JOMINY END QUENCH TEST PDF
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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Click on the circled data points to see how the microstructure varies with distance from the quenched end. Boron is a very potent alloying element, typically requiring 0.
The graph below gives the Jominy end quench data in terms of the Rockwell hardness number. The solubility of the elements varies between the different phases, and the interface between the growing phase cannot move without diffusion of the slowly moving elements. James Marrow University of Cambridge Jojiny development: In the example here, the surface jominh be transformed to martensite, but the core will have a bainitic structure with some martensite. 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.
Hardenability therefore describes the capacity of the steel to harden in depth under a given set of conditions. 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. This cools the specimen from one end, simulating the effect of quenching a larger enr component in water.
The most commonly used elements are Cr, Mo and Mn. Boron has a very strong affinity for oxygen and nitrogen, with which it forms compounds. This requires the wnd of “gettering” elements such as aluminium and titanium to react quencg with the oxygen and nitrogen in the steel. The Jominy end quench test is the standard method for measuring the hardenability of steels. This is commonly used in the USA. Structure of En 8 at the quenched end of Jominy bar.
The Jominy End Quench Test
Look at both the microstructures at jo,iny magnification, and try to observe the relationship between the volume fraction of martensite and the hardness of the steel. The cooling rate varies along the length of the sample from very rapid at the quenched end, to rates equivalent to air cooling at the other end. The furnace used to heat the steel into the austenite phase field.
The hardness variation along the test surface is a result of microstructural variation which arises since the cooling rate decreases with distance from the quenched end.
The Rockwell hardness test measures a number which depends on the difference in the depth of an indentation made by two loads, a minor load followed by a major load. Carbon controls the hardness of the martensite. Slow quenching speeds are often chosen to reduce distortion and residual stress in components.
There are quite complex interactions between the different elements, which also affect the temperatures of the phase transformation and the resultant microstructure. The indentor is either a conical diamond pyramid, or a hardened steel ball.
The recorded hardness depends on the indentation load and the width of the square indentation made by the diamond. James Marrow and Dave Hudson. The Vickers hardness test uses a square pyramidal diamond indentor.
The Jominy End Quench Test
Measurement of hardenability Uses of Jominy data: The data is shown as Vickers and Rockwell hardness. These include alloying elements and grain size. Effects of alloying and microstructure Example Jominy end quench test data Heat flow simulation Quench test simulation Summary Questions Going further.
A jet of water qufnch from the cone at the bottom, to touch the lower end of the sample. This describes the ability of the steel to be hardened in depth by quenching. Tedt hardness number is usually denoted by HV20 for H ardness V ickers 20 kg, for example. Quencj hardness is measured at intervals from the quenched end. Hardenability is the ability of a steel to partially or completely transform from austenite to some fraction of martensite at a given depth below the surface, when cooled under a given condition.
The simulation ignores the effect of heat loss from the sides of the specimen, i.