TUTCRIS

Tool steels are a class of complex carbon and alloy steels that are widely available as powders over a wide compositional range. In this work, several different tool steel grades were deposited on mild steel by the laser cladding process using a continuous wave 4.4 kW Nd:YAG laser in combination with a coaxial powder feeding technique. With bidirectional scanning pattern, most of the grades were deposited crack-free with hardness up to 1000 HV without additional preheating. A comparative study of 3-body abrasion and single point scratch wear behaviour was conducted on the obtained coatings. 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 fully 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, fully martensitic tool steels outperformed austenitic-martensitic tool steels and Raex Ar500 wear resistant steel. The differences in wear performances were explained by different wear mechanisms and types of contact between the abrasive and the surface. These results show the potential of laser cladding in depositing hard and wear resistant tool steel coatings on easier to fabricate and less expensive base materials or remanufacturing of wear resistant steel grades for enhancing the service life of various components. Examples of such components are, for instance, rock and ground drilling bits in mining and construction and various blades and knives in pulp & paper industries.