TimkenSteel’s Ultrapremium™ and Endurance Steels: Combining cleanness, strength and toughness for affordable power densification

Increased power density in aerospace mechanical power transmission components means greater durability – allowing existing designs to achieve greater capacity, or reduced size and mass for lightweighting. TimkenSteel’s Ultrapremium™ certified air-melt technology and Endurance family of ultra-high-strength, high-toughness steels provide affordable solutions for critical, power-dense aerospace components. Ultrapremium steels combine advanced electric arc melting, vacuum ladle refining and teeming practices with advanced automated scanning electron microscope (SEM)-based steel cleanness evaluation. The result is affordable, certified ultra-clean steels on par with re-melted steel with cleanness metrics that are relevant to component design life. In addition, three new steels in our Endurance family provide yield strengths ranging from 175-210 KSI, ultimate tensile strengths ranging from 230-250 KSI, and Charpy impact energies ranging from 35 to 50 ft.-lbs., allowing these grades to provide longer life, more power and/or lighter weight.

Our measurement techniques compare automated SEM-assessed cleanness data between Ultrapremium and vacuum arc re-melted steels to illustrate equivalence, and we illustrate how Ultrapremium certification data can be used to assess and estimate fatigue risks using the TimkenSteel virtual component fatigue model. For Endurance grades, we compare their strength, fatigue and toughness properties to a range of common case-carburized gear steel properties. This analysis illustrates the potential to gain 45 percent more horsepower for an existing gear set, or to achieve the same horsepower with a 30 percent lighter gear set.