Continuous-cooling transformation

Continuous cellulosic fibers, 20 557 Continuous compression filters, 77 379-381 Continuous conveyors, 9 119 Continuous cooling, in austenite transformation, 23 282-283 Continuous-cooling transformation (CCT) diagrams, 77 16 23 280 Continuous copper-drossing process, 74 745-747... 

Fig. 18. Continuous-cooling transformation diagram for a Type 4340 alloy steel, with superimposed cooling curves illustrating the manner in which transformation behavior during continuous cooling governs final microstmcture (1). Ae is critical temperature at equiHbrium. Ae is lower critical...

Fig. 7.12 Schematics of (a) tool position vs. time, (b) thermal cycle with superimposed continuous cooling transformation curve, and (c) pseudobinary phase diagram. Positions a" through "i" on the diagrams correspond to Fig. 7.13(a) through (f) and are used to describe microstructural evolution in the stir zone for friction stir welding on Ti-6AI-4V.

As a first step the steel is placed in one of five grades by means of Table 4.3. These grades are based on welding tests, on studies of the continuous cooling transformation behaviour of steels, and on an empirical formula relating composition to maximum HAZ hardness ... 

Atkins M Atlas of continuous cooling transformation diagrams for engineering steels . British Steel Corporation, Sheffield, 1977. 

Fig. 3.1-113 Continuous-cooling-transformation (CCT) diagram for a 4130 grade low-alloy steel. Acs and Ac signify the temperatures of the y/ y+a) and eutectoid reation, respectively. A - austenite, F - ferrite, B - bainite, P - pearlite, M - martensite. The cooling rate is measured at 705 °C. The calculated critical cooling rate is 143 K/s [1.80]...

This critical cooling rate ( q ) has been estimated by use of isothermal time-temperature transformation ( IT T) diagrams (Uhhnann 1972) or continuous cooling transformation (CT) curves Onorato and Uhlmann 1976). 

Fig. 31. Continuous-Cooling-Transformation (CCT) diagram for TRIP 700 (measured at Gleeble3500 ). The following experimental procedure/material is used heating (austenitization) up to 1350 °C, holding time 1 s, dT/df = 337.5 °C/s, austenite grain size 3.0 (ASTM E112), material cold rolled strip, thickness 1.8 mm, Ms = 400 °C, Ac = 735 °C, Ac3 = 1000 °C.

Fig. 60. Schematic illustration of a two-stage continuous cooling transformation (C.C.T.) behavior for Al-rich amorphous alloys and two kinds of cooling curves.

Effect of heat-to-heat variations, within specification, on continuous cooling transformation. 

Figure 9.23 Schematic of "Continuous Cooling Transformation (CCT)" curves 219] (Repainted with permission of Wiley).

Figure 10.13 Continuous cooling transformation (CCT) diagram of 9Cr-ODS steels.

La Carrubba, V., Piccarolo, S., Brucato, V. Solidification of syndiotactic polystyrene by a continuous cooling transformation approach. J. Polym. ScL Part B Polym. Phys., 45,2688-2699 (2007). 

Given the isothermal transformation (or continuous-cooling transformation) diagram for some iron-carbon alloy, design a heat treatment that will produce a specified microstructure. 

It is important to note that the treatments relating to the kinetics of phase transformations in Section 10.3 are constrained to the condition of constant temperature. By way of contrast, the discussion of this section pertains to phase transformations that occm with changing temperatirre.This same distinction exists between Sections 10.5 (Isothermal Transformatiorr Diagrams) and 10.6 (Continuous-Cooling Transformation Diagrams). 

Superimposition of isothermal and continuous-cooling transformation diagrams for a eutectoid iron-carbon alloy. 

With regard to the representation of the martensitic transformation, the M(start), M(50%), and M(90%) lines occur at identical temperatures for both isothermal and continuous-cooling transformation diagrams. This may be verified for an iron-carbon alloy of eutectoid composition by comparison of Figures 10.22 and 10.25. 

Figure 10.27 Continuous-cooling transformation diagram for a eutectoid iron-carbon alloy and superimposed cooUng curves, demonstrating the dependence of the final microstructure on the transformations that occur during coohng.

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