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ME 328 HARDENABILITY LABJOMINEY END QUENCH TESTSEYI ADENIYANEMAIL: [email protected]
SAFETYGeneral SOP must be adhered to
All phones switched off
Good housekeeping
Emergency exit doors
All students must appear in appropriate PPE
HARDENABILITY Hardenability is the ability of an alloy to be hardened by the formation of martensite
as a result of a given heat treatment.
Hardenability test is used to determine the influence of alloy composition on the
ability of steel alloy to transform to martensite for a particular quenching treatment.
Remember: Hardenability is not Hardness!
JOMINY END QUENCH TEST
TEST PROCEDURE1. The specimen is austenitized at a prescribed temperature for a prescribed time.
2. The specimen is quickly removed from the furnace.
3. Then it is placed into Jominy End Quench unit.
4. The lower end is quenched by a jet of water with the specific flow at 24˚C.
5. After cooling to the room temperature, the specimen is ground along the length.
6. The Rockwell hardness measurements are made: 1/16 in intervals for the first 1/2
in and 1/8 in intervals for the remaining 1.5 in.
7. The hardenability curve is obtained when the hardness is plotted as a function of
position from the quench end.
HARDENABILITY CURVECooling rate decreases,
hardness decreases
(100% Martensite)Quench end is cooled most rapidly, maximum hardness
EFFECT OF ALLOY COMPOSITION ON STEEL
Plain Steel (0.4% wt Carbon)
Alloy steels (0.4% wt Carbon),
different alloying element
Identical hardness at quenched end
Hardness is function of carbon content
Low hardenabilityHardness drops sharply after
a short Jominy distance
Gradual decreases in hardness
More hardenability
Quenched end(Cooling rate 600˚C) 100% Martensite
Pearlite with proeutectoid Ferrite
Mixture of Martensite and Bainite
Effect of Carbon Content
The hardness at any Jominy position increases with the concentration of
Carbon
The hardenability curves depend on :carbon content
Microstructure and Indentation point on the Sample Specimen
1045 Steel (300 gf)Reading Distance
from end (mm)
D1 D2 D ave. VHN Approx. HRC
1 1.6 29.34 28.63
2 3.2 30.75 30.68
3 4.8 32.27 31.66
4 6.4 40.67 38.68
5 8 43.14 42.81
6 9.6 44.22 44.36
7 11.2 44.38 44.9
8 12.8 45.83 45.49
9 16 45.82 45.71
10 19.2 46.3 46.71
11 22.4 46.49 46.44
12 25.6 46.69 46.42
13 28.8 47.68 45.79
14 32 47.24 47.38
15 35.2 47.71 46.69
16 38.4 47.38 48.12
17 41.6
18 44.8
19 48
TABLE OF VALUES