Grade-BD Screws

Kanebridge's Grade-BD Cap Screws Meet All Military Requirements.

Q: What type of steel are Kanebridge’s Grade-BD cap screws made from?
A: Per military requirements, the ASTM A354 Grade BD cap screws are made from medium carbon fine grain alloy steels that conform to the requirements of AISI alloy steels.

All of these materials are fine grained to provide the high levels of strength and toughness, which are required in these critical fasteners. Specific steel grades are chosen not only to meet the alloy steel requirements as listed in ASTM A354, but also to provide the required hardenability. This insures that the final product offers the correct mechanical properties to meet all military specifications.

Q: Do Kanebridge’s Grade-BD cap screws meet the revised ASTM B633 plating specification, including the heat-treating and baking requirements the standard specifies?
A: Yes. The ASTM B633 standard was revised in 2007.

One of the changes concerned the amount of time certain fasteners are baked to reduce the effects of hydrogen embrittlement. Prior to this revision, plated Grade-BD cap screws were required to be baked for at least 4 hours at a temperature of 190°C to 220°C. The new standard calls for these parts to be baked for at least 10 hours at 190°C to 220°C. All of our manufacturers meet this standard.

Q: There are special requirements for how promptly these parts are to be baked after plating. How can I assure my customers your Grade-BD cap screws meet these standards?
A: The requirements you refer to are also delineated in ASTM B633, section 6.5.

This section addresses post-plating treatment to reduce the effects of hydrogen embrittlement, specifically, the time gap between plating and baking. This treatment must be done within 4 hours of the electroplating operation. Rest assured—all of our manufacturers meet this standard.

Q: Are the finished Grade-BD cap screws ultimately tested for hydrogen embrittlement?
A: Yes. The testing performed is in accordance with ASTM F606, called the stress durability test.

Samples of plated fasteners are placed in a static load fixture with a wedge fixture under the head, and the fastener is loaded to 75% of the ultimate tensile strength. The fastener is left with this load for 48 hours. If the assembly has not failed, it is disassembled and examined for any evidence of embrittlement. The test specimens are visually examined under a minimum of 10 times optical magnification.

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Grade-BD Cap Screws, Fine Thread
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Grade-BD Cap Screws, Coarse Thread
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