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.
|Country:||United Arab Emirates|
|Published (Last):||19 August 2006|
|PDF File Size:||10.74 Mb|
|ePub File Size:||19.67 Mb|
|Price:||Free* [*Free Regsitration Required]|
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.
In other projects Wikimedia Commons. Cooling hest some well circulated oil is less efficient, the bar diameter goes down to about 6 cm violet line.
The hardenability of ferrous alloys, i. Adopted from a ” Key to Metals ” article. If the fluid is agitated cooling occurs even more quickly. Three medium carbon steels 0. This alternative longer video clip contributed by Oxford Brookes University shows both the transfer of the sample from furnace to Jominy machine, and the jet spraying one end of the sample.
It is then carefully and quickly moved to the quenching machine and positioned above a water jet. Again, you text three steels. The cold region has transformed from austenite to a mixture of martensite, ferrite and pearlite.
The indentor is either a conical diamond pyramid, or a hardened steel ball. The test sample is quickly transferred to the test machine, where it is held vertically and sprayed with a controlled flow of water onto one 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.
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. This requires the addition of “gettering” elements such as aluminium and titanium to react preferentially with the oxygen and nitrogen in the steel.
Structure of En 24 at 10 cm position along Jominy bar, furthest from the quenched end.
The Jominy End Quench Test
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. This results in a progressive decrease nominy the rate of cooling along the bar from the quenched end.
The variation of hardness was measured with distance from the quenched end. The fluid jmoiny for quenching the material influences the cooling rate due to varying thermal conductivities and specific heats. Carbon controls the hardness of the martensite. The size of the time step is set to the maximum allowed while ensuring numerical stability of the simulation. The resultant microstructure is quite coarse, with reduced toughness and ductility.
You have three steels. Knowledge of the jomiiny of steels is necessary in order to select the appropriate combination of alloy and heat tedt for components of different size, to minimise thermal stresses and fest. Select the most appropriate steel to achieve the necessary levels of mechanical properties, residual stress and distortion in a 1mm diameter wood-working drill. Structure of En 8, 1 cm from quenched end of Jominy bar. Slow quenching speeds are often chosen to reduce distortion and residual stress in components.
The Rockwell hardness of a metal can also be determined using a similar technique. You can also use jjominy Jominy test for checking the efficiency of your cooling fluid. The water jet is started and sprayed onto the bottom of the specimen until the specimen is cool. Example Jominy end quench test data A plain carbon steel and an alloy steel were assessed using the Jominy end quench test. It’s important to use the correct conversion chart for different materials, since the hardness test causes plastic strain, and therefore varies with the strain hardening properties of the material.
Your browser does not support the video tag.
DoITPoMS – TLP Library The Jominy End Quench Test
Teet Test and Hardness Depth. This information is plotted on a hardenability graph. The interval is typically 1. Structure of En 8 at the quenched end of Jominy bar.