ASTM D(). Standard Test Method for Rockwell Hardness of Plastics and Electrical Insulating Materials. standard by ASTM. This standard is issued under the fixed designation D ; the number 1 This method is under the jurisdiction of ASTM Committee D20 on Plastics and. ASTM A/AM() Composite Ribbed Steel Pipe, Precoated and Polyethylene Lined for Gravity Flow Sanitary Sewers, Storm Sewers, and Other.
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A Rockwell hardness number is a number derived from the net increase in depth impression as the load on an indenter is increased from a fixed minor load to a major load and then returned to a minor load Procedure A.
Indenters are round steel balls of specific diameters. Rockwell hardness numbers are always quoted with a scale symbol representing the indenter size, load, and dial scale used.
Rockwell Hardness ASTM D785, ISO 2039
This test method is based on Test Methods E Procedure A Section 11 yields the indentation of the specimen remaining 15 s after a given major load is released to a standard kg minor load. Procedure B Section 12 yields asttm indentation of the indenter into the specimen after a s application of the major load while the load is still applied.
Each Rockwell scale division represents 0.
In practice, the Rockwell hardness number is derived from the following relationship:. A Rockwell hardness number is directly related to the indentation hardness of a plastic material, with the higher the reading the harder the material.
Due to a short overlap of Rockwell hardness scales astk Procedure A, two different dial readings on different scales may be obtained on the same material, both of which may be technically correct.
For d78508 types of materials having creep and recovery, the time factors involved in applications of major and minor loads have a considerable effect on the results of the measurements. The results obtained by this test method are not generally considered a measure of the abrasion or wear resistance of the plastic materials in question. Indentation hardness is used as an indication of cure of some thermosetting materials at room temperature.
Norma ASTM D()
Generally, an uncured specimen has a hardness reading below normal. Each Rockwell hardness scale in Table 1 is an extension of the proceeding less severe scale, and while there is some overlap between adjacent scales, a correlation table is not desirable.
Readings on one material may be satisfactory for such a table, but there is no guarantee that other plastic materials will give corresponding readings because of differences in elasticity, creep, and d785–08 characteristics.
Before proceeding with this test method, reference should be made to the specification of the material being tested.
If there are no material specifications, then the default conditions apply. The values given in brackets are for information only. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Note 1—This test method and ISO are equivalent. Procedure A of this test method is equivalent to the test method in the main body of ISO Procedure B of this test method is equivalent to the test method in the integral annex part of ISO In practice, the Rockwell hardness number is derived from the following relationship: