The Influence of Microstructure on the Bendability of Direct Quenched Wear Resistant Steel

Abstract

The influence of chemical composition and processing parameters on the microstructure and bendability of three thermomechanically rolled and directquenched wear resistant steel plates is studied. Overall, the bendability of the steels is good, but there are exceptions that are given special attention. The prior austenite condition and final microstructure is evaluated with respect to subsurface hardness and bendability. The possible effect of inclusions on bendability is taken into account. Away from the surfaces, the samples consisted mainly of auto-tempered martensite. Lowering the finishing rolling temperature (FRT) increased the total rolling reduction below the recrystallization temperature leading to pancaking of austenite and the formation of increasing fractions of polygonal ferrite (PF) and bainite near the plate surface together with an increased intensity of the shear texture component {112}<111>. Strength increased with increasing austenite pancaking provided the microstructure remained mostly martensitic. A homogeneous, largely martensitic microstructure extending across the plate thickness seemed to ensure good bendability. Microstructures that are inhomogeneous with respect to the hardness of the microconstituents, or highly ferritic, or microstructures with an intense {112}<111> shear texture component combined with elongated martensite-austenite (MA) plates in the subsurface layers resulted in the largest minimum useable bending radii.

Effect of the intercritical annealing in the formability and microstructure of a medium Mn steel sheet

“…However, this parameter was very small in the transverse direction in comparison with longitudinal one, a fact that can be caused by the strong crystallographic texture that steel acquired during the hot rolling. This result is consistent with the one published by Kaijalainen et al [13] since they argued that bendability in the transverse direction in a conventional steel was affected by the presence of martensite-austenite plates aligned in the rolling direction and the predominantly shear texture {112}<111> component. Regarding the CBA of the IA samples, it was observed that the highest value was achieved in the longitudinal direction (103.1°), however in this case the difference between longitudinal and transverse was only 8°, which indicates that IA treatment improved markedly the bending properties of the steel sheet.…”

Friction and Wear Behavior of NM500 Wear-Resistant Steel in Different Environmental Media

“…Compared with high manganese steel and high chromium cast iron, as a widely used low alloy high strength wear-resistant steel, NM500 has the advantages of low cost and easy processing [3][4][5][6]. It corresponds to the AR500 grade under the ASTM standard.…”

Changes in microstructure and mechanical properties during the bending process of NM450 wear-resistant steel

“…The bending performance can be improved by lowering the hardness and improving the uniformity of the microstructure at the surface and subsurface layer, which increase the uniformity of the strain distribution along the bending axis [6]. During the bending process, the large size brittle martensite-austenite (MA) constituents or inclusions at the sub-surface layer are broken or separated from the matrix, easily giving rise to the cavities, thus forming the bending cracks [7].…”