The Effect of Process Variables on the Structure and Properties of ODS, γ'-Hardened Nickel-Base Superalloys

Directional recrystallisation processing: a review

“…Both Baker et al [36,37] and Zhang et al [38,41,44] have found that in particle-free metals or alloys, there is a lower limit to the annealing temperature for columnar grain formation through directional secondary Si 1373 NS 3-30 [13] Ni-based superalloy PWA1123 NS NS NS [14] Fe-3wt-%Si 1323-1623 320-550 increased with increasing T 19 [15] Ni-base superalloy TMO-2 1563 25 50-100 [16] Ni-base superalloy MA6000 1123-1373 NS NS [17] Ni-base superalloy MA6000 1373-1573 NS 48-600 [18] Ni-base superalloy APK-6 1493 NS 2.0-20.0 [19] Ni-base superalloy MA6000 and MA760 1523 NS 2-200 K min −1 (heating rate) [20] Ni-base superalloy MA6000 1443 25 38 [21] Fe-based Superalloy MA957 1673 NS 20-75 [22] Ni-base superalloy MA6000 1623 40 38 [23] Ni-base superalloy MA6000 1223-1503 NS 15-400 [24] Ni-based superalloy PM3030 1503 100 NS [25] Ni-base superalloy MA6000 and MA760 1573 40 38 [26] Fe-based Superalloy MA 956 and MA957 1533-1613 50-140 24-75 [27] Ni-base superalloy MA6000 and MA760 1448 NS 38 [28] Ni-base superalloy MA760 and iron-based superalloy MA 956 ∼1523 NS 48-600 [29] Ni-base superalloy MA6000 1223-1273 NS 10-100 [30] Ni-base superalloy SRR99 ∼1533 NS 5 [31] Ni-base superalloy MA6000 1573 NS 38 [32] N i 3 Al 1698 NS 25-100 [33] Ni-base superalloy APK-6 1493 NS NS [34] TiAl-based alloy 1553-1593 NS 1.62 and 4.02 K min −1 (heating rate) [35] Cu 643-743 70-270 2-600 [36] Ni 1273 ∼1000 and 50 2-100 [37] Ni 1073-1273 ∼1000 and 50 2-100 [38] Iron 973-1123 ∼200 3.6-90 [39] Iron 1123-1473 ∼200 and 400 3.6-90 [40] Iron 1123 ∼200 0.36-90 [41] Iron 948-1173 ∼200 1.08-108 …”

“…The lower processing temperatures required for directional recrystallisation allow easier processing of high melting point materials such as tungsten [5,6]; . It is likely that minimal solute redistribution will occur, allowing single crystals or columnar grain structures to be produced from non-castable alloys, such as advanced nickel-based superalloys [7][8][9][10][11]13,[15][16][17][18][19][20][23][24][25][27][28][29][30][31]43,46,50,51], and avoiding the homogenisation anneals that are required to remove the interdendritic segregation that occurs in single crystals of nickel-based superalloys grown by directional solidification, again potentially producing cost savings; . Complex net-shaped (but not re-entrant geometry) structures can, in principle, be processed, producing cost savings compared to directional solidification by avoiding the need for costly moulds and cores [13,66,75], see, for example, the hollow turbine blade with cooling holes shown in Figure 2 [75]; .…”

An EBSP study of directionally recrystallized cold-rolled nickel

“…Directional recrystallization can be used to produce columnar grain structures that have grain boundaries roughly parallel to the direction of hot zone movement [1][2][3][4][5][6][7][8][9][10][11]. Besides this effect on the grain shape, marked changes in texture also occur during directional recrystallization.…”

“…A "stopper", a length of specimen run at a lower temperature, was used to differentiate two differently processed regions of the specimen [8]. Since long strips of nickel (>250 mm) were used, five or six different velocities could be examined per strip.…”

“…By using different rolling and annealing conditions to produce different initial textures followed by directional recrystallization, Chin [6] was able to produce a range of orientated superalloy sheets, consisting of either single crystals or elongated grains with {1 1 2}<1 11>, {0 0 1}<1 1 0> or {1 1 0}<1 1 2> textures. A {1 1 0}<1 1 2> texture has also been produced by directional recrystallization in a number of oxide-dispersion-strengthened nickel-based superalloys, such as PM3030, MA760 and MA6000 [6][7][8][9]. In contrast, Lejcek and Sima [11] used directional secondary recrystallization to generate either columnar grains or single crystals that had a 19 • -orientation relationship with the cubegrains exhibiting cube or {1 2 4}<2 11> orientations (see reference [13] for a pole figure from the as-received nickel).…”