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SBQ STEEL BLOG


Ultrapremium technology born from need to measure steel cleanness

Just like there’s no one medical measurement that can reflect a person’s overall health, there’s no single steel cleanness metric that completely defines the inclusion population in your steel, i.e., how clean your steel is.

That’s why TimkenSteel materials scientists developed a set of cleanness measurements – and the data analysis software to gather them – to provide the full picture of the oxide inclusion population in steel that contribute to early failure in engineered components like gears and bearings.

“It’s always been TimkenSteel’s focus to manufacture and supply steels for the most demanding, highly loaded critical applications,” said Peter Glaws, senior materials scientist at TimkenSteel. “We want to do it in the most cost effective manner. That’s why we developed the cleanest air-melt steel possible and tied it to steel cleanness measurements that are useful for our customers’ design engineers. It’s what defines Ultrapremium technology.”

TimkenSteel’s Ultrapremium process measures oxide inclusions using automated scanning electron microscopy (SEM) with energy-dispersive x-ray spectroscopy (EDS) capability. This allows rapid inspection of a larger area, providing improved understanding of the overall inclusion population. And that means more meaningful cleanness metrics relevant to component design, allowing customers to better determine the probability of critically sized inclusions being located in the high stress regions of the component.

The origin of the analytical tools that resulted in the development of Ultrapremium technology goes back nearly a decade.

“We developed cleanness analysis methods employing the most advanced measurement equipment available,” said Glaws. “Traditional measurement methods are generally incapable of differentiating at higher levels of steel cleanness. You can’t rely on standard non-met or mag particle methods to provide sufficient information. They are just not sensitive enough. Our advanced measurement techniques provide the means to differentiate steels certified to high quality standards. Our analytical systems generate data in a useful form so that gear designers or bearing designers can answer the question: ‘What’s the likelihood of an inclusion related failure in our component?’”

About three years ago, TimkenSteel started working with a company that was having problems with the performance of highly stressed gears. They were using steel that met standard bearing quality specifications, but were still getting early failures.

“We talked to the customer about Ultrapremium technology and their metallurgist was intrigued and excited,” said Glaws. “They gave us three bars to examine.”

Tests showed oxide inclusions were the likely culprit.

Later, the customer used Ultrapremium steel in a test simulating exposure to the harshest service environment conditions for a set number of hours. Historically, these tests resulted in premature failures with competitor materials. With Ultrapremium steel, all the gear sets passed with no failures or signs of fatigue.

It was an easy call for the customer to switch to Ultrapremium steel. Not only was fatigue life longer, but Ultrapremium technology utilizes air-melted steel, which  approaches the cleanness levels of remelt or VAR steels at three to five times less cost.

“People are recognizing that in certain circumstances there’s opportunity to replace remelt with premium air-melt steel,” said Glaws.

Within the last year, TimkenSteel has talked with 20 to 30 more customers about Ultrapremium technology. More samples are on the way to TimkenSteel’s technology center.

“Many of our more discerning customers recognize that as time goes on and they are driven to lightweight or increase power capacity at current size, they need higher quality steels with better steel cleanness,” said Glaws.