Obtaining tube blanks from copper-nickel alloy МНЖ 5-1 when using a tool made of die steel adjustable austenitic transformation during operation

Purpose. Production of die tool from steel with regulation of austenitic transformation during operation to increase the level of service life during hot deformation of copper-nickel alloy. Research methods. Metallographic, high-temperature X-ray phase and dilatometric analyzes of research steel. Results. The mode of heat treatment (incomplete annealing) of steel 4Х3Н5М3Ф at a temperature of 750±20 °С, obtained by electroslag remelting, allowed to obtain a perlite-sorbitol structure at a hardness of33–34 HRC and allowed better machining by cutting the workpiece alloy. The proposed mode of final heat treatment (hardening 1030±10 °C and tempering 600±5 °C) of the investigated steel, makes it possible to heat the matrix during operation to a temperature of 600 °C. Scientific novelty. The thermal stability of the tool for hot deformation can be significantly increased when using steel with adjustable austenitic transformation during operation. Such steel in the initial state has a ferrite base, and when heated to operating temperatures occurs from α-Fe to γ-Fe conversion and, subsequently, the austenitic structure is preserved throughout the period of high-temperature operation of the stamping tool. It is confirmed that the stamping tool made of steel 4Kh3N5М3F when pressing a copper-nickel alloy works in the temperature range corresponding to the austenitization process. Practical value. Abbreviated technological operation, namely thermo-deformation processing (forging) of ingots obtained by electroslag remelting. Experimental-industrial tests of the die tool of steel 4Х3Н5М3Ф in the manufacture of tube blanks of Ø 67±0,1 mm from a copper-nickel alloy of the МНЖ 5-1 brand are carried out. As a result of research “Artemovsk plant for processing of non-ferrous metals and alloys” (Bakhmut, Donetsk region, Ukraine) at an operating temperature of 900–950 ° C, matrices made of steel 4Х3Н5М3Ф (without deformation-forging) showed stability in three times higher than the matrices from steel 3Х3М3Ф made at the enterprise.