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. Jominy Test and Hardness Depth. Thanks to Walter Jominy (the Chief Metallurgist of Chrysler Corporation sometime before the war), there is a simple but. 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.
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Effects of alloying and microstructure Example Jominy end quench test data Heat flow simulation Quench test simulation Summary Questions Going further. Cooling in some well circulated oil is less efficient, the bar diameter goes down to about 6 cm violet line.
The cooling rate will be different from one end to the other of the sample, and all you do after it has cooled down completely, is to measure the hardness along its length. Select the plot of hardness variation along the test specimen that best describes their behaviour. The austenite grain size can be affected by other stages in the processing of steel, and therefore the hardenability of a steel also depends on the previous stages employed in its production.
This animation requires Adobe Flash Player 8 and later, which can be downloaded here. Assume that a steel bar with a certain diameter is cooled completely in a medium as shown.
Alloying Elements in Detail. The Jominy end quench test is the standard method for measuring the hardenability of steels. The size of the time step is set to the maximum allowed while ensuring numerical stability of the simulation. Jominy end quench test can also be used to demonstrate the effects of microstructure and alloying variables on the hardenability of steels. Your browser does not support the video tag.
Retrieved from hominy https: The cooling jokiny varies along the length of the sample from very rapid at the quenched end, to rates equivalent to air cooling at the other end. Boron is a very potent alloying element, typically requiring 0.
Structure of En 24 at 10 cm position along Jominy bar, furthest from the quenched end. The proportions of the phases at any position depends on the cooling rate, with more martensite formed where the cooling rate is fastest. Take a sample from the furnace and place it on the Jominy test fixtures and observe the cooling pattern. This results in a work-piece that does not have the same crystal structure throughout its entire depth; with a softer core and harder “shell”. 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.
DoITPoMS – TLP Library The Jominy End Quench Test
En 8 is a low hardenability steel when compared with En However, the effect is too small be be commonly used for control of hardenability.
Hardenability depends on the chemical composition of the steel and also be can affected by prior processing conditions, such as the austenitizing temperature. 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.
A typical plot of hardness along the length of the 10 cm long steel rod. This describes the ability of the steel to be hardened in depth by quenching.
The hardenability depends on the alloy composition of the steel, and can also be affected by prior processing, such as the austenitisation temperature.
It should not be confused with hardnesswhich is tdst measure of a sample’s resistance to indentation or scratching. The interval is typically 1. Manufacturing Engineering and Technology. As the water jet sprays onto the end of the hot, glowing specimen, a cold dark region spreads up the specimen.
Jominy End Quench Test
This requires the addition of “gettering” elements such as aluminium and titanium to react preferentially with the oxygen and nitrogen in the steel. Jomiby of En 24 at 5 cm position along Jominy bar.
Views Read Edit View history. Plain carbon steel with sufficient carbon e. A jet of tesg emerges from the cone at the bottom, to touch the lower end of the sample. The Jominy Test 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. General Remarks to Literature and Sources. Retrieved 9 December Structure of En 8 at joominy cm position along Jominy bar.
Structure of En 8, 1 cm from quenched end of Jominy jojiny. 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.
This method of increasing the hardenability is rarely used since substantial increases in hardenability require large austenite grain size, obtained through high austenitisation temperatures.