CSG Introduces BUMAX® DX 129 for the Most Demanding Fastener Applications
The Case for Stainless Fasteners
There are many applications where engineers struggle to find fastener products that can combine high mechanical strength and corrosion resistance. Design engineers often turn to high-tensile carbon steel bolts, coupled with a secondary external coating
to provide some corrosion resistance. While this may be the most commonly used option, it is by no means the most reliable or cost-effective option, especially for high-performance or safety-critical applications or applications where the economic cost of failure and/or maintenance is significant.
The use of high-tensile carbon steel bolts (e.g., TS > 145 ksi & YS > 130 ksi) is not without its challenges. If not done correctly, the manufacture of such high-strength carbon steel fasteners makes them prone to hydrogen embrittlement, which can leave them susceptible to sudden brittle failure during operation. The choice of the many available coating options, with varying capabilities and performance, will also be a key performance factor.
Unlike stainless steel materials, these coatings can be damaged during installation or operation, further increasing the risk of corrosion. The added supply chain and quality management issues introduced as a result of combining a fastener and coating product, usually the responsibility of two different suppliers, add to the complexity and cost of this solution.
The other traditional option is to upgrade to nickel alloys, which are almost always manufactured to order and can be hard to source. These can have long lead times and can become very expensive when used for higher-volume requirements. These cost and risk factors have created an intermediate gap in the market. BUMAX has engineered a solution that will solve many of these issues for a variety of applications.
The BUMAX DX 129 Product Grade
BUMAX® DX 129 was explicitly designed for performance —and safety-critical applications where a combination of high strength and corrosion resistance is required.
Duplex stainless-steel materials are austenitic-ferritic, a two-phase microstructure containing ferrite and austenite. The mix of ferritic and austenitic phases is roughly 50/50, which optimizes corrosion resistance and provides the necessary mechanical properties. Duplex stainless grades significantly outperform more traditionally used materials such as A4/316 or B8M.
BUMAX DX 129 provides significant advantages in many applications. They deliver very high strength, and excellent ductility. They’re highly corrosion-resistant and do not suffer risk of hydrogen embrittlement, as a result of any manufacturing process they undergo. They offer the potential to downsize fastener dimensions, as well as equipment size and weight, if considered early enough in the design process. There are also substantial sustainability benefits; they reduce ongoing maintenance, increase longevity, and are highly recyclable at the end of product life.
Market Application Examples
BUMAX DX 129 has rapidly grown a significant base of loyal customers who benefit from the performance and reliability of this fastener material grade.
Defense
A military contractor was designing mission-critical equipment for an armored vehicle. The equipment, attached to the exterior of the vehicle, was subject to harsh operational conditions. This customer had previously limited their use of very high tensile carbon steel fastener specifications such as 12.9 screws (which have 1220 MPa minimum tensile strength), because of prior experience with sudden and unexpected failure due to suspected hydrogen embrittlement.
An additional complication was that the parts had to be coated to reduce reflective qualities. Coatings and plating processes can also potentially contribute to the risk of hydrogen embrittlement if not selected and applied correctly.
10.9 carbon steel bolts were considered but as these were weaker (145,000 PSI compared to the 12.9’s 175,00 PSI strength.) these would leave very little safety margin in the design, unless increasing the diameter of the bolts.
The contractor’s engineers had not initially considered a stainless steel option in this application on the assumption that the strength requirements could not be met. Further research led engineers to discover BUMAX high strength stainless steel fasteners and it’s DX 129 product grade.
Following several months of evaluation, BUMAX DX 129 was successfully implemented for that application and has since been adopted on further critical applications by several of the company’s engineering teams.
OEM Manufacturers
Another customer, an OEM of industrial process equipment, was experiencing ongoing issues with unexpected failures of coated high-tensile carbon steel fasteners. They were also facing significant challenges managing the quality of the coating application, which was frequently found to be out of specification and thought to be a contributing factor in the fastener failures.
This presented knock-on challenges with their product reliability. The company was concerned about the significant time and resources they were investing in managing these problems and providing service; the issue was becoming a risk to their brand credibility.
Through online research, they discovered BUMAX DX 129. They purchased a small quantity of fasteners for initial testing purposes. The results of these in-house tests demonstrated that mechanical performance was an improvement compared to their existing fasteners, while a duplex stainless steel would be far superior to the corrosion performance that could be offered by any secondary coating.
The customer also conducted a cost-impact analysis, which showed that DX 129 fasteners would result in an approx. 30% increase over their current fasteners. For this application, the total cost of all fasteners used within the unit was a relatively small portion of the overall production cost of the equipment, making DX 129 a compelling option to eliminate the ongoing challenges they were facing in this situation.
The strength and durability of DX 129 products makes them ideal for applications in some of the harshest conditions in the world where other fasteners can’t perform. The BUMAX® DX (Duplex) 129 has been used in marine environments, military, aerospace, automotive, manufacturing, construction, and many other applications. DX 129 is increasingly being used within industries where the cost of fastener failure can greatly outweigh the actual cost of the fasteners themselves.
BUMAX DX 129 is available from stock in socket head cap screws (ISO 4762) and fully threaded hex head screws (ISO 4017). DX 129 can also be manufactured to order in a variety of fastener types, from diameters at 7/32 inches to 3/8 inches (M6 to M20).
The BUMAX DX 129 product grade is a leading-edge innovation that combines high strength, ductility, and corrosion resistance. Component Solutions Group (CSG) is the leading BUMAX supplier, offering access to a reliable, high-performance, and cost-effective solution for the most demanding fastening applications.
To learn more about BUMAX products and how they can support your needs, get in touch with a BUMAX specialist today.
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