Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7971958 | Materials Science and Engineering: A | 2018 | 30 Pages |
Abstract
We describe here the aging characteristics and strengthening behavior of a low-carbon medium-Mn Cu precipitation-strengthened steel. Atom probe tomography (APT) was employed to characterize the evolution of Cu-rich precipitates in terms of mean radius, number density and volume fraction. Aging at 500â¯Â°C and 550â¯Â°C for 1â¯h resulted in substantial coherent body-centered cubic (bcc) Cu-rich precipitates with mean radius of 1.35 and 2.59â¯nm, respectively. The precipitation strengthening mechanism for these two aging conditions was shearing mechanism and the corresponding strengthening contribution was ~â¯266 and ~â¯312â¯MPa, respectively. Here, coherency strengthening and modulus strengthening played a major role, while the contribution of chemical strengthening was relatively small. With increased aging temperature to 600â¯Â°C, the precipitates grew and coarsened to elongated shape with incoherent face-centered cubic (fcc) structure, and the strengthening mechanism was Orowan mechanism with a contribution of ~â¯232â¯MPa. Increasing the aging temperature also facilitated the formation of retained austenite, which was of great benefit to plasticity without pronounced deterioration on precipitation strengthening. Ultra-high yield strength of 1020â¯MPa with superior total elongation of 25.8% was obtained in the sample aged at 600â¯Â°C for 1â¯h. The excellent mechanical properties derived from the combination of precipitation strengthening by Cu-rich precipitates and plasticity effect of retained austenite can be considered as a design principle to simultaneously optimize strength and ductility.
Related Topics
Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
Y. Zou, Y.B. Xu, D.T. Han, Z.P. Hu, H. Song, R.D.K. Misra, L.F. Cao, S.Q. Chen,