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Materials Engineering Lab – ME 251 Lab #11: Jominy End-Quench Test Section: Monday-12.30pm Student’s Name :Ravi Raushan Instructor: Dr. Eylem Asmatulu

Experiment Date: 04/17/2017 Due Date: 04/28/2017

Why is hardness important? Hardness is the property of a material that enables it to resist plastic deformation penetration, indentation, and scratching. Therefore, hardness is important from an engineering standpoint because resistance to wear by either friction or erosion by steam, oil, and water generally increases with hardness.

What is hardenability? Where is it used in industry? The ability for steel to form martensite at different cooling rates. Hardenability represents the ease of martensite formation or the necessary cooling rate, as it is easier to cool slowly. This helps metallurgists create the proper procedures needed for the engineer to achieve the desired properties for a component. Hardenability is shown as a curve of hardness plotted against cooling rate. One of the important properties of (processed) metals is hardenability. Hardenability is the capability of an alloy to be hardened by heat treatment. Measures the depth of hardness obtained by heat treatment/quenching. Hardenability is not the same as hardness.

Hardenability is a measure of the capacity of a steel to be hardened in depth so industrial uses are 

Hardenability of steels for oil industry

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Determining materials for the mining industry

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Hardenability is the property that determines the depth and distribution of hardness induced by quenching.

Do all steels have the same hardenability? Why or Why not? Information gained from this test is necessary in selecting the proper combination of alloy steel and heat treatment to minimize thermal stresses and distortion when manufacturing components of various sizes. The Jominy test shows how different metals behave when quenched, and their ability to increase hardness. Useful because even though steel is very similar with iron and carbon, small alloying elements can have a big change.

How does the hardness change as a function of distance from the quenched end?

Shown above is a picture which demonstrates how Hardness changes as a function of distance from the quenched end. Mainly because, the cooling rate varies with the position

How does grain size relate to hardness? What would a graph of grain size as a function of distance look like? “Microscopy” – Grain size is a contributing factor to hardness and hardenability. Micrographs can be

Hardness, HRC

taken and grain size measured for another quantitative test.

Distance from quenched end 1. Determine a metal’s hardenability with the Jominy End-Quench Test The Jominy End-Quench test determines hardenability of any variety of steel, and is straightforward due to its simplicity and minimization of variables. The size and shape of the sample are standardized as well as the quench process, so the extent of martensite formation can be compared quantitatively between different steels. And since steels have similar thermal conductivity, the distance from the quenched end correlates to a certain cooling rate. Knowing this, the hardness of a metal cooled at a given cooling rate can be accurately predicted from the Jominy test results.

2. Create and interpret a hardenability curve JOMINNY SAMPLE Distance (in) 0.125 0.25 0.375 0.5 0.75 1 1.25 1.5 1.75 2

Hardness 4140 56 55 52 51 48 46 43 40 38 34

Rockwell C, 1045 54 30 28 27 24 23 19 15 15 13

Distance vs 4140 and 1045 60

Hardness Rockwell C

50 40 Y-Values Column1

30 20 10 0

0

0.5

1

1.5

2

2.5

Distance, (in)

From the graph shown above, Plotting hardness against quenched end distance shows hardenability curves for the sample. Note that the 4340 Steel data shows that it can be cooled slowly and still form martensite while 1040 steel needs to be cooled rapidly to form martensite. This shows that 4340 has a higher hardenability.

Reference Lab Manual...