Influence of Rare Earth Metals on Microstructure and Inclusions Morphology G17CrMo5-5 Cast Steel

Abstract

This paper presents influence of rare earth metals (REM) on the microstructure and morphology of non-metallic inclusions of G17CrMo5-5 cast carbon steel The research has been performed on successive industrial melts. Each time about 2000 kg of liquid metal was modified. The REM was in the form of mishmetal of the composition 49,8% Ce, 21,8% La, 17,1% Nd, 5,5% Pr and 5,35% the rest of REM. The rare earth metals were put into the ladle during tapping of heat melt from the furnace.Keywords: Cast steel, modification, rare earth metals, non-metallic inclusions, cerium W artykule przedstawiono rolę metali ziem rzadkich na strukturę i morfologię wtrąceń niemetalowych w staliwie wę-glowym G17CrMo5-5. Badania prowadzono na seryjnych wytopach przemysłowych. Każdorazowo modyfikacji poddawano po około 2000 kg ciekłego metalu. Metale ziem rzadkich wprowadzono w postaci miszmetalu o składzie: 49,85% Ce, 21,8% La, 17,1% Nd, 5,5% Pr i 5,35%. Metale ziem rzadkich wprowadzono do kadzi podczas spustu ciekłego metalu z pieca.

Fracture Energy and Fracture Morphology after Three-Point Bending Test of Welded Joints Made of Cast Steel Designed for Use in Power Sector, with and without the Addition of Rare Earth Metals

“…The inclusions in the modified cast steel are characterized by a much larger dispersion ( Figure 14) and morphology and size changes (Figures 15 and 16). The inclusions formed during the modification process and were mostly oxysulphides ( Figure 17) [32,33]. The REMs addition in the liquid steel caused the inclusions to take on a globular shape and be more evenly distributed in the matrix.…”

“…Evaluated qualitatively, after the heat treatment these changes involved a significant reduction in the ferritic matrix grain size and the reduction of precipitation processes in the modified cast steel during tempering. The transmission electron microscopy showed changes in dislocation density in the steel with the addition of REMs [32]. The samples were etched with the HNO 3 solution in C 2 H 5 OH and examined in a light microscope (LM).…”

“…The production of steel and cast steel containing REMs is difficult and successful modification depends on a number of factors, including adequate deoxidation of the molten metal, the REMs' amount, type and the time the addition is made. Nevertheless, rare earth metals bring a number of benefits in steelmaking by influencing the steel microstructure (grain refinement, non-metallic inclusion modification) and by increasing the strength and corrosion properties and hardness of the steel [25][26][27][28][29][30][31][32][33].…”

Effect of rare earth cerium on the impact toughness, corrosion and wear resistance of CrNiMnMo alloyed lining steel

“…Diffraction peaks for both martensite and austenite were detected in specimen 1, whereas the martensite diffraction peak was found only in specimen 2, therefore little residual austenite was found to be present specimen 1. This structural difference may exist as the austenite grains can be refined by adding rare earth cerium [7][8][9] which helps to improve its properties. Also, the rare earth element can refine the cast grain and reduce interdendritic component segregation which is helpful in allowing the alloy element to dissolve sufficiently in the austenite when the steel is heated to a temperature of over A c3 or A ccm temperature [10].…”

Effect of Tempering Temperature on the Mechanical Properties of Cast L35HM Steel

“…An increase in this temperature improves plastic properties, toughness included [8][9][10][11][12][13].…”