Strain point 3x10 No plastic deformation, approximately equals the Tg [Pg.288]

Annealing point 10 Diffusion fast enough to eliminate internal stresses [Pg.288]

Working point 10 Easily deformed but does not flow [Pg.288]

Source From Callister, W.D., Materials Scierwe and Engineering An Introduction, 7th edn., 2007. [Pg.288]

FIGURE 6.30 Constructing a TTT diagram from F(t) curves at several different temperatures, where the F t) curves are constructed from the G(T) and N(T) curves for the transformation process. The TTT diagram provides the time required to achieve certain amounts of transformation as a function of the temperature of the transformation. TTT curves are also known as C curves, because of their characteristic C-hke shape. The C-like shape is due to the fact that both nucleation and growth (and hence the overall transformation rate) peak at intermediate temperatures. [Pg.231]

The homework provides an opportunity to develop a TTT diagram for a solidification process. The process involves three principal steps [Pg.231]

Calculate F t) at 5-10 different temperatures (using values calculated for iV and G at these 5-10 different temperatures). [Pg.231]

LIQUID-SOLID AND SOLID-SOLID PHASE TRANSFORMATIONS [Pg.232]

Differences between Liquid-Solid and Solid-Solid Phase Transformations [Pg.232]

Figure 6.4 The time-temperature-transformation diagram of the iron-carbon system, beginning at the composition of austenite... |

For a number of applications, particularly those associated with conditions of continuous cooling or heating, equilibrium is clearly never approached and calculations must be modified to take kinetic factors into account. For example, solidification rarely occurs via equilibrium, amorphous phases are formed by a variety of non-equilibrium processing routes and in solid-state transformations in low-alloy steels much work is done to understand time-temperature-transformation diagrams which are non-equilibrium in nature. The next chapter shows how CALPHAD methods can be extended to such cases. [Pg.419]

This section will begin by looking at how thermodynamic and kinetic modelling has been combined to understand time-temperature-transformation diagrams in steels. The woric, for the most part, is semi-empirical in nature, which is forced upon the topic area by difficulties associated with the diffusional transformations, particularly where nucleation aspects have to be considered. The approaches have considered how best to predict the time/temperature conditions for austenite to... [Pg.440]

A discontinuous transformation generally occurs by the concurrent nucleation and growth of the new phase (i.e., by the nucleation of new particles and the growth of previously nucleated ones). In this chapter we present an analysis of the resulting overall rate of transformation. Time-temperature-transformation diagrams, which display the degree of overall transformation as a function of time and temperature, are introduced and interpreted in terms of a nucleation and growth model. [Pg.533]

Wei, J., DeMuse, M. and Hawley, M.C., Kinetics modelling and time-temperature-transformation diagram of microwave and thermal cure of epoxy-resins, Polym. Eng. Sci., 1995, 35, 461. [Pg.170]

Construct a time-temperature-transformation diagram for a thermoset that follows a second order reaction kinetic model described by... [Pg.338]

Figure 3. ATS time-temperature-transformation diagram for isothermal cures in N2. |

Fig. 11 Schematic of time-temperature-transformation diagram for alloy indicated in Fig. 10 indicating regions of both heterogeneous and homogeneous precipitation of the p phase in a a matrix. |

Involving the time dependence AFm t) (Equation 1) is close to the thermodynamics of systems with fading memory (Day, 1972) and the TTT type (time-temperature-transformation) diagram, a so-called nose diagram in the spinodal dccompasition theory (Huston et ah, 1966 Cahn, 1968). [Pg.480]

Problem 6.7. Figure 6.42 gives a set of rate of transformation [F(t)] curves for the crystallization of a glass. Using this information, calculate and plot (using a computer program of your choice) a ITT (time-temperature-transformation) diagram for this crystallization that includes curves for 10,50, and 90% transformed with temperature on the vertical axis versus log (time) on the horizontal axis. [Pg.248]

See also in sourсe #XX -- [ Pg.538 ]

See also in sourсe #XX -- [ Pg.120 ]

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