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SBQ STEEL BLOG


Encouraging a new industry standard

For decades, the steel industry has relied on reduction ratio as a common measure of center soundness in steel bars, or the shrinkage porosity left over from casting. This ratio is an easy measurement between the as-cast cross-sectional area and the final bar cross-sectional area. However, the dated reduction ratio standards of 6:1 for rolled only and 3:1 for forged bar don't really indicate what's happening in the center of the bar.

 

With more advanced tools like ultrasonic testing, we can provide a true measure of the factor we actually need to determine center soundness - the porosity inside the bar.

 

TimkenSteel's forged-rolled process for large bars combines forging and rolling in a series to take advantage of both deformation processes. We take the initial heavy reduction hits from forging, which drives deformation to the center to heal the porosity, and we roll the forged blooms to achieve the desired shape and size control. With a full feedback loop including computer simulation and plant trials, we've achieved large bars with confirmed center soundness and reduction ratios at less than 3:1.

 

See why we believe the industry standard should move away from reduction ratio and toward ultrasonic testing to guarantee a bar product's level of soundness.