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Ref. No.: ISO/RW-l959(E)
IS0
I NT ERN AT I ON A L FOR STA N DARD I Z AT I O N
ORGAN I Z AT I ON
RECOMMENDATION
RocKLS~LL HARDNESS TEST -7
(B AND c SCALES)
copyright of IS0 Recommendations and IS0 Standa
to IS0 Member Bodies. Reproduction of
ocuments, 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 80, Rockwell Hardness Test (B and C Scales)
for Sfeel, was drawn up by Technical Committee ISO/TC 17, Steel, the Secre-
tariat of which is held by the British Standards Institution (B.S.I.).
At the first meeting of ISO/TC 17, held in London, in June 1950, the
Secretariat submitted a first draft proposal for the Rockwell hardness test,
based on a document which had been drawn up by the former International
Federation of the National Standardizing Associations (ISA). The Technical
Committee instructed its Working Group No. 1, Methods of Mechanical Testing
/or Sieel, to examine this draft proposal and to prepare a new version of it,
taking into account certain observations put forward by Member Bodies.
In February 1952, the Working Group submitted a second draft proposal,
which was discussed at the second plenary meeting of ISO/TC 17, held in New
York, in June 1952, and which was passed back to the Working Group so that
it might include therein data on tolerances.
The third draft proposal, submitted by the Working Group in August 1953,
was studied by the Technical Committee during its third plenary meeting, held
in London, in December 1953, along with the comments of the Member Bodies.
The ISO/TC 17 Secretariat was then assigned to draw up a fourth draft proposal
incorporating the changes voted during the meeting, and this was circulated
in April 1954.
of the Member Bodies on this fourth draft proposal were
The comments
discussed at the fourth plenary meeting, held in Stockholm, in June 1955, and
the Technical Committee decided to adopt it, subject to a few amendments, as
a Draft IS0 Recommendation.
On 28 September 1956, this Draft IS0 Recommendation (No. 119) was
distributed to all the IS0 Member Bodies and was approved, subject to a few
modifications of details, by the following Member Bodies :
*Australia France Pakistan
Poland
Belgium *Greece
._
Bulgaria Portugal
Hungary
*Canada *Ireland Spain
Chile Italy Sweden
Czechoslovakia Japan Switzerland
Denmark Netherlands U.S.S.R.
Finland Norway Yugoslavia
O e Member Body op osed the approval of the Draft: Austria.
The Draft IS0 Recommendation was then submitted by correspondence
accept it as an
to the IS0 Council, which decided, in February 1959, to
IS0 RECOMMENDATION.
* These Member Bodies stated that they had no objection to the Draft being approved.
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I
IÇO/R 80 - 1959 (E)
February 1959
IS0 Recommendation R 80
ROCKWELL HARDNESS TEST
(B AND C SCALES)
FOR STEEL
1. PRINCIPLE OF TEST
The test consists in forcing a penetrator of standard type (cone or ball) into
the surface of a test piece in two operations and measuring the permanent in-
crease e of the depth of indentation of this penetrator under conditions de-
fined later.
The unit of measurement for e is 0.002 mm, from which a number, known as
the Rockwell hardness, is deduced.
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2. SYMBOLS AND DESIGNATIONS
TABLE 1. - Test with diamond cone (Rockwell C)
Designation
Sumber Symbol
Angle at the tip of the diamond cone (120")
Radius of curvature at the tip of the cone
(0.20 mm)
Preliminary load = 10 kgf
Additional load = 140 kgf
Total load = Fo + FI = 10 + 140 = 150 kgf
Depth of indentation under preliminary load
before application of additional load
Increase in depth of indentation under additional
load
Permanent increase of depth of indentation
under preliminary load after removal of addi-
tional load, the increase being expressed in units
of 0.002 mm
Rockwell hardness C = 100 - e
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ISO/R 80 - 1959 (E)
TABLE 2. - Test with steel ball (Rockwell B)
Symbol Designation
&umber
Diameter of ball (1.587 5 mm or 1/16 in)
Preliminary load = 10 kgf
Additional load = 90 kgf
Total load = F, + FI = 10 + 90 = 100 kgf
Depth of indentation under preliminary load
before application of additional load
Increase in depth of indentation under addi-
tional load
Permanent increase of depth of indentation
'L under preliminary load after removal of addi-
tional load, the increase being expressed in units
of 0.002 mm
Ro
...