3D Growth of Intragranular Pearlite in an Aged 100Mn13 Steel

Abstract

The morphology and microstructure of intragranular pearlite in 100Mn13 high‐carbon, high‐manganese steel aged at 600 °C are observed by a scanning electron microscope (SEM) and transmission electron microscope (TEM) and analyzed, and growth models describing the morphology and growth process in 3D space are proposed. The results show that pearlite could nucleate directly in the austenite grain and present a 3D morphology after deep etching, and ferrite and cementite in pearlite keep the orientation relationship (OR) with austenite, ( 2 2 false¯ 0 ) γ // ( 10 4 false¯ ) M 3 C , ( 1 false¯ 1 1 false¯ ) γ // ( 01 1 false¯ ) α , ( 0 1 false¯ 1 false¯ ) α // ( 1 false¯ 1 2 false¯ ) M 3 C , and [ 110 ] γ // [ 100 ] α // [ 461 ] M 3 C . Also, the overall continuous ledges at the lamellar ferrite surface and end surround the whole ferrite lamellae, corresponding to a fringe structure and a curved frontier interface in 2D space, which shows a terraced morphology in 3D space. The different structures of the α/γ interface in 3D directions result in different growth rates of ferrite lamellae, that is, edgewise grows fastest along the direction of [ 01 1 false¯ ] α due to the incoherent interface composed of ( 0 1 false¯ 1 false¯ ) α / / ( 1 2 false¯ 1 false¯ ) γ with a 28% mismatch, and sidewise grows slowest along the direction of [ 0 1 false¯ 1 false¯ ] α due to the coherent interface composed of ( 01 1 false¯ ) α / / ( 1 1 false¯ 1 ) γ with a 1.9% mismatch.

Influence of V on the Microstructure and Precipitation Behavior of High-Carbon Hardline Steel during Continuous Cooling

“…Figure 7e shows a phase transition zone between α-Fe and VC, where the ordered arrangement of VC gradually transitions to the ordered arrangement of α-Fe, with VC atoms gradually adjusting their positions to grow in the direction of α-Fe. Liang et al [20] also observed a similar phenomenon in ferritic steel. Based on the Bramfitt two-dimensional misfit degree theory [39] (Equation ( 1)), a two-dimensional misfit degree model for α-Fe and VC was constructed (as shown in Figure 7f), and the misfit degree (δ) between α-Fe and VC was calculated.…”

“…The nano-precipitation of VC can pin the slip of dislocations during deformation, thus increasing the strength of the material [ 19 ]. When precipitates form at austenitic grain boundaries, they can also serve as nucleation sites for pearlite growth [ 20 ]. The precipitation behavior of VC is related to the phase transformation temperature, aging time, and cooling rate [ 21 , 22 , 23 ].…”