*2.1. Materials*

In this approach, investigated steel specimens were prepared through open-air melting followed by remelting in electroslag furnace. The consumable electrodes for ESR were made in a 20 kg air induction furnace with estimated amounts of scrap and ferroalloys. The pouring temperature was about 1600 ◦C, and the metal was cast into 40 mm diameter and 600 mm high vertical chill molds. These were remelted through ESR process with and without inoculation of 0.05–0.07% Ti. The process was carried out in a water-cooled steel mold of 80 mm diameter connected to the negative end of a DC power source. The applied current and voltage were about 730 A and 25 ± 2 V, respectively, with mold water flow rate of 30 L/min and base-plate water flow of 20 L/min. After ESR, cooled ingots were taken out from the mold and homogenized in a muffle furnace at 975 ◦C for 8–9 h. To eliminate the probability of the presence of any cavities or pipes or any other internal defects, about 20 mm and 10 mm lengths were cut from the bottom and top of the ingots, respectively. Each ESR ingot was 20 kg in weight. The ESR ingots underwent forging. The chemical compositions of the four produced steels are given in Table 1. The chemical compositions are similar except for Mo content, which was changed from 0 to 10%. The steels are identified as M0, M2.9, M4.6, and M9.8 with 0.0, 2.9%, 4.6%, and 9.8% Mo, respectively (Table 1).


**Table 1.** Chemical composition (wt%) of produced steels.

#### *2.2. Optical Microscopic Observation*

Initially, specimens were cut into pieces (1 × 1 × 0.5 cm3) from the sheets, and two samples of each grade were used for the tests. The specimens were properly polished with different grades of emery paper (120, 180, 500, and 1000) and cloth polishers. After mechanical polishing, the samples were etched in 10% ammonium persulfate and 10% nital solutions. Microstructural analysis was then performed using a Leica optical microscope (Leica, Wetzlar, Germany).

#### *2.3. X-ray Diffraction (XRD)*

The crystalline structure and phases of the forged steels were characterized by XRD using a Rigaku Ultima III X-ray Diffractometer (Rigaku, Tokyo, Japan) to record diffraction traces from monochromatic Cu K α radiation applied at room temperature and at a scan rate of 2◦/min. The crystallographic planes of X-ray diffraction were obtained from the inbuilt software of the X-ray machine.
