Simple and Precise Description of the Transformation Kinetics and Final Structure of Dual Phase Steels

The kinetics of diffusion-dependent phase transformations (including austenitisation of ferrite in dual steels or ferritic nodular cast irons) is very often described by the Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation. This description is not complete when the conversion is only partial due to insufficient overheating, as the equilibrium fraction of ferrite transformed into austenite cannot be determined directly from the JMAK equation. Experimental kinetic curves of partial austenitisation at various temperatures can be fitted using the JMAK equation, but the equilibrium fraction of the newly formed phase for each temperature has to be calculated as a regression parameter. In addition, the temperature dependence of the kinetic exponent in the JMAK equation is quite complicated and cannot be expressed by a simple general function. On the contrary, the equation of autoinhibition used for the description of austenitisation kinetics in present work directly gives the equilibrium fraction at partial conversion. It describes transformation kinetics at various temperatures independently of whether the conversion is complete or partial. Rate constants of the equation of autoinhibition depend on temperature according to the Arrhenius equation. In addition, the equation of autoinhibition has no weakness as the JMAK equation has, which consists in questionable temperature dependence of kinetic exponent.

KAUSALITAS EKONOMI MAKRO DAN GLOBAL TERHADAP PASAR MODAL INDONESIA

This study aims to determine causality macroeconomic variables and the influence of the Indonesian capital market during the period 2001-2017 by means of Granger causality test statistics and test of Multiple Linear Regression. The results of this study revealed that during the period 2001-2017 there is a relationship of causality between the money supply (M2) with the Indonesia Stock Exchange composite index, but there is no causal relationship between the BI rate, inflation, the price of crude oil, gold, exchange rate IDR/USD, Dow Jones and Nikkei 225 index on the Indonesia Stock Exchange composite index over the same period. The results of model testing research at 99% confidence level, obtained adjusted R-square values simultaneously at 98.4%, meaning that changes in the macro economy is able to provide a very significant variation in movement patterns of stock price index in Indonesia's capital market. This is also evidenced by the magnitude of the correlation values obtained in the model by 99.3%, meaning that there is a very close relationship between macroeconomic variables of the Indonesian capital market. However, the partial rate of inflation that occurred in Indonesia in the period 2001-2017 did not have a significant influence on the movement of stock market indices of Indonesia. Keywords: JCI, macroeconomic, globalization