Effect of cold swaging and heat treatment on properties of the P/M 91W-6Ni-3Co heavy alloy

Abstract

This paper describes the effects of rotary swaging and heat treatment under different conditions on mechanical properties and microstructure of the P/M 91W-6Ni-3Co alloy. The investigation was performed on cold rotary swaging rods with 10, 20 and 25% reduction in area, heat treated at 11300C for 90min under different cooling conditions and strain-aged at temperatures from 300 to 8000C for 60, 180 and 360min. Tensile and toughness testing of rotary swaging rods showed that increase in the reduction resulted in intensive strengthening and toughness lowering. The results of tensile and toughness testing of heat treated rods have shown a decrease in strength, ductility and partly toughness in comparison with the mechanical properties of swaged alloys. The results of strain aged rods demonstrate that, for this cold rotary swaging alloy, there is a temperature range from 500 to 6000C for 60min in which the maximum ultimate strength and hardness may be attained

Effect of Cold Swaging on the Mechanical and Microstructure Characteristics of Tungsten Heavy Alloy

“…On the other hand, ductility and impact resistance were deeply decreased by about 75% and 53% respectively, by also, the application of 50% area reduction by swaging. It was shown by M. Nikačević et al [8,9] that, During rotary swaging, strength intensively increases, while ductility and toughness were found to be quite reduced compared to the init ial sintered condition. A high gradient of hardness in the rods cross section can be noticed as well.…”

“…Moreover, a clearly visible grain deformation can be recognized particularly at the structures subjected to heavy percentages of deformat ion under the swaging process. B. Katavić [8,9] reported that, there are no significant changes in the W phase grain size or in the volume fract ion of W and matrix phases as an effect of plastic deformat ion after rotary swaging while the mean distance between W-grains was found to be reduced. While the longitudinal cross -section Microstructure of the adopted heavy tungsten alloy specimens obtained under different values of area reductions by rotary swaging was shown in Fig.5.…”

“…The measurement of density of the five different specimens of the same alloy produced under different area reduction percentages (10, 20, 30, 40, and 50%) using rotary swaging showed that, a slight increase of relative density can be reported between 10 and 20% of area reductions, while with higher reductions of area did not reveal any significant change of relative density, as shown in Fig-2. B. Katavić [8], reported that, rotary swaging has very limited effect on alloy density particularly in tungsten heavy alloys. Fig-3, illustrates the evolution of the mechanical properties of the adopted heavy tungsten alloy (89.97W -7Ni-3Fe-0.03Y2O3 %wt) with the application of different reductions of cross sectional area using rotary swaging technique.…”

Some features of sintering of tungsten powders

“…Tungsten and its alloys because of their unique characteristics have wide application in many sectors of the industrial production [1][2][3]. One of the topical applications of tungsten materials is the thermonuclear energy, where tungsten can be used for protection against plasma of parts of the first wall and the diverter [4,5], because of its operational strength to 20 times higher than the resistance of iron, copper, beryllium and 10 times-molybdenum.…”

Effect of heat treatment on microstructure and mechanical properties of hot-hydrostatically extruded 93W–4.9Ni–2.1Fe alloy

“…In the past several decades, many preparation technologies of tungsten heavy alloys have been reported, such as spark plasma sintering and microwave sintering [4][5][6], cold rolling [7][8][9], highpressure torsion [10][11][12], rotary swaging [13][14][15][16][17][18][19][20][21][22][23], hot extrusion [24][25][26], hydrostatic extrusion [27][28][29][30]. But, many publications up to the present have shown that hydrostatic extrusion is one of the most effective processes for deformation strengthening technique for the consolidation of powder materials, especially difficult-to-deform materials, such as WHAs including W-Ni-Fe [27][28][29][30], and W-Cu series alloys [31][32].…”