Prediction of solid state structure based on eutectic and eutectoid transformation parameters in spheroidal graphite irons

Abstract

The aim of the present work is to predict experimentally the structural trend of liquid iron based on its solidification features and the subsequent solid state transition. Both transformation processes in SG iron samples are simultaneously studied by means of industrial thermal analysis techniques. Experimental parameters are established in both cases in order to quantify the main metallurgical facts and correlate them with the structural properties of different alloys used in real manufacturing processes. A computer aided program has been designed for the treatment of the cooling curves.A large number of experimental tests using different chemical compositions were made. After curves treatment, several studies have been conducted to correlate the thermal parameters obtained and the structural properties detected via metallographic inspections. The influence of the solidification parameters on carbon diffusion process and the resulting structures is discussed. A new structural model was developed in order to predict the ferrite content on the basis of thermal evolution of SG iron. Nucleation potential (inoculation grade), carbide formation tendency and solid state evolution of metal are evaluated and final structure distribution is accurately estimated.

Thermal Analysis of the Formation of Chunky Graphite during Solidification of Heavy-section Spheroidal Graphite Iron Parts

“…Owing to the relationship between cooling curves characteristics and microstructure features, thermal analysis has thus been developed for obtaining information regarding graphite morphology [1][2][3][4][5][6] as well as nucleation potential of graphite during solidification and inoculation efficiency. [7][8][9][10] It has been further extended for latent heat evaluation 4,[11][12][13] and for improving process variables, [7][8][14][15][16][17][18] e.g. with the aim at predicting final mechanical properties and hardness values 19,20) or for minimizing casting defects such as shrinkage tendency.…”

90 years of thermal analysis as a control tool in the melting of cast iron

“…16: Determination of the dendritic coherency point [10] Fig. 18: Critical parameters of the cooling curve for the region of solid-state transformation [41] (a) (b) (b) 0.4 K•s -1 cooling rate [40] (a) (b)…”

Influence of treatments using different magnesium ferroalloys on the melt quality and the solidification processes of ductile irons

“…Como consecuencia de ello, se ha publicado un considerable número de trabajos que relacionan las características de las curvas de enfriamiento con diversas características del metal [1 y 2] , permitiendo cuantificar su aptitud a la hora de ser utilizado en la fabricación de piezas. En este sentido y dentro de las fundiciones esferoidales, existen tres aspectos críticos a tener en cuenta: la densidad de nódulos o grafitos con forma esferoidal obtenida [3][4][5][6] , la contracción del material [3 y 7-8] a lo largo de la transformación líquido-sólido y el tipo de estructura matricial en la fase metálica a la temperatura de trabajo [5] . Estos tres aspectos definen las características del material fabricado y condicionan en gran medida su validez de cara a una determinada aplicación tecnológica.…”