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SBQ STEEL BLOG


Forged-Rolled Process Advances Sound Center Capability Beyond Reduction Ratio

TimkenSteel recently invested in a forge press that created a new forged-rolled process path to produce large bars (greater than 9 inches in diameter) with sound centers. 

Why the focus on sound centers?

Remnant porosity from steel solidification can have a detrimental effect on properties.  To minimize these effects, we control the casting process variables to minimize porosity. Then we apply multiple types of hot deformation to help eliminate porosity and produce our final product. Forging heals the remnant porosity at the center of the bar while rolling contours the surface to meet strict size tolerances.

Historically, customers have used reduction ratio (the ratio between the as-cast and final cross-sectional areas) as a proxy for center soundness despite the fact that reduction ratio only accounts for the geometric shape change, not the center condition. Using advanced modeling tools, TimkenSteel can focus on optimizing center soundness without the traditional constraints of reduction ratio. These process modeling tools are validated against actual ultrasonic testing results and used to optimize the forged-rolled process path.

The forged-rolled process path contains the best of both worlds – center consolidation of forging plus the size control of rolling.  It allows TimkenSteel to produce sound, large bar product at geometric reduction ratios lower than those historically possible in rolled-only product.

For more information, see our presentation from Forge Fair 2015, or read our paper, which we presented this week at the Association for Iron & Steel Technology’s Long and Forged Products Conference in Vail, Colo. You also can watch the forged-rolled process in action on YouTube.

Forge-rolled 

Patrick Anderson is Manager of the Advanced Modeling group for TimkenSteel in the Advanced Steel Technology department.  He received his BS and MS degrees in Metallurgical and Materials Engineering from the Colorado School of Mines (CSM) in 2003 and 2006. Patrick joined TimkenSteel in 2006 and has since worked on projects related to alloy development and advanced computer modeling of metallurgical processes.