PROJECT DESCRIPTION
BACKGROUND
The production process for high-performance steel components for the automotive industry has a considerable impact on the environment and on human health that could be alleviated with more efficient use of raw materials and energy, and reductions in waste chemicals and greenhouse gas emissions. High-performance steel components, such as gears, are currently produced by a machining technology, mainly due to high requirements in terms of mechanical properties and dimensional stability. The Powder Metallurgy (PM) technology is a sustainable manufacturing process recognised as a green technology and the high mechanical and dimensional requirements above-mentioned could also be theoretically met by means of an innovative Die Wall Lubrication (DWL) compaction stage, in combination with high-temperature vacuum sintering and thermochemical treatment. The DWL compaction process is currently used only in a limited number of applications. It is currently not exploited at an industrial level due to the difficulties of planning, managing and monitoring the productive process.
OBJECTIVES
The aim of the LIFE 4GreenSteel project was to demonstrate the feasibility of replacing the traditional energy-intensive and material-consuming machining of wrought metals with a new and innovative High Density Powder Metallurgy (HDPM) technology for the manufacturing of widely-used high-performance steel components, particularly gears for the automotive market.
Specific technical objectives were to:
- Develop an effective pressing system, operating with the DWL technique, to produce sintered steel parts that have a density greater than 7.3 g/cc and high dimensional stability;
- Tailoring the high-temperature vacuum sintering stage and development of a reliable case-hardened profile of PM steel by means of the thermochemical treatment Low Pressure Carburising (LPC);
- Use a chemical composition for steel avoiding harmful alloying elements (nickel), such as nickel, or alloying elements that make the recycling process difficult and ineffective, such as copper;
- Reduce by more than 70% the lubricant premixed with metal powder, so eliminating the burning stage, increasing energy efficiency and solving related emission problems; and
- Achieve energy and material saving through the innovative HDPM technology, which has a very high coefficient of material use (95%) and therefore minimises energy input.
The project actions expected to contribute to the implementation of the Circular Economy Action Plan, the Roadmap to a Resource Efficient Europe, the Directive on Energy end-use efficiency and energy services, and Decision (406/2009/CE) on Energy Efficiency. Furthermore, LIFE 4GreenSteel is relevant to EU policy on sustainable growth and will also provide European enterprises with tools to enhance their competitiveness.
RESULTS
The LIFE 4GreenSteel project beneficiaries demonstrated the feasibility of replacing the traditional energy-intensive and material-consuming machining of wrought metals with innovative High Density Powder Metallurgy (HDPM) technology for the manufacturing of widely-used high-performance steel components, in particular gears.
Main project outcomes were:
- The definition, production and testing of a new lubricant.
- The development, manufacture and testing of a press prototype, with an integrated Die Wall Lubrication (DWL) system.
- The successful integration of a reliable lubricant deposition system, comprising a robotic spray gun, in the press prototype. Thousands of samples of different geometries have been produced using the DWL technology.
- The successful validation of the HDPM compaction system, even with samples having complex geometries, for densities up to 7.70 g/cc.
- The alloy design, based on adding silicon and manganese to steel powders, provided good technical results in term of compressibility and hardenability.
- All target mechanical properties reached or exceeded.
- The production and testing of a set of spur gears with excellent results (e.g. high density, good mechanical properties), demonstrating that sintered spur gears can replace the forged ones obtained by the traditional machining process.
- · Dissemination and networking activities.
- · Monitoring activities and LCA showed that the project’s spur gears were made with a significant reduction in environmental impact.
Direct environmental benefits are related to the saving of machining emulsions, energy, the elimination of ferrous metal filings, the substitution of chemical substances with non-chemical ones, and avoidance of CO2 emissions in the production of spur gears.
As regards policy, the project contributed to the implementation of the EU Thematic Strategy on the Sustainable Use of Natural Resources, as the project reduced the use of raw materials by 66% compared to traditional machining technology; the Energy Efficiency Directive, due to energy savings of 56.4% compared to traditional machining in an energy-intensive sector; the Waste Framework Directive, by reducing waste thanks to easier recovery of steel alloys and the recycling of by-products; and the Integrated Pollution Prevention and Control (IPPC) Directive. It also supports the objectives of climate change policy and the European Green Deal.
The new process aligns with the principles of a greener and more competitive European industry. It is expected to be used as the basis for the development of Best Available Techniques (BAT) within the IPPC Directive. The beneficiaries also identified some BREFs for energy efficiency, ferrous metals, and iron and steel production.
