Selected Properties of Hardfacing Layers Created by PTA Technology

Abstract

The paper presents research results on the quality of hardfacing layers made during the renovation of unheated mold surfaces designed for injection of aluminum alloys using the plasma transferred arc (PTA) technology. As mold material, the medium alloy steel X38CrMoV5-1 (H11) was used. For the formation of functional layers, three types of additives in the form of powder were applied: two types on an iron basis with the designation HSS 23 and HSS 30 and one type on a nickel basis with the designation DEW Nibasit 625-P. The hardfacing layers were made on a 120 × 350 × 50 mm plate in two layers on the plasma hardfacing machine PPC 250 R6. The quality of the layers was evaluated by means of nondestructive and destructive tests. The surface integrity of the layers was assessed using visual and capillary tests. The samples passed these tests. The impact of the parameters used and the mixing of the hardfacing metal with base material, as well as the structure analysis, were assessed by means of light and electron microscopy (SEM). The chemical composition of the elements was determined by energy-dispersive X-ray spectroscopy (EDX) analysis using a SEM microscope. The hardness of the individual layers was evaluated. Since, during operation, molds are subjected to significant wear due to friction, the friction coefficients for selected temperatures were determined by the equipment for the evaluation of tribology properties. Based on the experiments conducted, all three types of additives can be used for renovation. However, from a tribology perspective, the additive DEW Nibasit 625-P on a nickel alloy basis is recommended for renovation.

Research on the Tribological Properties of a New Generation of Multi-Layer Nanostructured PVD Coatings for Increasing the Technological Lifetime of Moulds

“…The prerequisite is to continuously monitor the condition of the injection mould, which is subject to complex wear processes as the number of castings increases. The dominant wear mechanisms of mould parts and cores are the following: thermomechanical cyclic loading [1], dissolution of mould metal in aluminium [2,3], mechanical adhesive erosive cavitation wear, chemical soldering [4], aluminium buildup on mould wall, thermal fatigue, etc. [5,6].…”

“…In order to achieve a surface layer with different properties to the base material, it is necessary to clad the original material using two or three layers, since the first layer shows a mixing with the BM (basic material) of about 50%, the second layer less so, and the third layer presents only the properties of the additive material [2]. Brezinova et al, in [1], experimented with two-layer plasma transferred arc (PTA) technology cladding but also with three-layer GTAW cladding or disk laser cladding, CMT cladding, MIG pulse, or TopTIG technology. Many of these technologies have a low heat input and are suitable for local repairs of small cross-sections on the mould or core.…”

Determination of the Effect of Heat Input during Laser Welding on the Magnitude of Residual Stresses in the Refurbishment of Al Alloy Casting

“…The chosen CSP parameters with the used additive material allowed for the creation of high-quality coating layers. Vinas et al [3] carried out an investigation into the possibility of applying surfacing using PTA technology by employing a plasma beam, whereby the quality of the surfacing was satisfactory and there was minimal thermal effect on the substrate surface. A similar effect occurred in the subsurface areas presented in the studies conducted by [4,5] who applied progressive laser control minimizing the heat input in the fabrication of the overlays.…”

Microstructure and Abrasive Wear Resistance of Metal Matrix Composite Coatings Deposited on Steel Grade AISI 4715 by Powder Plasma Transferred Arc Welding Part 2. Mechanical and Structural Properties of a Nickel-Based Alloy Surface Layer Reinforced with Particles of Tungsten Carbide and Synthetic Metal–Diamond Composite

“…Most plasma cladding applications involve the use of a powder filler material enabling the obtainment of deposited layers characterised by various chemical compositions, structure and properties [ 1 , 2 ]. In deposited layers that have the structure of composite materials (used to improve the abrasive wear resistance of drilling tools or machinery), the matrix is usually composed of cobalt, nickel or iron-based alloys containing particles of high-melting phases, e.g., carbides of transition metals found in groups IVB–VIB of the periodic table [ 3 , 4 ].…”