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<p> Powder Metallurgy (P/M) offers a very efficient method to produce high volume, high throughput steel parts. The two most important property issues affecting P/M steels are: (I) possessing high mechanical properties despite having inherent internal porosity; (2) maintaining very tight dimensional tolerances during processing (sintering). Researchers are continually looking at ways to improve these two properties while keeping costs down. As in wrought and cast steels, in most applications P/M steels are alloyed; in P/M processing, alloys are typically added to Fe + C powder mixes as elemental powders. The entire mix of Fe+ C +elemental alloying additives are then consolidated under high pressure and sintered at high temperatures to strengthen the compact. The current work deals mainly with the the most commonly used alloying additives in P/M steels, Ni and Cu. </p> <p> While it is well-known that Ni and Cu do indeed improve the mechanical performance of steels and do affect the dimensional change of P/M parts in specific ways, for over 50 years the same standard Ni and Cu powders have been used in the industry. With new breakthroughs in the production of extra-fine metal powders (- 1-2 urn) P/M researchers now must examine the effect of particle size of alloying additions on the performance of sintered steels. Prior to the current work, significant documented work investigating the effect of particle size of Ni and Cu on the performance of P/M steels was very limited. </p> <p> The current work examined: (I) Ni powder particle size effects in P/M Ni steels; (2) Ni powder particle size effects in P/M Ni-Cu steels; (3) Ni and Cu powder particle size effects in P/M Ni-Cu-Mo steels. </p> <p> Specific focus was on determining the effects of particle sizes on the dimensional control and mechanical peformance of P/M steels. With both Ni and Cu, the finer the powder addition the better the dimensional control and mechanical performance of the steels. In steels containing both Ni and Cu, finer Ni also improved the distribution and diffusion of Cu. This suggested that there was a significant interaction between Ni and Cu during sintering which could be tailored to improve properties. The effect of changing Ni particle size on overall steel properties was significantly greater than the effect of changing Cu particle size. </p> <p> Mechanistic analyses via optical microscopy, SEM-EDX and E-SEM investigation, dilatometry, and differential thermal analysis were carried out to explain the results. Mathematical models were also developed to show the effect of Ni and Cu particle size on diffusion into the Fe matrix during sintering. </p> / Thesis / Master of Applied Science (MASc)

Powder metals are becoming a popular choice in the automotive and other manufacturing industries because of their ability to meet wide ranging product functional requirements without compromising the performance of the product. They offer various advantages, including weight reduction, near net-shape processing capability, and their ability to be sintered to achieve desired properties in the end-product. However, in order to satisfy the product design requirements during manufacturing, they need to be machined to the required tolerances. Machining of powder metals is quite different to machining of traditional metals because of their specific properties, including porosity. This thesis work deals with the finish machining of powder metal steels in automotive applications, for increased tool-life/reduced tool-wear. Tool-life is affected by a variety of factors such as tool grade selection, tool coating, cutting conditions and tool geometry including cutting edge geometry. This work involves optimization of cutting conditions for plunge cutting and boring operations of automotive powder metal components using PCBN and carbide tools. The cycle time of the process introduces an additional constraint for the optimization model along with the tool-wear criterion. Optimized cutting conditions are achieved for maximum tool-life.

Thesis (Ph.D.)--McMaster University, 2005. / Supervisor: Ken Coley. Includes bibliographical references (leaves 204-211).

To be in line with the Paris Agreement and mitigate average temperature rise to 1.5°C, and to a maximum of 2°C, greenhouse gas emissions will have to be reduced close to zero before mid-century. If these targets are to be reached, rapid and complete decarbonisation of every sector within the global economy is required. Currently, energy-intensive industrial sectors account for more than 30% of global energy use, and are responsible for approximately 50 % of global greenhouse gas emissions, whereas the iron and steel industries have the largest aggregated greenhouse gas emissions globally. Although the steel industry is at the cusp of major climate neutrality transitions, as recent studies have presented opportunities of producing completely fossil-free steel, decarbonising large-scale production processes is a complex query affected by a multitude of internal and external factors. Höganäs AB, as one of the largest powder metal manufacturers in Sweden, has initiated their work towards net-zero emissions in 2045. With production sites in over 18 countries, the company serves as an example of a company in the midst of turning a “hard-to-abate” industry towards being sustainable.  The aim of this study is thus to assess the effects of climate agendas and frameworks, such as the Paris Agreement and the IPCC Report on initiatives and policies on a global, national and regional level within countries where Höganäs AB has its major production facilities. The aim is further to review the effects of climate strategies and targets on the steel and powder metal industry, as well as to monitor the industry’s inclinations towards climate neutrality. The findings of the performed literature study, as well as the conducted qualitative interviews, resulted in a framework regarding how to identify and assess trends within the steel and powder metal industry based on two theoretical perspectives on corporate climate transitions. Through the results, it could be concluded that despite all countries having ratified the Paris Agreement as of January 2021, no country is currently on the path towards reaching the 1.5°C target that is recommended by the IPCC Report and the Paris Agreement. Still, there is a growing demand for low-carbon technology and renewable energy in every country, something that will partly weigh up for both up-scaled industrial production and countries’ increased GDP. Within the industry, an increased number of initiatives and commitments has been launched during the past few years, indicating that questions of climate change and sustainability are being entrenched in the corporate sector. Going forward, indicators to measure continuous improvements to reach net-zero are associated with emission- and energy data, value chain management and industry investments. As technological advancements towards hydrogen, electrification and digitalisation are being upscaled and increasingly tangible, climate neutrality in the PM and steel industry is achievable through a profound and intended climate focus and an increased sense of urgency.