How was the world’s strongest bolt developed? 14 October 2019

Swedish premium stainless steel fastener company BUMAX has drawn on Nobel Prize winning technology that revolutionised how chemists understand solid matter to develop the world’s strongest bolt.

With the production in central Sweden’s steel belt, premium stainless steel manufacturer BUMAX produces what is now widely known as the strongest fastener in the world. BUMAX® Ultra has proven itself in various highly demanding critical fastener applications around the world – providing optimal safety and reliability where standard fasteners are simply inadequate.

BUMAX® Ultra typically offers a yield strength of over 1350 MPa, which is three times that of standard stainless steel class 70 fasteners (450 MPa) and more than double that of Class 80 fasteners (600 MPa). The fact that BUMAX® Ultra can handle more than twice the load of a standard stainless steel fastener is a game changer for critical fastener applications by providing enhanced solutions that simply were not available a few years ago.

BUMAX capitalised on its own material technology knowledge and that of its premium stainless steel supplier, as well as its advanced manufacturing techniques, to develop the world’s strongest bolt.

BUMAX® Ultra ensures ultra high strength and good corrosion resistance by drawing on Nobel Prize winning quasi-crystalline precipitate technology. Materials Science Professor Dan Shechtman won the 2011 Nobel Prize in Chemistry for his work with quasi-crystals, which has fundamentally altered how chemists conceive of solid matter.

The BUMAX technique uses strain hardening followed by precipitation hardening, which significantly increases the tensile strength of the stainless steel by ensuring the crystal structure reinforces the material. The entire BUMAX® Ultra range of fasteners are made at the BUMAX factory in Åshammar, central Sweden.

The strongest bolt in the world – and it’s stainless
Stainless steel fasteners are often selected for their corrosion resistance properties, however reduced strength has historically been an accepted compromise of using stainless steel rather than carbon steel. BUMAX® Ultra has changed all that by providing ground breaking solutions for highly demanding critical applications.

“BUMAX specialises in the development of high strength stainless fastener solutions – to ensure superior corrosion resistance, while exceeding the mechanical properties offered by carbon steel, standard stainless products and many high alloy fasteners,” explains Örjan Persson, business development director at BUMAX. “Our unique stainless steel fasteners such as BUMAX® Ultra have revolutionised the fastener market by far exceeding carbon steel in terms of tensile strength.”

Application examples for BUMAX® Ultra include:

  • Security lock systems – excellent fatigue properties combined with strength.
  • Aerospace systems – good fatigue, corrosion and strength properties and an alternative to titanium fasteners.
  • High pressure applications – high strength requirement, with space limitations.
  • Pump and valve systems – good fatigue properties when compared to high strength carbon steels.

Since its launch in 2014, the BUMAX® Ultra range has proven that it is capable of exceeding tensile strengths of between 1,500 to 1,700 MPa on various applications, with good corrosion resistance and an operating range of between -50 and 400°C.

BUMAX® Ultra is designed for applications that require ultra-high strength combined with high ductility and fatigue resistance. BUMAX® Ultra applications include security lock systems, aerospace systems, high pressure applications, fueling systems and semiconductor manufacturing equipment – all with excellent results.

BUMAX® Ultra fasteners are increasingly used to replace high strength carbon steel fasteners in critical applications with extreme requirements on strength, ductility and fatigue resistance. The very high strength to weight ratio in combination with BUMAX® Ultra’s good formability and ductility also make it a cost-effective fastener alternative to other lightweight materials such as titanium.

All BUMAX® Ultra fasteners are custom made to meet the requirements of each specific application and can be delivered with different mechanical properties.

“BUMAX® Ultra is an advanced engineering grade and we provide close technical support for customer projects in order to develop the optimal end solution. Even tensile strength exceeding 1,700 MPa is possible with BUMAX® Ultra, together with good corrosion resistance, formability and ductility,” comments Persson.


Application example: Lock manufacturer replaces carbon steel screws with BUMAX® Ultra

A leading European lock and locking system manufacturer originally used a DIN 912, M3 x 4 8.8 carbon steel screw for the critical latch screw. Following breakages that disabled the entire locking mechanism, the manufacturer tested both 10.9 and 12.9 without solving the problem.

The manufacturer then fatigue-tested BUMAX® Ultra, which survived 500,000 strokes without a single breakage – compared with carbon steel screws that only lasted 10,000 strokes. BUMAX® Ultra screws are now a critical lock component that helps avoid lock failure.

Claire Aldridge Deputy Editor t: +44 (0) 1727 743 889

Having spent a decade in the fastener industry experiencing every facet – from steel mills, fastener manufacturers, wholesalers, distributors, as well as machinery builders and plating + coating companies, Claire has developed an in-depth knowledge of all things fasteners.

Alongside visiting numerous companies, exhibitions and conferences around the world, Claire has also interviewed high profile figures – focusing on key topics impacting the sector and making sure readers stay up to date with the latest developments within the industry.