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Close attention needed when ASTM A48 is specified.

The following is an alert from the quality Control Committee of the Cast Iron Division of AFS to iron foundrymen regarding a problem with ASTM A48, one of the most commonly used gray iron specifications.

ASTM A48 is the specification used for specifying gray iron castings when the tensile strength of the iron is to be the criteria for acceptance of the metal. This specification describes how to conduct a tensile test with regard to the mold material, the tensile bar mold design and its gating system, the tensile bar size in relation to the size of the casting and the testing frequency.

The required test frequency is a major problem of which most foundrymen aren't aware. The specification requires a tensile test for each casting lot, as well as describing a lot (see sidebar included). The definition is, at best, confusing. if it is read in the context of a possible product liability suit, foundrymen will realize that they are not testing their iron as frequently as they should.

The problem is even more extensive than it appears because many companies use in-house requirements that reference the A48 specification. The tensile bar description in A48 has become the standard for the industry and companies have included a meaningless term in many of their specifications. The statement, "Test bars representing castings conforming to ASTM A48 shall meet requirements ....... may mean they are simply requiring the bar dimensions in A48, but, unless it is specified elsewhere, such a statement can be interpreted such that the frequency of tests required in A48 is also applicable.

The most obvious solution to this problem is to correct the specification, and to that end the appropriate ASTM committee is presently working. Because of the wide use of ASTM specifications, the change procedures are arduous. In order to give all affected parties an opportunity for input, a great deal of time is necessary to make changes. A quick correction should not be expected

Until the specification is corrected, foundries should take steps to protect themselves from possible law suits. The first step is to know the specifications that are being required. Know what jobs are being made under A48, and which other jobs require A48 specifications. Do those specifications refer to testing frequency in another section, or do they require the A48 definition?

The next step is to communicate in writing with customers, referring to the option in A48 that allows customer and supplier to agree on testing frequency. In most cases, the customers will be even less aware of the specification difficulty than are foundries. Many will be unwilling to pay for the additional testing that would be required if the strictest interpretation was applied. Therefore, customers are usually quite willing to agree to a testing frequency. Once the frequency is agreed upon, the foundryman then has to concern himself only with producing iron meeting the specification.
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Title Annotation:tensile strength of iron
Author:Lobenhofer, Roy W.
Publication:Modern Casting
Date:Apr 1, 1990
Words:482
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