Effect of alloying elements on the microstructure-property relationship in thermomechanically processed C-Mn-Si TRIP steels

The effect of additions of Nb, Al and Mo to Fe-C-Mn-Si TRIP steel on the final microstructure and mechanical properties after simulated thermomechanical processing (TMP) has been studied. The laboratory simulations of discontinuous cooling during TMP were performed using a hot rolling mill. All samples were characterised using optical microscopy and image analysis. The volume fraction of retained austenite was ascertained using a heat tinting technique and X-ray diffraction measurements. Room temperature mechanical properties were determined by a tensile test. From this a comprehensive understanding of the structural aspect of the bainite transformation in these types of TRIP steels has been developed. The results have shown that the final microstructures of thermomechanically processed TRIP steels comprise 50 % of polygonal ferrite, 7 - 12 % of retained austenite, non-carbide bainitic structure and martensite. All steels exhibited a good combination of ultimate tensile strength and total elongation. The microstructure-property examination revealed the relationship between the composition of TRIP steels and their mechanical properties. It has been shown that the addition of Mo to the C-Si-Mn-Nb TRIP steel increases the ultimate tensile strength up to 1020 MPa. The stability of the retained austenite of the Nb-Mo steel was degraded, which led to a decrease in the elongation (24 %). The results have demonstrated that the addition of Al to C-Si-Mn-Nb steel leads to a good combination of strength (∼ 940 MPa) and elongation (∼ 30 %) due to the formation of refined acicular ferrite and granular bainite structure with ∼7 - 8 % of stable retained austenite. Furthermore, it has been found that the addition of Al increases the volume fraction of bainitic ferrite laths. The investigations have shown an interesting result that, in the Nb-Mo-Al steel, Al has a more pronounced effect on the microstructure in comparison with Mo. It has been found that the bainitic structure of the Nb-Mo-Al steel appears to be more granular than in the Nb-Mo steel. Moreover, the volume fraction of the retained austenite increased (12 %) with decreasing bainitic ferrite content. The results have demonstrated that this steel has the best mechanical properties (1100 MPa and 28 % elongation). It has been concluded that the combined effect of Nb, Mo, and Al addition on the dispersion of the bainite, martensite and retained austenite in the ferrite matrix and the morphology of these phases is different than effect of Nb, Mo and Al, separately.

Database for structural steel experiments under a distributed collaboration environment

Due to the high requirements of civil infrastructures against the earthquake in Japan, a great number of research organizations have been conducting the structural steel experiments, in particular the seismic tests such as the cyclic loading test and the pseudo-dynamic test, for many years to determine the seismic performances of steel structures. However, the original test data gained by most research organizations are not well stored in an appropriate manner for distribution and possible usage of others. Although a Numerical Database of Steel Structures (NDSS) was developed some years ago to preserve and share experimental data of the ultimate strength tests acquired at Nagoya University, it was not easy to access this database from other computer platform due to the lack of the support of proper communication media. With the rapid development of information networks and their browsers, structural engineers and researchers are able to exchange various types of test data through Internet. This paper presents the development of a distributed collaborative database system for structural steel experiments. The database is made available on the World-Wide Web, and the Java language enables the interactive retrieval efficiently. The applications of the developed database system for the retrieval of experimental data and seismic numerical analysis are validated in the form of examples.

Hope for sufferers of depression

The ultimate goal of the Language of Depression project conducted by linguists at Deakin University and psychiatrists at the Monash Medical Centre in Melbourne is to provide training programs for Acute Hospital staff to identify early their patients who suffer from depression and refer them to consultation- psychiatrists or psychologists for help. To date, only case studies from this project of 40 subjects have been reported. This paper presents the preliminary findings of the study of the language of depressed Acute Hospital patients. The generic structure of the data set will be described; the role and findings of the application of the WordSmith 3 concordance will be outlined; and in particular the semantic matches of features of depression will be presented. These are drawn especially from the application of APPRAISAL analysis. If Acute Hospital patients are listened to with the insights from these findings, with referral, they should receive help to curtail their suffering and be given hope of improvement and even the prospect of recovery from their depression.

In the realm of the hackers

In the late 1980s, Melbourne was the hub of the computer underground in Australia, if not the world. The hackers who formed the underground were not disgruntled computer professionals or gangs of organised criminals. They were disaffected teenagers who used their basic home computers to explore the embryonic Internet from inside their locked, suburban bedrooms. From this shadowy world emerged two elite hackers known as Electron and Phoenix, who formed part of an alliance called The Realm. In the Realm of the Hackers charts Electron's journey from his initial innocent explorations to his ultimate obsession. It vividly recreates the climate of the 1980s, before there was public access to the Internet. The program takes us headlong into the clandestine, risky but intoxicating world of the computer underground to uncover not only how the hackers did it but why.