Heat treatment paths

These soft steel substrates do not sufficiently support the hard coatings under load, therefore they are not useful for a CVD coated forming tool and need to be post heat treated. " Different heat treatment paths of CVD coated steel tools are possible. The most... 

Table 2. Characteristics of Different Heat Treatment Paths + Good Properties,...

Heat Treatment Path Complexity Hardness Carbide Precipitations on Grain Boundaries Secondary Hardening Distortion, Specific Volume... 

Fig. 18 Length changes of D2/CVD TiN/quench hardened + tempered, heat treatment paths B and D.

Heat treatment may also affect the extent and distribution of internal stresses. These may be eliminated by appropriate annealing treatments which can remove susceptibility to stress-corrosion cracking. This must be explored in any studies of the performance of materials in environments where stress-corrosion cracking is a hazard. In particular cases, stress-relief annealing treatments may result in the appearance of new phases which, while eliminating the stress-corrosion effects, will induce another type of path of attack. This possibility must be kept in mind in assessing the overall benefits of heat treatments applied primarily for stress relief. 

Another path to alloy deposition is via diffusion. In this case different coatings are deposited alternately, and then heat treatment is applied to promote mutual diffusion, thus ending up with an alloy. As a specific example, an alloy of 80% Ni and 20% Cr can be produced by the deposition of alternating layers of 19- m-thick Ni and 6- m-thick Cr. Subsequent heating to 1000°C for 4 to 5 h produces completely diffused alloys of rather high quality as far as corrosion is concerned. Brass can also be produced by interdiffusion of Cu and Zn under suitable conditions. 

For the characteristic properties two representative examples are chosen the CVD TiN coated and post heat treated high alloy tool steel D2 and the low alloy tool steel L3, both heat treated following path D. The complete heat treatment parameters are ... 

The composition, structure and superconducting properties of high Tc oxide superconductors, La-Sr-Cu-0 and Y-Ba-Cu-0 systems have been investigated. From comparative studies of effects of partial replacements of metal sites by other elements, a low dimensional nature of conduction path was suggested in both oxide systems. Critical relevance of oxygen deficiency and the conditions of heat treatments to the evolution of superconductivity, is discussed in terms of the relatively large nonstoichiometry found in these systems. 

Figure 3.6 Most common evolution paths for phase transformations of aluminum hydroxides and oxides upon heat treatment.

For bodies of big wall thickness the initial creation of open porosity is critical [Cal 90]. During heat treatment the evaporation and decomposition of the polymers generate gas inside the body. If the pores are not open or there are not enough paths to channel the gas to the surface of the exttu-date, pressure will build up inside the body and cracks will be created dur-... 

Ternary alloys in the vicinity of Y disilicides revealed different phase equilibria depending on the heat treatment the phase distribution as derived from alloys in as-cast condition is shown in fig. 49b. The solubility of Al in YSij 55 (AlB2-defect type) in both cases of as-cast and annealed alloys was claimed to proceed along an unusual path similar to the solution of Ni in YSij 55 (see Y-Ni-Si) the maximum solubility of Al at 500°C was shown to be at 15 a/o Al (Muravyova et al., 1971). 

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