Thermo-mechanical treatments

Meyer, M., Muhlbach, R., and Harzer, D. (2005). Solubilisation of cattle hide collagen by thermo-mechanical treatment. Polym. Degrad. Stab. 87,137-142. 

The typical dependence of mechanical properties of Ti-Si binary alloys in as-cast and as-deformed states is shown in Fig. 3. It is seen that in as-cast state room temperature plasticity decreases with increase of silicon content, reducing practically to zero at silicon content of 2-3 wt. % then it raises a little at eutectic formation. Unfortunately, our attempts to increase room temperature plasticity in as-cast condition more or less substantially via employing various kinds of heat treatment procedures were not successful. At the same time, using thermo-mechanical treatment (forging at temperature 1050 °C), it was possible to increase plasticity of deformed alloys essentially. 

Thermal shock resistance of Cr-Re alloys was sufficient to withstand conditions similar to those imposed by the application. The ability to mechanically twin permitted the accommodation of thermal deformation in the boundary area between the hot and cold zones of the combustion chamber, which is acknowledged to be the its most solicited area. Grain boundary micro cracking on the thermally shocked surface might be overcome by strengthening of the grain boundaries through thermo mechanical treatment. 

Avoid adverse effects of thermo-mechanical treatment... 

When exposed to neutron irradiation, heat resistant austenitic alloys tend to embrittle above 500 °C caused by (n,a) transmutations. The effect can be measured by tensile and creep testing. Special thermo-mechanical treatment of the alloys was found to successfully improve their ductibility [32]. 

In order to transform the polymers into medical devices such as tubing, caffieters and other medical items, polymers have to be processed by different techniques, such as extrusion, moulding, spinning and dip coating. Several additives are used to facilitate the processing and improve the properties of polymers. They also increase the stability of polymers during thermo-mechanical treatments. A schematic view of... 

The list of applications seems endless a wide range of properties from corrosion resistance to high tensile strength is covered. These properties depend on the percentage of carbon, the alloying elements, and increasingly on the thermo-mechanical treatments that aim at optimizing the microstructure. 

Future research will address some actual issues such as the difficulty sometimes to disperse the natural filler with some biopolyesters, to achieve excellent filler/ matrix compatibility, and to decrease the impact of the thermo-mechanical treatment on the compounds. 

In the modified approach a thermo-mechanical treatment was devised, where the final reheating temperature was lowered to around 1100°C (to ensure very low finishing temperature) and adequate final reduction of 25%, so as to derive adequate driving force for recrystallization during subsequent solution treatment. Figure 2 shows the flow chart for manufacture of ring forgings. 

The microstructure refinement from the modified thermomechanical treatment is responsible for enhancement of tensile strength and ductility by 18% and 25% respectively. Simultaneously, the stress rupture life as well as ductility is enhanced by virtue of controlled grain size and uniform carbide distribution brought about by the thermo-mechanical treatment. 

Mechanical Properties. Elastic properties of TiAl-based materials are compiled in Table 3.1-32. Strength, ductility, and toughness of the TiAl-based alloys are sensitive functions of both composition and microstructure which is controlled by prior processing [1.59]. Characteristic data are shown in Table 3.1-33 for various alloys. Different property data for the same alloy composition indicate the effect of different prior thermo-mechanical treatments. It is noted that TiAl-based alloys are prone to hydrogen/environmental embrittlement depending on the amount of q 2 from Ti3Al [1.60]. Creep and fatigue data are available [1.59,61]. 

Pommet M., Morel M.-H., Redl A., Guilbert S. Aggregation and degradation of plasticized wheat gluten during thermo-mechanical treatments, as monitored by rheological and biochemical... 

In order to monitor the mechanical properties in relation to the microstructure, the knowledge of the precipitation state at the end of a thermo-mechanical treatment is of prime importance. In this purpose, Arcelor develops models that allow for the prediction of the influence of the process parameters on the state of precipitation. The model Multipreci, developed at IRSID is one of them. It (Hedicts the precipitation kinetics of mono- and di-atomic particles in ferrite and austenite as a function of the time-temperature history. It is based on the classical theories for diffusive phase transformation and treats simultaneously the nucleation, growth and ripening phenomena. The state of precipitation that is predicted includes the particle size distribution, their number and volume fraction. From these values, the effect of the precipitates on the mechanical properties can be calculated. 

Before tests (structural state of alloy—quenched in water after thermo-mechanical treatment and annealing 2 h at 1100°C) 540 890 35... 

R.L. Klueh, N. Hashimoto, P.J. Maziasz, New nano-particle-strengthened ferritic/ martensitic steels by conventional thermo-mechanical treatment, J. Nucl. Mater. 367-370 (2007) 48-53. 

Fig. 3.49 for mechanical loads, that will force the unloading from A to C and a residual compressive stress will remain on the external surface. Alike point A any other element of material gone beyond yield point will rest in a residual stress state, which will be compressive on one side and tensile on the other, as shown in Fig. 3.68. This simple process is used in the most important thermo-mechanical treatment known as induction heating stress improvement (IHSl) developed in the 70s in the nuclear field to eliminate corrosion problems on sensitized stainless steel [66-69]. Its purpose is to eliminate tensile residual stress generated on the inner surface of a pipe made of austenitic stainless steels by a welding process.

Sullivan, (1990-93) Finite element model for thermal decomposition of composites Added a consideration of pressure effects and thermal expansion to the Henderson model. Lacked thermo-mechanical treatment of crack formation. [45- 48]... 

Cold water-swelling may be attained by several techniques, but only thermo-mechanical treatment by steam-heated roller-dryers as well as extrusion cooking (- extrusion cooked starches) have gained industrial significance. Dry milling in ball mills or vibratory ball mills are techniques for pilot plant or laboratory use. 

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