In December 2017, SAE released an updated and much-needed version of AMS 4928. Before we dig into some major changes in AMS 4928W, let’s take a look at where AMS 4928V left off.
AMS 4928 is a specification for titanium bar, wire, forgings, flash-welded rings, and drawn shapes. AMS 4928 is specific to the 6AL-4V alloy.
AMS 4928V covered products up to 6” in diameter or least distance between parallel sides. However, it is commonly requested for products larger than 6” to be certified to AMS 4928. Since larger sizes were not specifically covered in the specification, AMS 4928V left it up to the purchaser and producer to determine what mechanical requirements could be satisfied for any products outside of the range identified in the specification. Usually manufacturers interpreted this as either (1) product manufactured in a size outside of the range of AMS 4928V would be manufactured to meet the properties of the largest size that is covered, or (2) since there are no specific requirements for products outside of the range of the specification, test results would be for information only, and not cause for rejection.
AMS 4928W recognizes that purchasers and end users are looking for assurances of what mechanical properties can be achieved in larger section sizes, by extending the coverage to 10” in diameter or least distance between parallel sides. This allows titanium AMS 4928W products in this extended range to be certified without a “for information only” caveat; we now have firm requirements. For products larger than 10” diameter or least distance between parallel sides, the spec still does mandate the purchaser and producer to agree on the properties.
The new revision of AMS 4928 also brings about changes in reporting and identification of products. Now, when a product is purchased outside of the range of AMS 4928W, the report (or some type of certification) must include a statement certifying the material as “AMS 4928W(EXC)”, and list the exceptions to the specification. This requirement also applies when any technical requirement is waived. Additionally, the material must then be marked with “AMS 4928W(EXC)”.
Another change noted in AMS 4928W relates to the surface contamination examination. Where AMS 4928V required surface contamination to be examined at a 100X minimum magnification, AMS 4928W requires 400X.
Some customers are wondering, if I have a certification to AMS 4928V, is it going to meet AMS 4928W? The answer is maybe. You must go back to the certification authority (the manufacturer who issues the certification) for this determination to be made. If you have purchased from a party other than the manufacturer, the request must run through the party you purchased from, and up the chain. Also, note that additional testing may be required if the surface contamination wasn’t previously examined at a magnification as high as AMS 4928W requires.
Note: Performance Titanium Group is a raw material distributor. PTG does not provide engineering or metallurgical advice. Do not use this information to make engineering or metallurgical decisions. This information is subject to change, without notification. PTG is not liable for any damages related to the use of the information provided herein. The entire risk is assumed by you, the user.
This posting is not inclusive of all amendments to the specification. To catch up on all of the changes in AMS 4928W and determine how they affect your organization, be sure to purchase a copy at http://standards.sae.org/ams4928w/.