The influence of radial shear rolling on the structure and properties of 58Ni-Cr-Mo-B-Al-Cu superalloy

Abstract

The work is devoted to a study of the microstructure and microhardness of the heat-resistant nickel-based superalloy 58Ni-Cr-Mo-B-Al-Cu after radial-shear rolling. The radial-shear rolling was carried out at a temperature of 925°С in three stages. It was found that the grain size of γ-phase after all rolling stages decreased in the radial direction from the center to the periphery from 62 ± 2 to 2.5 ± 0.2 µm. At the third rolling stage, the grains size was reduced twice in the billet center in a comparison to the initial state. At the same time, individual grains with a size of 100 μm in the billet surface are observed, and grains with a size of 1±0.1 μm are present at the periphery. The microhardness changes in inverse proportion to the grain size, the values increase in the radius direction. The maximum microhardness value is achieved in the peripheral part of the sample and is equal to 5.4 ± 0.6 GPa. According to the EBSD analysis, there is no texture at the billet periphery, but at the middle of the radius there is a two-component axial texture of the <001> + <111> type along the billet axis. The billet center is characterized by the presence of a more pronounced two-component axial texture of the <001> + <111> type along the billet axis. The obtained results indicate the possibility of the gradient structure formation by radial-shear rolling in the heat-resistant nickelbased superalloy 58Ni-Cr-Mo-B-Al-Cu with the initial coarse-grained structure.

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

“…This trend was a monotonous increase in hardness from the center of the rolled billet towards its surface. The same trend was observed for tube steel three-high rolling at a 20-degrees rolls feed angle[31], nickel alloy at an 18-degrees rolls feed angle[32], and magnesium alloy at an 18-degrees rolls feed angle[33]. That is, all these investigations were conducted under conditions of the three-high RSR[31][32][33].…”

“…Hence, there could be an overlap of temperature and stress-strain influences and this is an issue to be investigated in further research. Nevertheless, the hardness change patterns observed as a result of the present research have been identified for other screw rolling temperature and deformation regimes and for other materials, such as titanium alloy [30], steels [29,31], nickel alloy [32] and magnesium alloy [33]. Microstructure twist, as illustrated in Figure 10b,c, was identified for the three-high screw rolling of commercial pure aluminum billet at completely different temperatures from the current study temperature and deformation regimes [36], three-high screw rolling of AISI 1020 steel billet [37], and of AISI 321 steel billet [36].…”

Superplastic forming of EK61 nickel-based superalloy with ultrafine-grained structure

“…The deformation-heat treatment was carried out to obtain an ultrafine-grained structure of a duplex type in the EK61 superalloy. Such processing was performed using the wellknown [7,9,18,30] method of multiple isothermal forging developed at IMSP RAS [7,18].…”

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

“…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%.…”