Simulation of the Kinematic Condition of Radial Shear Rolling and Estimation of Its Influence on a Titanium Billet Microstructure

Abstract

The finite element method (FEM) computer simulation of the three-high radial shear rolling of Ti-6Al-4V alloy round billets was conducted using QForm software. The simulation was performed for the MISIS-100T rolling mill’s three passes according to the following rolling route: 76 mm (the initial billet diameter) →65 mm→55 mm→48 mm (the final billet diameter). The change in the total velocity values for the points on the radius of the 48 mm diameter billet was estimated while passing the rolls’ draft. The relative increase in the accumulated strain was estimated for the same points. Then, experimental shear rolling was performed. Grain sizes of the α- and β-phases were estimated in the cross section of the final billet at the stationary stage of rolling. The grain size distribution histograms for different phases were plotted. An area was found in the billet’s cross section in which the trend of change in the total velocity of the points changed. This area represented a neutral layer between the slowing peripheral segments of the billet and the accelerating central segments of the billet. Inside this neutral layer, the limits of the cylindrical surface radius value were estimated. Experimental radial shear rolling was performed to compare the experimental rolling results (the billet microstructure investigation) with the computer simulation results. The computer simulation obtained two estimations of the radius limits: 8–16 mm (based on the analysis of the total velocity change) and 12–16 mm (based on the accumulated strain’s relative increment change). The experimental rolling obtained two more estimations of the radius limits: 8.4–19.5 mm and 11.3–19.7 mm—based on the results of the microstructure investigation. It was confirmed that varying the kinematic and deformation parameters of radial shear rolling allows regulation of the thickness of the peripheral fine-grain layer and the diameter of the central coarse-grain layer of the rolled billets.

Research of Three-High Screw Rolling of Aluminum Billets with Copper Inserts at Different Rolls Feed Angles

“…It was shown in [6,12,30] that the accumulated strain at three high screw rolling follows the same pattern (independently from the rolling regimes and the billet material): a monotonous increase from the billet center towards the billet surface. Considering the theoretical background to the strain condition when three-high screw rolling and three-high RSR [4,5], it appears that an increase in the rolls feed angle should increase the accumulated strain values in the central region of the billet or decrease the drop in the accumulated strain values between the billet surface and the billet center, as suggested in [1,4].…”

“…A number of materials are rolled at the three-high RSR; in this case the grain size decreases significantly, and the range of properties increases. These changes are due to the kinematic condition of the material helical flow [6]. The effects of the three-high RSR on the microstructure and properties formation were investigated for the following materials: titanium alloys [7][8][9][10], copper alloys [11], magnesium alloys [12][13][14][15], nickel alloys [16], zirconium alloys [17], and aluminum alloys [18,19].…”

“…Thirdly, the qualitative and quantitative trends in the changes in the axial and peripheral microstructure zones in the billet as well as qualitative microstructure variation along the radius of T11302 steel billets at the three-high RSR [5]. Finally, the observed relationship between the dimensions of the peripheral fine-grain zone and the coarse grain axial zone (which are formed due to kinematic features of the three-high RSR), as well as the observed relationship between the grain size value and the accumulated strain value at the three-high RSR of AISI 321 steel billets [6]. Considering all these four aspects, it is important to continue further research on three-high screw rolling at different feed angles of rolls.…”

Numerical Simulation as a Tool for the Study, Development, and Optimization of Rolling Processes: A Review

“…Tube piercing, also known as skew rolling piercing, is a hot rolling process used in the manufacture of seamless tubes. In this process, a cylindrical billet heated to over 70% of the melting temperature of the material is placed between two rolls, and a piercing plug begins to pierce and stretch the billet along its entire length [118]. Simultaneously, two large disks, referred to as Dieschers, govern the geometry of the pierced billet to enhance geometrical accuracy [119].…”