Study on the Control of Rare Earth Metals and Their Behaviors in the Industrial Practical Production of Q420q Structural Bridge Steel Plate

Abstract

Rare earth (RE) addition can refine and change the shape/distribution of inclusions in steel to improve its strength and toughness. In this paper, the control of RE, specifically Ce and La, and their behaviors in the practical industrial production of high-strength structural steel with 420 MPa yield strength were studied. In particular, the interactions between RE and Al, Nb, S, O were investigated, with the aim of improving the steel toughness and welding performance. The impact energy of the plate with RE is approximately 50 J higher than the regular plate without RE. The toughness of the plate from ladle furnace (LF) refining with RE addition is better than the one from Ruhrstahl and Hereaeus (RH) refining. The RE inclusions could induce the intragranular ferrite and refine the grain size to the preferred size. After welding at the heat input of 200 kJ/cm, the grain size at the heat affected zone was found to be the finest in the plate from the LF process with RE addition. Notably, the microstructure of ferrite was quasi-polygonal.

Microstructure and Mechanical Properties of Structural Metals and Alloys

“…The major portion of these papers is focused on the mechanisms of microstructure evolution and the mechanical properties of metallic materials subjected to various thermo-mechanical, deformation, or heat treatments [1][2][3][4][5][6][7][8][9][10][11][12]. Another large portion of the studies is aimed on the elaboration of alloying design of advanced steels and alloys [13][14][15][16]. The changes in phase content, transformation, and particle precipitation and their effect on the properties are also broadly presented in this collection [17][18][19][20][21].…”

“…Those readers interested in structural steels may learn much from comprehensive investigations of microstructural changes and their effect on mechanical properties caused by plastic working and heat treatment of diverse steel types [2,7,8,10,12,15,16,[19][20][21][22]. Two of these papers [7,12] present experimental/simulation results of mechanical behavior of high-Mn TWIP steels, which have recently aroused a great interest among material scientists and engineers because of outstanding strengthductility combination inherent in such steels.…”

Effect of Rare Earth Cerium Replacement of Nickel on Cryogenic Toughness of 7Ni Steel

“…At present, many researchers have indicated that adding suitable RE elements can improve the cryogenic toughness index, mainly by refining grains, purifying steel matrix, and changing the morphology of inclusions. [ 1–12 ] Wu et al [ 13 ] investigated RE element on the strength and toughness of Nb‐alloyed steel. The results indicated that the mixed La + Ce RE compound is promising to replace the Nb element to improve the cryogenic toughness of the product.…”

Evolution of Inclusions with Ce Addition and Ca Treatment in Al-killed Steel during RH Refining Process

“…However, for Al-killed steel, some enterprises also carry out Ca treatment after rare earth addition in industrial production. 14) Therefore, this work was undertaken to reveal evolution of inclusions after Ce addition and Ca treatment in RH refining process of Al-killed steel. A SEM equipped with and EDS was employed to characterize the inclusions, and thermodynamic calculation was performed to clarify the modification process of oxide inclusions.…”