Horizontal CCMs in small-capacity metallurgy

Production of light-section rolled products and wire rods of alloyed steel grades differs by small volume of yearly output and wide range of smelted grades. To organize production of light-section rolled products of alloyed steel grades in small volumes, OJSC “Spetsmash” elaborated concept of small-capacity production, which was implemented at several plants. It was shown that horizontal CCM can be effectively applied in the small-capacity production within complexes of light-section rolled stock of alloyed steels production. At the plant “Ferrotrade” (Beloretsk) when creating a complex for production wire rods of 6.5 mm diameter of austenite class steels and nickel-based alloys, a horizontal CCM was constructed. Production of 60 mm diameter billets by the machine was mastered, which enabled to apply a rolling mini-mill, characterizing by small dimensions and power. The horizontal CCM, constructed in 2016 at the steelmaking shop of CJSC “Izhevsk pilot-mechanical plant”, was equipped by electromagnetic stirrer (EMS). It was noted that EMS was applied for the first time in domestic metallurgy at the industrial CCM of horizontal type. In the process of this CCM mastering, more than 60 heats were casted into billets of 80, 200 and 120 mm diameter. EMS application resulted in improving average point on the central porosity to 1.2—1.8 depending on the stirring modes. In 2018 the OJSC “Spetsmash” for the Research Center “Thermodeform” (Magnitogorsk) constructed an experimental horizontal CCM, designed for casting of billets of 40—60 mm diameter by direct casting of melt from the crucible of 60 kg induction furnace into the metal reservoir 776 of the machine. Development of a project of horizontal CCM for PJSC “PlasmaTek” (Ukraine, Vinnitsy) finished, designed for production of billets of 50 and 60 mm diameter within a complex of equipment for manufacturing welding electrodes not only of alloyed but also of carbon steel grades. The designed productivity of the complex is 12,000 t/year. Basic technical characteristics of the CCM presented. Small-capacity production with horizontal CCMs can be organized as independent objects and within existing steel-works for expanding product range.

Properties Comparison of Ti-Al-Si Alloys Produced by Various Metallurgy Methods

Melting metallurgy is still the most frequently used and simplest method for the processing of metallic materials. Some of the materials (especially intermetallics) are very difficult to prepare by this method due to the high melting points, poor fluidity, or formation of cracks and pores after casting. This article describes the processing of Ti-Al-Si alloys by arc melting, and shows the microstructure, phase composition, hardness, fracture toughness, and compression tests of these alloys. These results are compared with the same alloys prepared by powder metallurgy by the means of a combination of mechanical alloying and spark plasma sintering. Ti-Al-Si alloys processed by melting metallurgy are characterized by a very coarse structure with central porosity. The phase composition is formed by titanium aluminides and titanium silicides, which are full of cracks. Ti-Al-Si alloys processed by the powder metallurgy route have a relatively homogeneous fine-grained structure with higher hardness. However, these alloys are very brittle. On the other hand, the fracture toughness of arc-melted samples is immeasurable using Palmqvist’s method because the crack is stopped by a large area of titanium aluminide matrix.

Cast Structure in Alloy A286, an Iron-Nickel Based Superalloy

The structure and segregation of a continuously cast iron-nickel based superalloy were investigated. Cross-sectional samples were prepared from the central section of a 150 × 150 mm square billet. The microporosity was measured from the surface to the center and theoretical conditions for pore formation were investigated. A central porosity, up to 10 mm in width, was present in the center of the billet. The measured secondary arm spacing was correlated with a calculated cooling rate and a mathematical model was obtained. Spinel particles were found in the structure, which acted as inoculation points for primary austenite and promoted the formation of the central equiaxed zone. Titanium segregated severely in the interdendritic areas and an increase of Ti most likely lead to a significant decrease in the hot ductility. Precipitates were detected in an area fraction of approximately 0.55% across the billet, which were identified as Ti(CN), TiN, η-Ni3Ti, and a phosphide phase.

Analysis of Internal Defects Appeared in the Continuous Casting

The paper presents the study of internal defects resulting from the continuous casting of steels. The 50 samples were taken from a total of 20 continuously cast bits of different steel grades. The investigation of the causes of internal defects, shown on the analyzed samples, started from the assumption that the secondary metallurgy was performed correctly. The following internal defects have been evident: internal cracks (axial cracks, section cracks), central porosity and marginal punctuation impurities.

Study on 4Cr9Si2 Martensitic Heat-Resistant Steel in CWR

4Cr9Si2 Martensitic heat-resistant steel is inlet valve and the exhaust tappet materials. This paper is based on the constitutive relationship of 4Cr9Si2 Martensitic heat-resistant steel obtained by isothermal compression; a finite element model of Cross Wedge Rolling was build up for 4Cr9Si2 Martensitic heat-resistant steel. In the model the heat conduction between billet and the die, the convection of heat transfer, and the thermal conversion of plastic work and friction work were taken in account, the value of damage was obtained in the rolling and central porosity was analysis. Then verify the correctness of the FEM and feasibility of simulation results by the experiment