Forging Method for Consolidating Loose Structure in Steel Ingot with V Shaped Dies

The moire techinque is used to measure the two and three dimentional deformation of round billets in forging with 135°V dies. Each billet is made by piling up 0.75 mm thin white plasticine sheets painted with black ink. From the observation of moire fringes an Octagonal Forging Method (OFM), characterized by sequential billet rotation through 0° 90° 135° 225° in the cross section, is proposed to consolidate the loose structure in the wide area of ingot center. Strain distributions for various cross sections in a billet are observed by the moire method. No deformation takes place in the center of the billet near the die edges. A plasticine ingot is forged according to the OFM by axially shifting the ingot by the full die-width or 1/4 of the width. A comparison of axial strain distribution is made between two ingots thus obtained. A 3%Cr steel shaft by the full die-width shifting method with the OFM has loose structure remaining at the center ; the locations of the loose structure correspond to the small axial strain regions. Loose structure in another 3%Cr ingot is consolidated by the 1/4 die-width shifiting method with OFM.