Precipitation Hardening in 350 Grade Maraging Steel

A Review on Nano-Scale Precipitation in Steels

“…Finally, the paper is wrapped up with the challenges and the future directions of nano-scale precipitate strengthened steels. [28] (Fe,Mn) 3 AlC 0.38 [6], (Fe,Mn) 3 AlC 0.51 [6] M 2 C carbides Hexagonal [18] (Mo,Cr) 2 C [17]; (Mo,Cr,V) 2 C [30] Co-located with Cu on lath boundaries and dislocations [17] Rod (coherent) [17]; Irregular (incoherent) [17] Ni 3 Ti Hexagonal (DO 24 ) [36,37] → L1 2 [37] → FCC [37] (Ni,Fe,Co) 3 (Ti, Mo) [14] Homogeneously throughout matrix, heterogeneous nucleation on interphases, dislocations and grain boundaries [36] Disc and rod [14,36] NiAl B2 [3,15] Ni, Al, Mn, Fe, Cu [15,35]; Ni, Al, Fe, Mn [2]; Ni(Al,Fe) [3]; Ni, Al, Fe, Cr, Mo [38] Co-located with Cu [15]; Mostly homogeneously distributed in matrix and some elongated particles on dislocations [3] Spherical [2,3] [7] Cu and (Ti,Mo)C Fe-1.53Mn-1.17Cu-0.34Si-0.21Mo-0.09Ti-0.04Al-0.07C 732 13 [16] * Monzen et al [21] argued that the B2 to 9R transformation depends on the surrounding temperature. At 500 • C, the transformation occurs at 12 nm instead of 4 nm.…”

“…A compilation of (a) yield strength increment and (b) ductility change against precipitate number density of various precipitate strengthened steels. TiC [40] Ni3Ti [14] Cu + NiAl -4%Ni [1] Cu + NiAl -2.5%Ni [1] NiAl -3%Mn [2] NiAl -no Mn [2] NiAl [3] Cu + NiAl [15] Cu + (Ti,Mo)C [16] (Ti,Mo)C [16] Cu + M2C [17] TiC [29] (Ti,Mo)C [29] Cu [33] K carbide [26] k carbide [7] Cu -no Ni [4] Cu -0.75%Ni [4] k carbide [27] NiAl [39] (a)…”

“…Again, no reduction of the uniform elongation was observed, suggesting a small increment (0.6 nm in diameter) in the size of precipitates while maintaining a high number density (in the order of 10 24 m −3 ) through nano-scale-co-precipitation can produce a large strength improvement (43% increase from 434 MPa to 622 MPa) at no expense of ductility. On the contrary, Ni3Ti [14] Cu + NiAl -4%Ni [1] Cu + NiAl -2.5%Ni [1] NiAl -3%Mn [2] NiAl -no Mn [2] NiAl [3] Cu + NiAl [15] Cu + (Ti,Mo)C [16] (Ti,Mo)C [16] TiC [29] (Ti,Mo)C [29] k carbide [7] k carbide [27] NiAl [39] (b) Figure 3. A compilation of (a) yield strength increment and (b) ductility change against precipitate size of various precipitate strengthened steels.…”

“…Some recently investigated precipitates [2][3][4]7,[14][15][16][17][18] in steels from year 1987 to 2017 are listed in Table 2. These nano-scale precipitates are metastable.…”

Optimisation of Mechanical Properties of 18%Ni350 Grade Maraging Steel Using Novel Heat Treatment

“…from early 1960-s [3][4][5][6][7][8][9][10][11]. Mechanism and kinetics of precipitation depending on the chemical composition of maraging steel and parameters of heat treatment and in particular the early stages of precipitate strengthening were a subject of numerous research studies [12][13][14][15][16][17][18][19] and have not been fully understood till date.…”