Formation of a Gradient Structure in Austenitic Stainless Steel AISI 321 by Radial-Shear Rolling

Abstract

One of ways to increase the strength of a structural material is to grind its microstructure to an ultra-fine-grained state. But with the simultaneous increase in strength properties in ultrafine materials, there is an inevitable decrease in its plastic properties. The use of metal materials with a gradient structure is an effective way to solve the problem of increasing the plasticity of metal products in general. This work is devoted to the study of the possibility of a gradient structure forming in austenitic stainless steel AISI-321 using radial-shear rolling. The results of the studies showed that the UFG-structure extends in the bar from its surface to a depth of at least a quarter of the radius of the bar. The transition zone is in the region between 0.5 R and 0.25 R of the bar section. Anything deeper is rolling texture. Due to the structural heterogeneity of the cross-section of the bar, there is a smooth drop in the micro-hardness of the central zone of the bar by 10.2 %. All this testifies to the gradient character of the structure formed in bars of AISI-321 steel deformed on the radial-shear rolling mill.

Effect of radial-shear rolling on particle's morphology and mechanical properties of AA7075 alloy

“…As reported in [30], even after SPD, such as ECAP, the maximum plasticity obtained for the AA7075 alloy slightly exceeds 10%, while the strength values are very close. The results obtained in this article for AA7075 alloy subjected to RSR process are in good agreement with the concept of development of gradient grain structure during RSR described earlier in the studies of authors of this work [29,31] and other researchers [21,32] and its influence on the mechanical properties characterised by both high strength and ductility.…”

“…The advantages of the gradient structure of materials are detailed in the works of Chao Xin et al [15], Xiao Lei Wu et al [16], Prokofiev [17], and others. Earlier, different research groups have carried out the studies of influence of RSR on microstructure and properties formation of steel, some aluminium, titanium, and copper alloys [18][19][20][21], where it had been shown the positive effect of RSR and the possibility to increase in mechanical and functional properties. The obtaining of the structure providing the saving of ductility at the increase in strength, and the possibility to manage the process of deformation evolution and to deform the low-ductile grades of steels and alloys can be ascribed to unique possibilities of RSR method [19,22,23].…”

Obtaining an Equiaxed Ultrafine-Grained State of the Longlength Bulk Zirconium Alloy Bars by Extralarge Shear Deformations with a Vortex Metal Flow

“…TEM study according to the position of the transparent part of the sample corresponds to an area remote from the center by about 5 mm or 1.5 mm from the edge. The study is fully consistent with the EBSD data from this and adjacent areas, as well as with data from similar studies of the peripheral region in bars obtained by radial shear rolling [ 16 , 24 , 28 , 30 ] and other SPD methods [ 7 , 8 , 9 ]. Here, it is important to note the equiaxed nature of grains and high-angle boundaries, as evidenced by electron diffraction in the corner of the image.…”

“…The radial shear rolling method has become in recent years increasingly popular for significant structure refinement of steel [ 16 , 19 , 20 , 21 , 22 , 23 , 24 ], titanium [ 25 , 26 ], aluminum and magnesium alloys [ 27 , 28 , 29 ], copper [ 16 ], zirconium [ 30 ], and other alloys [ 31 , 32 , 33 , 34 , 35 ]. However, in many cases, the deformation on the one setup is used, and the total deformation by diameter does not exceed ε = 50%.…”

Numerical simulation of workpiece temperature field during radial shear rolling of biomedical Co-Cr-Mo alloy

“…The radial shear rolling (RSR) method is implemented using universal, low-energy-intensive, and compact equipment [12,13]. This method is widely used for industrial production of bars in wide dimensional range from various non-ferrous and ferrous metals [14][15][16]. Moreover, as previous studies have shown, the RSR method contributes to an increase in the plasticity of the material, while the strength level remains the same or above the level compared to other industrial metal forming methods [17][18][19].…”