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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The initial red-hot state represents the austenitic condition and the enr cooling results in a variety of transformations that depend on the chemical composition of the steel. The hardness number is usually denoted by HV20 for H ardness V ickers 20 kg, for example. Your browser does not support the video tag.
The Jominy End Quench Test, ASTM A
The indentor is either a conical diamond pyramid, or a hardened steel ball. Structure of En 8 at 5 cm position along Jominy bar.
jkminy 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 steel sample is normalised to eliminate differences in microstructure due to previous forging, and then austenitised. The Vickers hardness test uses a square pyramidal diamond indentor.
Three medium carbon steels 0. This results in a progressive decrease in the rate of cooling along the bar from the quenched end. 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. Increasing the carbon content increases the hardness of steels up to about 0. The Rockwell test is commonly used in the USA. Jominy end quench test can also be used to demonstrate the effects of microstructure and alloying variables on the hardenability of steels.
Carbon controls the hardness of the martensite.
The results are plotted in the graph below. The interval is typically 1. The water jet is started and sprayed onto the bottom quenhc the specimen until the specimen is cool.
You have three steels. 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.
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 End Quench Test
env The graph below gives the Jominy end quench data in terms of the Rockwell hardness number. A high hardenability is required for through hardening of large components. The furnace used to heat the steel into the austenite phase field.
The effect of boron is also independent of the amount of boron, provided sufficient is added, and the joimny of boron is greatest at lower carbon contents. 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.
DoITPoMS – TLP Library The Jominy End Quench Test
The main alloying elements which affect jomiiny are carbon, boron and a group of elements including Cr, Mn, Mo, Si and Ni. Steels with high hardenability are needed for large high strength components, such as large extruder screws for injection moulding of polymers, pistons for rock breakers, mine shaft supports, aircraft undercarriages, and also for small high precision components such as die-casting moulds, drills and presses for stamping coins.
James Marrow University of Cambridge Content development: 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. Hardenability depends on the chemical composition of the steel and also be can affected by prior processing conditions, such as the austenitizing temperature.
Take a sample from the furnace and place it on the Jominy test fixtures and observe the cooling pattern.
Jominy End Quench Test
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. This cools the specimen from one end, simulating the effect of quenching a larger steel component in water. However, the effect is too enx be be commonly used for control of hardenability.