ENGINEERING TECHNOLOGY

Progress has been made in the study of quantitative models of toughness and brittle transformation of body-centered cubic metals


Recently, Han Weizhong’s research group of Xi’an Jiaotong University proposed a model for the relative velocity of screw/edge dislocation to determine the toughness and brittle transformation of metal materials through quantitative research on the motion velocity of body-centered cubic metal dislocation, and the relevant research was published in JMST.

Publication page. (Photo courtesy of the research group)

The model shows that the relative motion speed of the screw/edge dislocation controls the process of dislocation proliferation in the material, and realizes the sudden increase of plastic strain in a narrow temperature interval, so that the material changes from brittleness to toughness. In addition, the model covers the effects of grain size, initial dislocation density, and number of dislocation sources on the transition behavior of toughness and brittleness.

Refractory core cube metal is widely used in aerospace, weapons industry and nuclear industry because of its excellent properties, but as the temperature decreases, the material’s behavior from toughness to brittleness greatly limits its processing and application. Whether dislocation motion or dislocation nuclei control the brittle transition has been controversial.

In the preliminary work, the research group proposed a physical model for the relative motion speed of the screw/edge dislocation to control the toughness and brittle transformation of metal materials. However, quantitative research on this physical model is still lacking. Therefore, based on the study of the movement speed of snail/edge dislocation at different temperatures, a quantitative model to control the toughness and brittleness transformation of body-centered cubic metal is proposed.

Based on the theory that the relative motion velocity of the screw/edge dislocation determines the efficiency of the dislocation source, a quantitative model for predicting the toughness and brittleness transformation behavior of body-centered cubic metal is proposed. The new model reveals the contribution of snail/edge dislocation to dislocation proliferation and plastic strain when the relative motion velocity of the screw/edge changes with temperature. In addition, the new model also covers the effects of grain size, initial dislocation density and number of dislocation sources on the toughness and brittleness transition behavior, which provides useful guidance for the strengthening and toughening design of body-centered cubic metals.

The first author of the paper is Zhang Yuheng, and the corresponding author is Han Weizhong. The communication unit is the State Key Laboratory of Metal Material Strength of Xi’an Jiaotong University. (Source: Yan Tao, China Science News)

Related paper information:https://www.jmst.org/EN/Y2023/V141/I0/193



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