Researchers at Swerim develop world-unique Swedish standard for measuring argon

Microscopic bubbles can cause gigantic problems. At least if the bubbles consist of the noble gas argon and have been trapped in pressed metal parts. Now a research group headed by Pelle Mellin at the metals research institute Swerim has developed a standardized method that identifies defective metal containing argon bubbles.  This Swedish standard is on its way to gaining international recognition.

If you buy a bicycle helmet or a baby's rattle, you want to be sure that it has been tested and is safe according to a standard. The same applies to many products in industry. Prior to August 2018 there was no Swedish standard for quality assurance of parts manufactured via the PM HIP method (Hot Isostatic Pressing). The material produced using this method is corrosion resistant and can withstand high pressure. It is used, for example, on oil rigs. More specifically as pipes on the seabed.

However, risks arise during manufacturing. The argon that is used as a pressure medium to press the metal into the desired shape can in some cases leak in and remain present in the form of bubbles in the material. Although the bubbles are microscopic, they make the metal brittle, which could prove disastrous if the defective metal objects are not identified and rejected.

Companies that manufacture metal products using the PM HIP method have, of course, relied on quality-control methods for identifying defective products, but there has never been a consistent method that customers could request regardless of supplier. Pelle Mellin, research engineer at the metals research institute Swerim, was tasked with managing a project that aimed for a consistent method and a standard that describes it. For three years he has systematically verified a measurement method and established a common practice which was approved as a standard by SIS, the Swedish Standards Institute, in August 2018.

"It was really satisfying to be able to publish the standard. We were actually first in the world to come up with such a standard," explains Pelle Mellin, who is now also working towards approval of the method by the International Organization for Standardization, ISO.

At ISO the requirements for approval are even higher, so further trials are necessary. Twelve laboratories throughout Europe will perform measurements on the same metal sample, according to Swedish standard. To be approved according to ISO, the measurement results cannot deviate too much between laboratories. 

The research, which has resulted in the Swedish standard for quality assurance of metal products manufactured using the PM HIP method, has been conducted at Swerim in collaboration with Sandvik Materials Technology, Bodycote HIP, Erasteel Kloster, Carpenter Powder Products and SIS Swedish Standards Institute.

Do you want to know more about the Swedish standard for quality assurance of metal? Contact: pelle.mellin@swerim.se