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Cooperation furthers innovative brazing solutions

What happens when two companies decide to work together and share findings and innovations? SWEP and Höganäs know: New and improved products that can benefit all kinds of industries!

The 11th International Conference on Brazing, High Temperature Brazing and Diffusion Bonding brought together the professional world of joining technology in Aachen, from June 7 to 9, 2016. Present at the conference were Ulrika Persson from Höganäs and Niclas Bornegård from SWEP. Their joint paper, called 'New nickel based brazing alloy suitable for very corrosive environments', was awarded a prize for best presentation. The paper differed from many of the other papers which were more academic in nature. Instead, the SWEP/Höganäs paper describes a real case, presenting the development process and highlighting the importance of cooperation and openness to further innovative ideas.

SWEP has been working with Höganäs the last ten years or so, and together they have developed a number of innovative brazing solutions to meet customer needs. SWEP is a company at the forefront of brazed plate heat exchanger (BPHE) technology, offering a wide range of products that allows you to optimize the use of energy, material, and space in your heating and cooling systems. Höganäs was established in 1797 as a coal mining company, but is today a modern, forward-thinking enterprise with a focus on metal powders for a variety of industries, among them brazed plate heat exchangers and the automotive industry. Both companies are based in southwestern Sweden, but cater to a global market.

The case presented came from one of SWEP’s customers. It dealt with a new application for plate heat exchangers used in cooling units that were subjected to a very aggressive coolant. That meant that both base material and brazing alloy needed to have very high corrosion resistance to the coolant. High alloyed austenitic stainless steel was early identified as the preferred base material, meeting the required properties. The only existing braze material with good enough corrosion resistance was BrazeLet® Ni613, but what looked good on paper could not handle reality. When testing the alloy, it was recognized that its melting range was not compatible with the base material used.

The requirements were tough, but clear. High alloyed austenitic stainless steel may form intermetallic phases during cooling and to avoid this, the material needs a special heat treatment. The melting range of the Ni613 was too low. Secondly, it was desired that the brazing alloy be as close to the chemistry of the base material as possible in order to minimize element migration between the two. Thirdly, Silicon, Boron and Phosphorus should be kept low since they consume Chromium. After listing these requirements, everyone involved realized that they needed to develop a new brazing alloy.

Together, SWEP and Höganäs set to work, in close cooperation with SWEP’s customer and the provider of the base material. After only six months, the first sample was presented. “Since the requirements were clear, we simply kept testing and developing the alloy until all the demands had been fulfilled”, says Ulrika Persson at Höganäs. “The biggest challenge was the temperature”. In total 34 different compositions were investigated during the development work. “We decided early on to cooperate and present our findings to each other openly”, says Niclas Bornegård from SWEP. “We see it as one plus one equals three – we can learn from each other and that benefits both of our companies”.

 

Within a year, they were done. The new material has the composition Ni-29Cr-8Mo-xFe-ySi and is patent pending. It has a solidus temperature around 1150⁰C (2100⁰F) and is suitable for use in applications where high alloyed austenitic stainless steels are needed. The strength is equal to Ni613 when brazed together with 304L stainless steel base material and increased by around 37% when brazed together with SMO254 compared to 304L.

Although it is possible to customize the base material and corresponding alloy for any application, the financial situation has to allow for it and both Ulrika and Niclas take the business case into consideration when developing new materials. “Investments can be a tough burden within this field, but one alloy can be used in a variety of applications”, says Ulrika. “The cost for development can then be spread over several business cases.” According to Ulrika and Niclas, the development of new brazing alloys has just begun and they are looking forward to further cooperation. The two companies’ business ideas work well together. Höganäs’ ambition to inspire industry to make more with less meets SWEP’s aspiration to challenge efficiency and make a difference. Both companies also believe in working close to the customer and finding solutions to specific needs. “We have a cooperation built on trust”, says Niclas. “And I am looking forward to writing manymore papers together with Höganäs”.

If you would like to read more about our BPHE technology, please click here.