Comparison of Rare Earth Refinement in 4130 and HY100

Abstract

Solidification based grain refinement has gained wide interest by both researchers and industry. This method provides a route for refinement in processes where thermomechanical approaches are ineffective. Prior research into 4130 and HY100 found very different responses when rare earth additions were made. The 4130 was effectively refined while HY100 showed no response. The cause of this difference was not determined. The research presented in this paper examined heats of 4130 and HY100 with rare earth silicide or EGR additions. Characterization included macrostructure examination, mechanical testing, thermal analysis, and electron microscopy. Refinement was observed only in the treated 4130 heats and corresponded to an increase in the peritectic temperature. The HY100 heats had no changes in macrostructure or solidification reactions. Rare earth containing inclusions of similar compositions were observed in the treated 4130 and HY100 heats. These inclusions appear to be a good fit for austenite based on the 4130 data. It was proposed that the unresponsiveness of HY100 was due to the strong segregation of nickel before the peritectic in that alloy. Nickel promotes austenite, and its segregation may provide a stronger driving force for its formation than the energy barrier reduction caused by the presence of rare earth inclusions.

Influence of Rare Earth Ce Additions on Microstructure and Mechanical Properties of Experimental Pipeline Steels

“…Regarding the latter, of particular benefit has been the ability to modify oxide and sulfide inclusions and to prevent the segregation of tramp elements to grain boundaries. [3][4][5] More recently, the rare earths have received renewed attention as a potentially potent alloying agent where they can, for example, refine the as-cast microstructure, [7,8] affect solid-state transformations during thermomechanical processing, [9][10][11][12] and hence dictate the final microstructure of the steel. [12,13] Collectively, the effect of the rare earths has been to offer potential improvement in a variety of steel properties such as ductility, [14] fatigue, [9,15] wear, [16,17] and corrosion [18,19] resistance.…”

Temperature Effect on the Dynamic Young’s Modulus, Shear Modulus, Internal Friction, and Dilatometric Changes in Quenched and Annealed AISI4130 Steel

“…The material used in the current work was a low alloy carbon steel, the AISI 4130, containing chromium and molybdenum as strengthening agents. It is one of the most widely used low alloy steels for various applications due to its improved corrosion and wear resistance, hardenability, and enhanced mechanical strength for high temperature applications [25][26][27][28][29]. When designing and selecting low-alloy steels used in various equipment and structures, elastic and damping properties play a key role.…”

Phase Composition and Temperature Effect on the Dynamic Young’s Modulus, Shear Modulus, Internal Friction, and Dilatometric Changes in AISI 4130 Steel

“…It is also used in machinery parts, for instance, gears, drill bits, cutters, mills, etc. [3][4][5][6][7][8]. The AISI 4130 steel microstructure and properties are very sensitive to heat treatment.…”