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UDC 669.14:620.17: 621.785 Ref. No.: IÇO/R 642 - 1967 (E)
IS0
I NTERN AT1 ON A L O RG A N I Z AT I O N FO R STAN DA R D I ZATl O N
IS0 RECOMMENDATION
R 642
HARDENABILITY TEST BY END QUENCHING STEEL
(JOMl NY TEST)
1st ED IT1 ON
December 1967
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 642, Hardenability test by end quenching steel (Jominy test),
was drawn up by Technical Committee ISO/TC 17, Steel, the Secretariat of which is held by the
British Standards Institution (BSI).
Work on this question by the Technical Committee began in 1958 and led, in 1965; to the
adoption of a Draft IS0 Recommendation.
In January 1966, this Draft IS0 Recommendation (No. 919) was circulated to all the IS0
Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial
nature, by the following Member Bodies:
Argentina France Romania
Australia Germany Spain
Austria
Hungary Sweden
Belgium India
Switzerland
Brazil Israel Turkey
Canada Italy U.A.R.
Chile Japan United Kingdom
Czechoslovakia Korea, Rep. of U.S.A.
Denmark
Netherlands Yugoslavia
Finland Norway
No Member Body opposed the approval of the Draft.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0
Council, which decided, in December 1967, to accept it as an IS0 RECOMMENDATION.
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ISO/R 642 - 1967 (E)
.
IS0 Recommendation R 642 Decem ber 1967
HARDENABILITY TEST BY END QUENCHING STEEL
(JOMINY TEST)
1. PRINCIPLE OF TEST
The test consists in
heating a test piece to a given temperature for a specified period of time;
1.1
1.2 cooling it by spraying water on its end;
either assessing the hardness between two selected points, or measuring it at certain given
1.3
points along its length, in order to determine the hardenability of the steel by variations
of this hardness.
i
2. SYMBOLS AND DESIGNATIONS
I
Reference
Value
Symbol ' Designation
number
~
100 f 0.5 mm
1 Total length of test piece
25 f 0.5 mm
Diameter
2
3 Time during which the test piece is main-
30 f 5 minutes
tained at the heating temperature
Maximum time lag between removal of
4
the test piece from the furnace and the
5 seconds
start of quenching
5 to 30°C
Temperature of the cooling water
5
Internal diameter of vertical water supply
6
t
12.5 f 0.5 mm
Pipe
Height of water jet without test piece in
7
65 f 10 mm
position
Distance from tip of nozzle to the bottom
8
12.5 A= 0.5 mm
of test piece
Depth of flats for the measurement of
9
0.4 mm*
hardness
d Distance in millimetres from points where
10
mm
hardness is measured to quenched end
J xx-d Jominy hardenability index at distance d in Rockwell HRC-mm
11
in Vickers HV 30-mm
ditto
11 a J HVxx-d
* In certain cases, the product specification may require a greater depth.
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ISO/R 642 - 1967 (E) ,
3. TYPE OF TEST PIECES AND THEIR PREPARATION
3.1 Dimensions of the test piece
3.1.1 The test piece consists of a round bar machined to 25 mm diameter and 100 mm long.
3.1.2 The unmachined end of this test piece* is 32 or 25 mm in diameter depending upon
whether the test piece has a flange or an undercut (so as to permit rapid centralizing and
fitting into place, at the time of quenching, by means of an appropriate support (see
Fig. 1)).
3.1.3 The test piece should, if necessary, be marked (on the opposite end to the end to be
used for hardening) to enable the position to be identified in relation to the original bar.
d
3.1.4 Such marking is necessary, in particular, when the steel under consideration has only
a low depth of hardness and the hardenability of the material between the centre and
the surface of bars greater than 50 mm in side or in diameter has to be determined.
In this case, the test piece is generally taken from the bar in such a manner that its axis,
parallel to the axis of the bar, is situated midway between the centre and the surface.
The flats specified in clause 6.1 can then be made so that the material situated approxi-
mately at the same distance in the bar as the axis of the test piece is under investigation.
3.2 The forged or rolled test pieces are given a normalizing treatment before final machining.
For special requirements other heat treatments can be used.
3.2.1 In cases where it is of special interest to know the hardenability of the steel in the sof-
tened condition, the test piece may be treated accordingly.
3.2.2 Except by special agreement, the normalizing treatment should be carried out under
conditions specified in the product specification for the steel.
The rough bar should be treated so that the machined test piece is completely free from
3.2.3
decarburization, even from traces thereof.
3.3 The cylindrical surface of the test piece is machined by fine turning; the surface of the test
piece end to be hardened should have a reasonably fine finish, preferably obtained by
further polishing.
* Depending upon the dimensions of the sample bar from which the test piece is taken, the rough bar can be reduced to
It can also be obtained directly by casting; in this case, it is cast at the same
the above dimensions by rolling or forging.
time as the cast sample is taken, and this is taken at the end of the steelmaking process.
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ISO/R 642 - 1967 (E)
4. APPARATUS
The apparatus consists of a device for hardening the test piece.
4.1 The hardening device, shown in Figure 3, page 10, consists essentially of a means of fixing
and centralizing the test piece placed vertically above the water supply pipe. The water
supply pipe contains a quick action tap.
The relative positions of the end of the water supply pipe (12.5 & 0.5 mm internal dia-
4.2
meter) and of the test piece support should be such that the distance between the end of
the water supply pipe and the test piece face to be hardened should be 12.5 f 0.5 mm
(see Fig. 3).
4.3 The test piece support should enable precise centralizing of the test piece above the end of
the water supply pipe and the holding of it during spraying. It should be dry while the
test piece is being placed in position; splashing of water should be kept away from the test
piece while it is being placed in position and before the actual quenching operation starts.
c
The height of the water jet above the end of the water supply pipe without the test piece in
4.4
position should be 65 f 10 mm* (see Fig. 4). The water temperature in the pipe should be
between 5 and 30°C.
4.5 The hardening device should be protected from draughts.
5. TEST REQUIREMENTS
Heating of the test piece
5.1
5.1.1 The test piece is heated uniformly and then maintained for 30 & 5 minutes at the spe-
cified temperature (see product standard or special agreement). For particular types of
furnaces, this duration can be laid down as a result of previous experience establishing
the minimum time necessary for the centre of the piece to reach the desired temperature
(this temperature can be verified by means of, for example, a thermocouple placed in
a hole drilled along the axis of the test piece at the head end).
L
5.1.2 Precautions should be taken to avoid any decarburization of the test piece, or its
carburization or a marked oxidation with formation of scale. For example, a furnace
with a controlled atmosphere can be used or the test piece can be placed in a mild
steel vessel, as shown in Figure 2, page 9. The bottom of this vessel should be
covered either with graphite granules or with cast iron shot on which the test piece
will rest.
5.2 Hardening of the test piece
5.2.1 The time between removal of the test piece from the furnace and the commencement of
spraying should not exceed 5 seconds.
5.2.2 The water supply tap should open rapidly.
5.2.3 The time of spraying should be at least 10 minutes. After this time, the cooling of the
test piece can be completed by immersing it in cold water.
* To determine the force of the water jet, the dimension of the circle covered by water diverted by the test piece and falling
on a horizontal plane 60 mm below the end of the pipe can be measured. The diameter of the moistened circle should
be 210 mm.
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ISO/R 642 - 1967 (E)
1
O. PREPARATION FOR AND MEASUREMENTS OF HARDNESS AFTER HARDENING
6.1 Two flats for measuring the hardness are ground on the surface 180" apart along the entire
length of the hardened test piece.
They should be 0.4 mm deep. These flats are made
with an abundant supply of coolant so as to avoid overheating likely to modify the
micrographic structure of the test piece.
6.2 It should be ascertained that no softening by grinding has taken place as follows: immerse
the test piece in a 5 per cent v/v nitric acid solution in water until it is completely blackened.
After washing in hot water, the test piece should be immersed for 2 or 3 seconds in a 50 per
cent v/v hydrochloric acid solution in water; it should then be rewashed in hot water and
dried in an air blast. The colour obtained should be uniform.
If the
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