EFFECT OF SEVERE PLASTIC DEFORMATION ON STRUCTURE AND PROPERTIES OF AUSTENITIC AISI 316 GRADE STEEL
The article presents results of investigation of structure and properties of austenitic steel grade AISI 316 after application of Equal Channel Angular Pressing (ECAP) at the temperature of approx. 290C. The ECAP method leads to significant improvement of strength of investigated material. Investigation of structure was made by combination of TEM and FEG SEM together with EBSD. Statistic evaluation of angular disorientation and of size of grains/sub-grains was also made with use of electron diffraction (EBSD) in combination with scanning electron microscope FEG SEM Philips. It was proven that the ECAP method enables obtaining of ultra fine-grained austenitic structure. It was established with use of the EBSD technique that after 8 passes through the ECAP die the sub-grains with misorientation angles smaller than 10 formed less than 20% of the final structure. Average size of austenitic grains with high-angle boundaries after 8 passes was approx. 0.1m.
Effect of Severe Plastic Deformation on Structure and Properties of Beta Titanium Alloy Using for Hip Implants
The Paper Deals with Microstructural and Mechanical Properties Changes during Severe Plastic Deformation Process in Beta Titanium Alloy Used for Hip Implants. Effect of Various Numbers of Passes through ECAP (Equal Chanel Angular Pressing) Die on Microstructure and Properties Have been Evaluated. Comparison between Virgin State Cast Alloy and Alloy after Several Steps of Severe Plastic Deformation Induced by ECAP Technology Have been Carried out. Mechanical Properties Have been Evaluated Using Miniaturized Specimens. from Experimental Work can Be Concluded Positive Effect of ECAP Technology both on Mechanical Properties (yield Stress as well as Tensile Strength) Including Grain Size.
Strengthening at intermediate temperatures in iron aluminides
Abstract The strength peak found at intermediate temperatures for Fe 3 Al and FeAl alloys is of interest both from the fundamental point of view and also because such strengthening increases the temperature range where good strength can be obtained. Several theories have been proposed to explain the strengthening involved, but no clear agreement has been reached as to the true mechanisms involved. After reviewing likely strengthening mechanisms, some recent results on mechanical behaviour and dislocation microstructures will be presented. In particular the temperature and strain-rate dependencies of mechanical behaviour in a Fe 3 Al based alloy will be considered, as well as the influence of strain-rate jumps. Dislocations found in deformed samples, both in the as-deformed condition as well as after subsequent annealing treatments, will be discussed. Observations on deformed FeAl samples are shown to suggest somewhat different conclusions than for Fe 3 Al as to the important strengthening mechanisms. Processes such as APB relaxation, local climb, and superdislocation reactions and decompositions may all play roles in determining strength.