Several different tool steel grades were deposited on mild steel by the laser-cladding process with coaxial powder feeding. With bidirectional scanning pattern, most of the grades were deposited crack-free with hardness up to 1000 HV without additional preheating. In a 3-body abrasion wear study, the laser clad Ralloy^® WR6 with significant portion of retained austenite exhibited superior abrasive wear resistance compared with the predominantly martensitic tool steel coatings (M2, M4, H13, HS-23, HS-30) and the reference material, Raex^® Ar500 wear resistant steel. The abrasion wear resistance of austenitic–martensitic WR6 tool steel was further enhanced by the external addition of 20% volume percentage of relatively large (45–106 µm) vanadium carbides. In single point scratch tests, predominantly martensitic tool steels outperformed austenitic–martensitic tool steels and wear resistant steel. The differences in wear performances were explained by different wear mechanisms and types of contact between the abrasive and the surface.

The general specification of nickel-base alloy 625 is quite permissible allowing relatively large variations in chemical composition. In directed energy deposition processes including laser cladding and additive manufacturing, the powder plays a key role in the properties of final products. Therefore, it is important to select the highest-quality powder. Several commercially available alloy 625 powders were characterized and deposited on mild steel by the laser cladding process using a coaxial powder feeding method and a single bead. Clad layer characterization consisted of determination of dilution and quantification of hot cracks. The results showed that powders containing the lowest amount of impurity elements (S, P, B) were the most resistant to hot cracking. Ti and Al were beneficial if impurity element contents were high.

: Cold metal transfer (CMT) welding technique was used in the manufacturing of hypoeutectic carbide-type Co-based Stellite 12 hardfacings on martensitic stainless steel. It was discovered that the CMT process is capable of producing relatively thick (> 2.5 mm) low diluted single-layer coatings with cored Stellite 12 wire without cracks and pores. These coatings were investigated using microscopy (optical and scanning electron microscopy), X-ray diffraction, and hardness measurements. The high melting point chromium and tungsten particles inside the cored wire were relatively large and therefore remained unmelted in the clad layers. Self-mated sliding wear tests were performed using a pin-on-disc tribometer at room temperature and at 300 °C to determine the wear resistance and friction of the coatings. The coefficients of friction were relatively similar (~ 0.35) at both temperatures. Differences were exhibited in the ~ 40% greater loss of material at high temperature. The wear performance of the CMT clad Stellite 12 coatings did not, however, reach the wear performance of self-mated laser clad Stellite 6 reference material. CMT hardfacing was finally successfully demonstrated on a ring-shaped component.

Fusion-bonded and low-diluted overlay welded coatings are frequently very thick (>1mm). High-speed laser cladding is a novel process capable of producing thin fusion-bonded and low-diluted coatings with high coverage rates and low heat input. In this study, for the first time, high-speed laser cladding was used to fabricate relatively thin Ni-based coatings reinforced with chromium carbides onto low-alloy structural and quenched and tempered steels. Obtained coatings were characterized with X-ray diffraction (XRD), optical (OM), and scanning electron microscopy (SEM), as well as electron backscatter diffraction (EBSD). Mechanical and wear properties were tested with Vickers microhardness measurements and three-body dry-sand rubber wheel abrasion tests (RWAT). It was shown that high-speed laser cladding produces 0.2–0.3-mm-thick coatings, which consist of ultrafine-substructured hypereutectic M₇C₃ structures reinforced with coarser primary Cr₃C₂ particles. Coatings with hardness up to 1300 HV_0.05 exhibited high wear resistance in low-stress three-body abrasion. Coatings developed can be used as alternatives for hard-chrome plated coatings.

A laser clad and machined cylindrical structural steel rod was fatigue tested under four-point bending load. The resulting fracture could be tracked back to a spherical surface pore in the Co-based coating. Due to an oxide inclusion, the pore was not identified by dye penetrant inspection. Two circular buckling strain patterns that were detected beside the pore at the surfaces after fracture confirm local plastic deformation prior to crack initiation. In order to calculate the stress field around the surface pore, linear elastic finite element analysis was carried out. For four-point bending load, a surface pore generally exceeds the maximum stress of a smooth rod as long as the pore is located within an azimuthal angle of ±55°, which was the case for the presented as well as for another pore initiated sample.