Abstract. Electrode composite wire (CW) was used for argon-arc surfacing of a thermalresisting nickel aluminide-based alloy (Ni-Al-Cr-W-Mo-Ta system) on the butt-end surface of the non-water-cooled piercing mandrel. It was shown that multipassing surfacing forms a defect-free deposited metal based on the γ'-Ni 3 Al phase of various structural origins. Using high-temperature sclerometry and thermal fatigue testing methods, the metal deposited with CW containing ultrafine particle of 0.3-0.4 % wt. WC carbide features increased resistance to thermal and force effects at temperatures up to 1200 °С.
IntroductionIt is known that in the temperature range of 1100-1200 °С, the most efficient alloys are heat-resistant γ'-Ni 3 Al phase-based alloys produced by casting with high-gradient directed crystallisation with a specified structure throughout the whole workpiece [1][2][3]. This approach is not always possible or efficient when it is necessary to strengthen the most stressed areas of the metallurgical tools (piercing mandrels, pressing tools). Their intensive wear is due to the metal deformation in temperature-force cycling up to 1200 °С. Such operation conditions are the most common for large non-water-cooled mandrels, piercing the workpieces of difficult-to-form heat-resistant and corrosion-resisting steels and alloys [4,5]. This increases the relevance of the technologically flexible processes of surfacing of such mandrels with γ'-Ni 3 Al-based materials, featuring high deformation resistance of the deposited metal at temperature up to 1200 ºС. One way to increase the strength properties of Ni 3 Al-based metal is microalloying with rare-earth (La, Y, Ce) metals (REM) [6,7]. This makes it possible to stabilise the structure with nanosized (up to 70 nm) endogenous phases due to their low solubility in γ'+γ solid solutions [7]. At the same time, due to their surface activity, REMs decrease the melt surface tension and influence the energy required for nucleation centers, which increases their amount [8]. Such a mechanism can also be employed with refractory thermally stable compounds when introducing them into the weld pool melt in the form of exogenous ultrafine particles [9], as well as with REMs with high surface energy.The objective of this paper is to increase the deposited metal wear resistance under the thermalforce action using CW containing ultrafine components, as well as to study their effect on the structure formation of nickel aluminide γ'-Ni 3 Al-based metal.