Three-body abrasive wear of fine pearlite, nanostructured bainite and martensite

18-8 type austenitic stainless steel has been subjected to tension test at a range of strain rates (5×10−4–5×10−2 s−1) and temperatures ( 298–973 K ) to investigate the effect of temperature and strain rate on its mechanical properties. It was found that the serrated flow behavior of this material, one of the evident features of dynamic strain aging (DSA) phenomenon can be divided into two sections according to the temperatures, i.e. the range of 523–673 K and 723–873 K at the strain rate of 5×10−4 s−1. Within these two temperature ranges, one can find some similar rules, for example, the critical strain ec for the onset of serrations reduces with increasing temperature. By calculating the activation energy of the DSA process of the material, it is found that the DSA at lower temperature range is caused by the interaction between (C, Ni) solute atom atmosphere and dislocation, and the DSA at higher temperature range is caused by the interaction between (C, Cr) solute atom atmosphere and dislocations. In order to further investigate the influence of DSA on high temperature strength of the material, the static tensile tests at temperatures of 573, 723, and 873 K, creep tests were also carried out, respectively, after various DSA pre-treatments and cold-working processes. The results show that the high temperature short-time strength and 873 K creep rupture strength of the specimens increase with increasing pre-strain temperature and pre-strain, and the strengthening effect of DSA is higher than that of cold-working at the same pre-strain.

Effect of dynamic strain aging on high temperature properties of austenitic stainless steel

Mechanistic Modeling of Dynamic Strain Aging in Austenitic Stainless Steels

Prediction of mechanical properties of DP steels using neural network model

The temperature and strain rate dependence of yield and work hardening behavior in elevated temperature stress-strain testing was investigated in the nickel-base superalloy UDIMET 115. This alloy was heat treated to produce a bimodal distribution of hyperfine and coarse γ1 precipitates. Yield behavior is shown to be controlled primarily by dislocation pair cutting of the hyperfine precipitates. Stage II work hardening appears to be governed mainly by the dislocation networks generated on the coarse precipitates as these are bypassed under the Orowan mechanism. Analysis of Stage III work hardening using ϕvs σ plots shows that a steady state exists for the stress-strain deformation of this system. Results are also reported on extremely strong serrated flow at moderately elevated temperatures and a high temperature ductility minimum.

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Temperature and strain rate dependence of stress-strain behavior in a nickel-base superalloy

Effects of microstructural parameters on the mechanical properties of eutectoid rail steels

Athermal and temperature dependent behavior of serrated flow in an austenitic stainless steel

On the nature of strain perturbations in the creep curves of austenitic stainless steel

Recently Penny has extended the use of the continuum damage mechanics approach of Kachanov and Rabotnov to the extrapolation of shorter time creep rupture data to longer times. In this paper the authors review the methodology developed by Penny and have applied it using creep data for 9Cr-1Mo and 2.25Cr-1Mo steels that they have tested, as well as using data from the literature. The method appears to provide a reliable method of extrapolation from isothermal data, and can provide an economical and physically justified approach to the development of longer time creep-rupture data.Copyright © 2004 by ASME

Iain Le May

Papers

Effects of microstructural parameters on the mechanical properties of eutectoid rail steels

Athermal and temperature dependent behavior of serrated flow in an austenitic stainless steel

On the nature of strain perturbations in the creep curves of austenitic stainless steel

Extrapolation of Shorter Time Creep Rupture Data Using the Damage Mechanics Approach of Penny

On cell structure and subgrain formation in type 304 stainless steel