DK-SPEC (Canada)

Squaring, a wood transformation process, is an operation which consists of introducing the logs into a squaring machine which then uses sharp tools to cut the wood into pieces with high surface quality. Tool steels used in this process experience significant wear, damaging the wood surface and hence leading to substantial scrape rate. This study investigates the wear resistance of three tool steels specifically designed for wood cutting applications: modified AISI A8, modified steels with 0% and 1% tungsten, and powder metallurgy prepared W360 steel. Furthermore, the influence of a PVD coating on the wear resistance of the three alloys was investigated. ASTM G65 abrasive wear tests were conducted using the dry sand/rubber wheel abrasion test. A methodology using a non-contact 3D measurement system and specialized software was developed, allowing for a thorough quantitative assessment of the wear of these steels. The results revealed that the coated A8mod + 1%W steel exhibits the best resistance among the coated steels. Despite the excellent intrinsic resistance of W360 steel, the coating did not provide a significant improvement for this steel, showing only a 10% reduction in wear. Microstructural analysis revealed that the predominant wear mechanisms were abrasion and impact. The relative performance of each steel was quantified and is reported. Field trials conducted under actual cutting conditions, indicate the superiority of W360 steel in terms of resilience to wear and impacts compared to other tested alloys, while confirming the effectiveness of surface treatments in mitigating material wear. However, A8 steel modified with 1% tungsten exhibits increased wear under coating.

This study is focused on determining the impact of short-time annealing during industrial brazing process. Short-time annealing is commonly used to alleviate residual stresses resulting from the brazing process and represent in this study 30% of the process time. Samples were selected using two designs of experiments with three main parameters which are temperature of brazing, temperature of short-time annealing and time of first cooling for the first, and temperature of brazing for the second. Shear resistance tests allowed to refine the selection of samples for further investigation. EDS views, hardness measurements and residual stress measurements were conducted. From the obtained results, although slight differences were observed in the microstructure, hardness, and residual stresses of the samples, no clear pattern of impacts could be attributed to short-time annealing. In conclusion, this study did not find substantial evidence of short-time annealing having a significant impact on the microstructure, hardness, or residual stresses in the context of industrial brazing for wood cutting tools. Further research could explore other annealing parameters or alternative heat treatment methods to achieve the desired material properties.