Influence of Preheating Temperature on Structural and Mechanical Properties of a Laser-Welded MMC Cobalt Based Coating Reinforced by TiC and PCD Particles

Abstract

This article presents research on the structural and mechanical properties of an innovative metal matrix composite (MMC) coating designed for use in conditions of intense metal-mineral abrasive wear. The layer, which is intended to protect the working surface of drilling tools used in the oil and natural gas extraction sector, was padded using the multi-run technique on a sheet made of AISI 4715 low-alloy structural steel by Laser Direct Metal Deposition (LDMD) using a high-power fiber laser (FL). An innovative cobalt alloy matrix powder with a ceramic reinforcement of crushed titanium carbide (TiC) and tungsten-coated synthetic polycrystalline diamond (PCD) was used as the surfacing material. The influence of the preheating temperature of the base material on the susceptibility to cracking and abrasive wear of the composite coating was assessed. The structural properties of the coating were characterized by using methods such as optical microscopy, scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffraction analysis (XRD). The mechanical properties of the hardfaced coating were assessed on the basis of the results of a metal-mineral abrasive wear resistance test, hardness measurement, and the observation of the abrasion area with a scanning laser microscope. The results of laboratory tests showed a slight dissolution of the tungsten coating protecting the synthetic PCD particles and the transfer of its components into the metallic matrix of the composite. Moreover, it was proved that an increase in the preheating temperature of the base material prior to welding has a positive effect on reducing the susceptibility of the coating to cracking, reducing the porosity of the metal deposit and increasing the resistance to abrasive wear.

Characterization of a New High Abrasion and Erosion Resistance Iron-Based Alloy for Pta Hardfacing

“…Under the conditions of the experiment, the wear-resistant steel had the lowest value of relative abrasive wear resistance. 1.4617 185.7300 1.00 D1 1) 0.1019 13.4610 13.80 D2 2) 0.1189 15.7067 11.83 Notes: 1) non-heat treated sample, 2) heat treated sample, density of coating: 7.57 (g/cm 3 ); density of AR 400 steel: 7.86 (g/cm 3 ), 3) abrasive wear resistance relative to AR 400 steel plate.…”

“…Erosion rate (mg/min) = mass loss (mg) : time plot (min), Erosion value (mm 3 /g) = volume loss of specimen (mm 3 ) : total mass of abrasive particles (g). Erosion conditions: velocity -70 ± 2 (m/s), erodent impact angle 30°, temperature 20 °C, erodent -Al2O3 of nominal dimension -50 (µm), feed rate -2.0 ± 0.5 (g/min), 3) erosion wear resistance relative to AR 400 steel plate.…”

“…Improving the wear resistance parts of machnines and devices operated under high friction conditions, shock loading, high pressures combined with agrressive corrosive environment in elevated temperatures has been a problem for surface engineering for many years [1][2][3][4][5]. Produced wear-resistant steels (abrasionresistant steels, e.g.…”

High-Power Diode Laser Surface Transformation Hardening of Ferrous Alloys

“…The suppression of the martensitic transformation under non-equilibrium cooling conditions has been reported in several works on the casting and surface treatment of different cast iron grades [ 25 , 26 ]. It indicates that, from the point of view of the maximum surface hardness, the lower traverse speeds, ensuring lower values of the cooling rate, are beneficial in producing more wear-resistant layers [ 27 , 28 ]. On the other hand, to avoid surface melting with increasing power density, the elevation of traverse speed is required.…”