the volume fraction of martensite and the hardness of the steel. The hardness of the samples was measured as a function of the distance from the quenched end to demonstrate the different hardenability of the two steels.
This results in a progressive decrease in the rate of cooling along the bar from the quenched end. Again, you have three steels. James Marrow University of Cambridge Content development: Similar tests have been developed in other countries, such as the SAC test, which uses a sample quenched from all sides by immersion in water.
Example Jominy end quench test data A plain carbon steel and an alloy steel were assessed using the Jominy end quench test. Knowledge of the hardenability of steels is necessary in order to select the appropriate combination of alloy and heat treatment for components of different size, to minimise thermal stresses and distortion.
Select the most appropriate steel to achieve the necessary levels of mechanical properties, residual stress and distortion in an injection moulding die for a mobile phone plastic case. The Vickers test is most commonly used in the UK.
Jominy End Quench Test
The Jominy Jokiny involves heating a test piece from the steel 25mm diameter and mm long to an austenitising temperature and quenching from one end with a controlled and standardised jet of water. Slower cooling rates occur at the core of larger components, compared to the faster cooling rate at the surface.
After quenching the hardness profile is measured at intervals from the quenched end after the surface has been ground back to remove any effects of decarburisation 0.
Select the plot of hardness variation along the test specimen that best describes their behaviour. En 8 is a low hardenability steel when compared with En The austenite grain size can be affected by other stages in the processing of steel, and therefore jomjny hardenability of a steel also depends on the previous stages employed in its production. The water jet is started and sprayed onto the bottom of the specimen jominh the specimen is cool.
DoITPoMS – TLP Library The Jominy End Quench Test
The proportions of the phases at any position depends on the cooling rate, with more martensite formed where the cooling rate is fastest. The furnace used to heat the steel into the austenite phase field. This data can be presented using CCT C ontinuous C ooling T ransformation diagrams which are used to select steels to suit the component size and quenching media. High carbon steels are prone to distortion and cracking during heat treatment, and can be difficult to machine in the annealed condition before heat treatment.
The effect of boron is also independent of the amount of boron, provided sufficient is added, and the effect of boron is greatest at lower carbon contents. The indentor is either a conical diamond pyramid, or a hardened steel ball. This animation requires Adobe Flash Player 8 and later, which can be downloaded here.
However, the effect is too small be be commonly used for control of hardenability.
The Jominy End Quench Test, ASTM A
Select the ttest appropriate steel to achieve the necessary levels of mechanical properties, residual stress quenh distortion in a 1mm diameter wood-working drill. High hardenability allows slower quenches to be used e. The nucleation of ferrite and pearlite occurs at heterogeneous nucleation sites such as the austenite grain boundaries. This is commonly jmoiny in the USA.
Measurement of hardenability Uses of Jominy data: As the water jet sprays onto the end of the hot, glowing specimen, a cold dark region spreads up the specimen. Boron has a very strong affinity for oxygen and nitrogen, with which it forms compounds. 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.
You have three steels. It is more common to control hardenability with other elements, and to use carbon levels of less than 0.
Carbon controls the hardness of the martensite. The formatting page breaks, etc of the printed version is unpredictable and highly dependent on your browser. Click on the circled data points to see how the microstructure varies with distance from the quenched end. The variation of hardness was measured with distance from the quenched end. Data from the Jominy end quench test can be used to determine whether a particular steel can be sufficiently hardened in different quenching media, for different section diameters.
For example, any video clips and answers to questions are missing. The retardation is due to the need for redistribution of the alloying elements during the diffusional phase transformation from austenite to ferrite and pearlite.
This describes the ability of the steel to be hardened in depth by quenching. Structure of En 24 at 5 cm position along Jominy bar. It is not only necessary to understand the basic information provided from the Jominy test, but also to appreciate how the information obtained can be used to understand the effects of alloying in steels and the steel microstructure.