This paper presents a finite element simulation of the screw rolling of a bimetallic (BM) pipe workpiece with an outer cladding layer (08Kh18N10T stainless steel/grade 20 steel) produced by explosive welding, followed by experimental testing of the process on a pilot-scale two-high mill with guide shoes. According to the simulation results, during the two-pass rolling of the BM pipe, deformation heating occurs in the layer weld zone, with more intense deformation of the inner base metal layer made of carbon steel. The presence of deformation heating is also confirmed by metallographic analysis, revealing larger ferrite grains and its volume fraction near the layer boundary. It is demonstrated that the screw rolling method enables the production of pipes of a given size without rolling defects and with a high-quality layer bond.
This paper proposes a method for controlling the volume hardness of steel grinding balls. The findings indicate that assessing the internal structure of the balls requires an increased number of hardness measurements across their cross-section. Measurements taken in the central region should be excluded, because once the balls reach a critical size, exceeding the segregation zone, they are removed from the ball mill. The developed method enables a more accurate assessment of grinding ball quality.
Modern equipment used in manufacturing makes it possible to achieve high and stable product quality. Compliance with the specifications and standards required for equipment operation under the severe conditions of the metallurgical industry must be maintained. Heat treatment is one of the key stages in the manufacturing route for products of this class. Automation of heat treatment is critical because it reduces human error, maintains the specified temperature and time conditions, improves energy efficiency and safety, and provides full digital traceability of the treatment history of each part. Together, these functions help ensure stable product quality. A three-level automation system architecture was developed. It includes a SCADA level for monitoring, a programmable logic controller (PLC) level for local control, and a field level with temperature sensors, variable-frequency drives, and actuators. The automation system architecture and functional automation diagram were designed. Software was developed to control temperature conditions, furnace door and hearth position, and protective functions. A visualization system was implemented to display the equipment and process parameters graphically. The implemented multimodal control system for heat treatment reduced the product defect rate by 7
We study the effect of sintering conditions on the microstructure and mechanical properties of sintered chromium-nickel powder steels of the VP 304.200 grade. In the present work, we use the methods of cold pressing, vacuum sintering at 1200 °C, and radial compression of annular samples, as well as the procedures of microstructural and elemental analyses. It was shown that the plasticity and strength characteristics of the material strongly depend on porosity, the distribution of alloying elements (Cr, Ni, Fe), and the presence of oxide inclusions. It has also been established that the zones with elevated oxygen concentration and heterogeneity of the chemical composition play the role of the sites of crack initiation in the process of deformation. The accumulated data make it possible to optimize the modes of sintering and deformation treatment with an aim to increase the stampability and the mechanical characteristics of cylindrical parts.
We study the process of chemical vapor deposition of coatings of the Ni–B system performed by using sodium borohydride as a reducing agent and present an analytic survey of the domestic and foreign works dealing with the methods used for getting Ni–B coatings and investigation of their properties. The prospects of application of these coatings for repairing internal cavities in cooled turbine blades, including the blades intended for subsequent high-temperature vacuum brazing, are demonstrated. The influence of the concentration of reducing agent (NaBH4) on the composition, microstructure, and properties of the coatings has been experimentally analyzed. It is shown that the optimal boron content (5.2–7.9 wt.
