Mechanical Properties with Annealing Temperature

The material, upon which these tests were carried out, had been cold worked to the extent of 50 %, and test pieces were cut from it longitudinally and transversely to the direction of rolling. Up to 300° C. the metal was annealed 

The metal was allowed to age for eight days after cooling before being tested. 

It is evident from these figures, that, whatever the rate of cooling and in whatever direction the test pieces are. cut, 

The following table summarises the results obtained on the longitudinal test pieces for these temperatures, after 50 % cold work — 

Anno al Tensile Strength Elastic limit Elonga- tion % Shock Resistance Kg.m. cm.4 

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Chapter I. (a) Variation in the mechanical properties (Tensile Strength, Elastic Limit, Elongation, Shock Resistance, and Hardness) with the amount of cold work. (6) Variation in these mechanical properties with annealing temperature (after cold work). 

Variation of these Mechanical Properties with Annealing Temperature. 

Fig. 56.—Variation in Mechanical Properties with Annealing Temperature. Metal quenched from 475°, reannealed, and cooled very slowly.

The experiments on the variation of mechanical properties with cold work (thin series) and the cupping tests (both in the worked and annealed states) were carried out at the Chalais Meudon Laboratory. The experiments on the effect of annealing at different temperatures after cold work were carried out at the Conservatoire des Arts et Metiers. Reports of the latter experiments are given in the appendices. 

Flo. 45.—Variation in Mechanical Properties (Tensile and Impact) with Annealing Temperature. Metal subjected to 60 % Cold Work, annealed and cooled in air. 

Another exhibition of exceptionally high strength and ductility was also revealed in HPT-produced Ti, when we studied the influence of annealing on its tensile mechanical properties at room temperatures [9], In this case enhanced strength and ductility was observed in CP Ti after HPT and short annealing at temperatures below 300 °C. Let us consider the features of mechanical behavior of this CP Ti with a linkage to its microstructure. 

Structural Properties at Low Temperatures It is most convenient to classify metals by their lattice symmetiy for low temperature mechanical properties considerations. The face-centered-cubic (fee) metals and their alloys are most often used in the construc tion of cryogenic equipment. Al, Cu Ni, their alloys, and the austenitic stainless steels of the 18-8 type are fee and do not exhibit an impact duc tile-to-brittle transition at low temperatures. As a general nile, the mechanical properties of these metals with the exception of 2024-T4 aluminum, improve as the temperature is reduced. Since annealing of these metals and alloys can affect both the ultimate and yield strengths, care must be exercised under these conditions. 

Niobium is always found in nature associated with tantalum and it closely resembles tantalum in its chemical and mechanical properties. It is a soft ductile metal which, like tantalum, work hardens more slowly than most metals. It will in fact absorb over 90% cold work before annealing becomes necessary, and it is easily formed at room temperature. In addition, welds of high quality can be produced in the metal. In appearance the metal is somewhat similar to stainless steel it has a density slightly higher than stainless steel and a thermal conductivity similar to 1% carbon steel. 

It must always be remembered that diffusion coatings are produced by a form of heat treatment and that, with the exception of low-temperature zinc diffusion (sherardising), the treated ferrous materials are usually in the annealed condition. Whenever the mechanical properties of the parts must be restored to their original level, a subsequent heat treatment is necessary . This does not as a rule present any difficulty with chromised or boronised steels. In order to prevent undue distortion and internal stresses during treatment and subsequent hardening, it is recommended that high-carbon and alloy steels should be processed in the normalised condition. 

Poly(arylene ether ketone) and poly(arylene ether sulfone) were also tried to be incorporated into the hybrids with silica gel by means of the sol-gel procedure [19, 20], For example, triethoxysilyl-terminated organic polymer was subjected to co-hydrolysis with tetraethoxysilane. A systematic change in mechanical and physical properties of the hybrid glass has been found with the content of organic polymer and the annealing temperatures. 

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