Study on the Influences of Adding Rare Earth Ce on the Precipitation Behaviors of TiN Inclusions in 20CrMnTi

Abstract

The morphologies and sizes of TiN inclusions in gear steel 20CrMnTi have a significant impact on its service performance. This paper selects rare earth Ce to modify TiN inclusions in 20CrMnTi. The inclusions are analyzed by SEM (scanning electron microscope), EBSD (electron back-scattered diffraction), EDS (energy disperse spectroscopy), and OTS statistical software, and Thermo-Calc software is used to calculate the inclusion formations. The inclusions of MgAlO4-Ce and CeAlO3 can be formed when rare earth Ce is added into 20CrMnTi, which becomes TiN nucleation core after precipitation. Without the addition of rare earth Ce, square TiN inclusions ranging from 2 to 5 μm account for 60% of the total inclusions in 20CrMnTi. After adding rare earth Ce, the TiN inclusions in 20CrMnTiCe account for 36.7% of the total inclusions. Due to the new phase formations of MgAlO4-TiN and CeAlO3-TiN with sizes less than 2 μm, the titanium-containing inclusions are refined. Fatigue tests are conducted on the steels before and after the addition of Ce. The average fatigue lives of 20CrMnTi do not reach 107 times, and the deviations between the maximum and minimum fatigue lives are great. Large-sized TiN are the main inclusions that affect the fatigue performance of 20CrMnTi. The average fatigue lives of 20CrMnTiCe exceed 107 times, and the deviations of the fatigue lives are smaller than those of 20CrMnTi.

The Influence of Rare Earth Ce on the Microstructure and Properties of Cast Pure Copper

“…At a temperature of 1200 • C, the presence of the rare earth element Ce in copper can lead to the formation of various reaction products. By utilizing the corresponding thermodynamic data [18][19][20][21], it becomes possible to predict the thermodynamic conditions and sequence of formation for rare earth impurities in copper through reactions between Ce and main elements O and S. Table 1 presents the reaction products as well as the activity product of Ce with O and S in liquid copper. At a temperature of 1200 • C, the activity coefficient of rare earth Ce, when added to the main elements in the multi-component copper system, is as follows [20]: ƒ Ce = 0.9890, ƒ o = 0.4537, and ƒ s = 0.6405.…”

“…These newly formed equiaxed grains continue to grow while solute redistribution during grain growth generates another composition undercooling zone at the solid/liquid interface front surrounding grain growth. This facilitates continuous nucleation and growth at these sites, thus promoting the expansion of the equiaxed crystal region [21]. Secondly, upon adding rare earth to copper, preferential reactions between rare earth elements and other constituents lead to the formation of high-melting-point compounds which are finely dispersed throughout the molten copper matrix.…”

The Effect of Point Defects on Young’s Modulus of the Off-Stoichiometric Al3X (X = Li, Sc, and Zr) Phases: A First-Principles Study

“…Yi et al [23] found that the doping of Sc had positive effects on the enhancement of creep resistance in the Al-Ce alloy. Ce promoted the formation of second phases and grain refinement [24,25], and Ekaputra et al [20] found that the combination of the Al 11 Ce 3 and L1 2 -Al 3 (Er, Sc, Zr) precipitates increased the strength of the aluminum alloy. It was found that the addition of Er to the Al-Sc alloys promoted the formation of an Al 3 (Er, Sc) structure, improving the elastic properties of Al alloys [21,22].…”

Titanium Impurity Control in V-Bearing Pig Iron Prepared via the Sodium Smelting of Vanadium–Titanium Magnetite

“…It is easy to combine titanium with these three elements during the steelmaking process to form inclusions such as TiO 2 and Ti(C,N), which pose a great threat to the performance of steel [16,17]. Therefore, some specialized steel grades, such as electrical steel, bearing steel, spring steel, etc., have strict requirements for the Ti content in the steel [18,19]. Generally, the control of titanium mainly focuses on the steelmaking stage.…”