Evolution Behavior and Closure Mechanism of Porosity in Large Billet during the Reduction Pretreatment

The reduction pretreatment process was proposed to be applied large billets for the purpose of alleviating center porosities and reducing rolling ratio. This study focused on evolution behavior closure mechanism porosity in a billet during pretreatment. were characterized by ultrasonic scanning 3D reconstruction. results showed that near surface firstly closed began effectively act at deformation 0.16. When amount increased 0.20–0.22, both pore number degree smallest. As exceeded 0.25, gathered billet, which may have caused larger defects. A numerical model established analyze porosity. simulation position with maximum strain moved toward as increased. At where 0.20, would readily occur center, almost twice much strain. upper lower surfaces compressed thickness direction. two ends not stretched index indicated penetrated into accelerate cross-sectional area gradually decreased increase hydrostatic integration, integration could used assess process. Both proved effective role alleviation