Understanding ferrite deformation caused by austenite to martensite transformation in dual phase steels

During the production of DP steels, the volume expansion and shape change accompanying the austenite to martensite transformation is accommodated by the deformation of surrounding ferrite grains. The extent of the deformation in ferrite grains ultimately affects the mechanical properties of DP steels. Using electron backscatter diffraction...

Micro and nanoscale characterization of complex multilayer-structured white etching layer in rails

Micro- to nano-scale characterization of the microstructures in the white etching layer (WEL), observed in a Dutch R260 Mn grade rail steel, was performed via various techniques. Retained austenite in the WEL was identified via electron backscatter diffraction (EBSD), automatic crystallographic orientation mapping in transmission electron...

Modeling and analyzing autogenous shrinkage of hardening cement paste

In this paper, a conceptual model for analyzing the plastic part of autogenous deformation of cement paste based on the Arrhenius rate theory will be presented. The autogenous deformation will be calculated from the elastic deformations with inclusion of creep. Different kinds of cement paste with a water cement ratio 0.3 are tested and studied,...

Thermostatistical theory of plastic deformation in metals

This work aims to describe plastic deformation and microstructure evolution of metals at various scales in terms of dislocation behaviour. The theory is based on statistical thermodynamics, where the entropy is proposed to incorporate the possible paths for dislocation motion. Other than estimating the velocity gradients a dislocation may reach,...

Dislocation climb in two-dimensional discrete dislocation dynamics

In this paper, dislocation climb is incorporated in a two-dimensional discrete dislocation dynamics model. Calculations are carried out for polycrystalline thin films, passivated on one or both surfaces. Climb allows dislocations to escape from dislocation pile-ups and reduces the strain-hardening rate, especially for fully passivated films....

Evaluation of Plastic Deformation During Metal Forming by Using Lode Parameter

In the present research, the relationship between the strain increment and Lode parameter was obtained by using Lode parameter and Levy-Mises equation. The quantitative relation between different strain increments was presented and the relationship between plastic deformation types and Lode parameter was demonstrated. The relations between...

Amorphous-amorphous transition in glassy polymers subjected to cold rolling studied by means of positron annihilation lifetime spectroscopy

In this study, polycarbonate (PC) and polystyrene (PS) are subjected to plastic deformation by means of cold rolling and the resulting variation of the free volume and its subsequent time evolution after rolling is investigated by means of positron annihilation lifetime spectroscopy (PALS). The value of the long lifetime component that is...

A stripyield model including effects of hold periods at constant load

Utilising the NLR Stripyield cycle-by-cycle fatigue crack growth model a basic description of the time dependent effects associated with periods of constant load level has been added to model Fatigue-Creep interactions. An outline of the basic Creep model is given along with flow diagrams of the sub programs added to the Stripyield model. Other...

Analysis of crack opening behaviour by application of a discretised strip yield model

The crack opening behaviour of a fatigue crack in a centrally cracked panel was studied using a discretised version of the Dugdale and Barenblatt model. The effect of crack growth was also included. Results obtain ed for constant amplitude loading were in agreement with data reported in the open literature. The effect of application of single...

TEM "in situ" straining and bulk studies of the selection of glide systems in f.c.c. single crystals

Plastic deformation of f.c.c. single crystals was studied by means of straining experiments inside a transmission electron microscope on Cu foils and some related bulk straining experiments on Cu and Al single crystals. In the foils and bulk crystals with the same orientation of the normal to the large face the same non-primary glide...