Selection of Sulfide Morphology in SUS303 during Solidification

Abstract

The sulfide morphology in SUS303 was investigated and the mechanism of monotectic sulfide formation was evaluated. The sulfide of metastable monotectic type was observed at the surface region of ingot with the higher solidification cooling rate and stable eutectic type was observed at the inner region. The formation of monotectic sulfide was promoted by Ca addition and the formation of eutectic type sulfide was promoted by Al addition with the lower oxgen content. It is thought that the nucleation behavior greatly affect the monotectic sulfide formation because of the lower interfacial energy with liquid oxide inclusion. However, solute distribution, undercooling and the decrease of S activity by adding Ca or increasing O content may also influence on the eutectic/monotectic morphology selection.

Study of manganese sulfide precipitation in medium sulfur, non-quenched and tempered steel via experiments and thermodynamic calculation

“…Where T int is the temperature interface, T 0 is the melting point of pure iron (1809 K), m i is the slope of the liquidus line of each solute element according to the pseudobinary Fe-phase diagram, as given in Table 2. The liquidus temperature can be calculated from equation (10) with initial solute concentration.…”

“…Solidus temperature is closely related to both the solute concentration and solid fraction during the end of the crystallization. The relationship between T s and f s can be approximately described by the existing empirical formula [31], as shown in equation (12). In the present research, an iterative computation is used to find a more accurate solid temperature through equations (4)-(11) with f s = 1 and the cooling rate of 0.5°C • s À1 corresponding to the experimental procedure.…”

“…In his work, the sample was heated to 1455°C and partially melted, and the MnS particles were not dissolved, thus the behavior of MnS precipitation was deduced by the heating process and was not directly observed. You et al have calculated the relationship between precipitation temperature and solid fraction during the solidification process [10], and proposed a new model for predicting the type and composition of inclusions. However, this model has considerable limitations for predicting heterogeneous nucleation process or other complicated situation.…”

“…MnS is generally generated from the residual liquid steel with the enrichment of manganese and sulfur during the solidification procedure. Mathematical modeling is an important tool to investigate the formation of MnS, and several models have been proposed and developed to describe the formation process of MnS by previous studies [11][12][13][14][15][16][17]. In this paper, the direct observation of precipita-tion process of sulfides during solidification was investigated by using a high-temperature confocal laser scanning microscope.…”

The Formation and Growth of Sulfides in Free‐Cutting Stainless Steel

“…A variety of theories have been used to explain the formation mechanism of manganese sulfide, it is considered that type I sulfide formed by metastable monotectic reaction or precipitated from solidoid, and type II sulfide inclusion formed by monotectic reaction or eutectic reaction . Increasing the oxygen content conduce to type II sulfide convert into type I sulfide, according to Oikawa et al calculation.…”