Effect of Isothermal Heat Treatment Time on the Microstructure and Properties of 4.3% Al Austempered Ductile Iron

Abstract

This study aimed to investigate the effect of replacing silicon with 4.3% aluminum on the kinetics of the bainitic transformation and its effect on the physical properties of cast iron with a chemical composition of 3.4% C, 4.3% Al, 0.32% Si, 0.04% Mg. First, the samples were prepared to the same dimensions followed by austenitization for 2 hours at 900 °C; Then, austempering was performed on the samples at four temperatures i.e., 375 °C, 400 °C, 425 °C, and 450 °C (hightemperature region) for different periods (1-512 min). Microstructural studies were performed by both optical and electron microscopes and it was found that with an increase in the austempering temperature, the thickness of the bainitic ferrite plates increased from 0.31 μm at 375 °C to 0.63 μm at 450 °C and a coarser microstructure was obtained. The results of this study showed that the austempering transformation in Al-alloyed ductile iron will result in the formation of an ausferritic structure.

Mechanism Analysis for the Enhancement of Low-Temperature Impact Toughness of Nodular Cast Iron by Heat Treatment

“…Heat treatment is a kind of technology by conducting heating and cooling process to adjust the microstructure, and thus improve the needed mechanical properties and enhance the service life of components in engineering applications [9][10][11][12][13]. For nodular cast iron, heat treatment is a key process; not only can the matrix structure of nodular cast iron be adjusted by heat treatment to improve its performance, but also the nodulation of graphite and the distribution of alloying elements can be modified, and therefore, a much better comprehensive properties can be obtained [14,15]. It was reported that through appropriate heat treatment processes, the impact toughness of ductile iron under low-temperature conditions can be markedly enhanced, thereby avoiding the brittle fracture.…”

Concrete Surface Crack Detection with Convolutional-based Deep Learning Models

“…In recent years, an increasingly prominent pattern has emerged where machine learning and deep learning models are being utilized for image analysis across a range of applications, encompassing image recognition, classification, and segmentation in the realms of engineering and medicine [2][3]. However, in contrast to conventional and traditional methods employed in diverse civil engineering applications [4][5][6][7][8][9], deep neural networks, functioning as end-to-end learning models, exhibit the capability to automatically extract features from images. The fusion of deep learning and image analysis has ushered in a transformative era in the domain of structural assessment.…”

Effect of Ultrasonic Treatment on Microstructure and Properties of 2000 MPa Ultra-High-Strength Steel-Welded Joints

“…In addition, Ji Xiangyu et al [25] analyzed the formation and evolution mechanism of residual stress during the solid solution heat treatment process of 316L/Q235B composite plates and reduced the level of residual stress by improving the solid solution heat treatment process; Liu Zichen et al [26] used simulation to elucidate the impact of post weld heat treatment differences on the relief effect of residual stress; B. Shakeri et al [27] investigated the mechanism of the effect of cast iron phase transformation on residual stress under isothermal heat treatment; E. Heidari et al [28] provided the possibility of improving the mechanical properties of materials via ablation and rolling methods.…”