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Disruptive innovation through new tool steels with unique thermo-mechanical performance for material forming applications

Periodic Reporting for period 2 - FASTEEL (Disruptive innovation through new tool steels with unique thermo-mechanical performance formaterial forming applications)

Reporting period: 2017-05-01 to 2018-10-31

The FASTEEL project deals with the upscaling and validation of the new generation of innovative high thermal conductivity tool steels of Rovalma. The main application targets of FASTEEL grades are tools, dies, moulds and inserts for hot forming production processes, especially die casting of light alloys, plastic injection moulding, hot stamping of Advanced High Strength Steels and composite forming. In these processes, the dies fulfil two important functions: (1) shaping of a material into the desired component geometry, (2) being a heat transfer medium. The shaped components are solidified and cooled by extracting the heat previously used to melt (in the case of die casting and plastic injection moulding) or to preheat (in the case of hot stamping) the component material. When the melt or preheated material is introduced into the dies, the heat is removed from the components by the corresponding forming tools. The heat is then transferred through the tool material to the cooling medium inside the cooling lines of the tools. Tool material thus functions as a bridge between the cooling medium and the shaped component inside the die. The flux of heat crossing this bridge is determined by the thermal conductivity (TC) of the tool material. As the rate of heat transfer depends on the TC of the tool material, the low TC of traditionally used tool steels limits the productivity of these hot forming processes and the feasibility of making thinner and more complex components. ROVALMA has invented technology to make tool steels with the required mechanical properties for these tools with very high TC. There is an enormous market potential for these tool steels, however manufacturing of a tool is a costly process and associated with other important requirements such as standardization, conformance control, certification, heat treatment requirements, machinability, weldability, surface treatability, safety instructions for the handling. In addition to the combination of high TC and high mechanical properties, FASTEEL grades feature another innovative feature compared to conventional tool steels, as they are supplied in an easy-to-machine state and ready for precipitation hardening through a single low temperature cycle, or in pre-hardened condition and with the hardness and other mechanical properties adjusted to the typical application requirements of the different forming processes. These features shorten the tool manufacturing time and cost considerably, allow to realize the benefits of a homogenous property distribution throughout the tool, with the corresponding positive impacts on produced component quality and durability of the dies themselves. Thanks to the work carried out, the project objectives have been achieved with success: the FASTEEL grades have been up-scaled, optimized, pilot-tested and are now ready for market launch.
The technical requirements for FASTEEL grades for each target application were defined and the respective validation methods, quality control system and certification types were determined. FASTEEL grades’ mechanical and physical properties were evaluated by well-respected external institutions. Material security data sheets have been elaborated in accordance with applicable national legislations. Guidelines for the production have been prepared to carry out the up-scaling process in the most cost-efficient manner. The up-scaling of the production process has been finalized and material of the different FASTEEL grades was sent to cooperation partners for testing in agreed pilots. The gathered information with regard to the validated properties of the upscaled FASTEEL grades, together with the outstanding results achieved with FASTEEL in service, have given clear evidence of the benefits provided by FASTEEL. The comprehensive dissemination activities undertaken (project website, participation in congresses and fairs, visits to key customers), have created great interest in FASTEEL on the side the diverse stakeholders. Machining, welding and texturizing guidelines have been prepared, as well as recommendations for possible combinations of FASTEEL with surface treatments. Electromagnetic properties of FASTEEL grades have been assessed to dispose of the information required for induction heating methods of moulds used in emerging heat & cool technologies for the advanced forming of composites. The plan for exploitation has been elaborated, and the operational and investor ready business plan and marketing strategy have been defined, and a comprehensive protection of project results has been achieved. The attached imaged provides a graphic summary of FASTEEL properties and benefits.
Material forming processes are directly affected by the global trend for lighter, functional and more complex components. Nowadays, composite forming, plastic injection moulding (PIM), die casting of light alloys (DC) and hot stamping (HS) of Ultra and Advanced High Strength Steels are the major material forming processes, by which light weight components are being produced, and which have the potential to address the challenge of making thinner and complex geometry components. The common point of all these hot work material forming processes is related to the fact that the heat transfer mechanism is controlled by the thermal properties of the tool material, which determines the productivity of the forming process and the feasibility of making thinner and more complex geometry components. Traditionally used hot work tool steels such as EN/DIN 1.2343 (H11, SKD 60) and 1.2344 (H13, SKD 61) have been used because of their good properties at high temperature, indispensable for having an acceptable life time of the die. However, the TC of these tool steels is low, generally between 25-29 W/m·K. Considering the thermo-mechanical load acting on the tool, the tool material must have physical and mechanical properties that stand these loadings. Previous attempts to develop higher TC tool steels led to steels with low hardenability (poor mechanical properties). Hence the use of tool steels of this type are EN-DIN 1.2311/12 or EN-DIN 1.2738 (P20), which have slightly higher TC of 30-35 W/m·K, is limited to some moulds for PIM; they cannot be used for hot forming processes like DC, HT and other PIM that require high fatigue and wear resistance. The FASTEEL grades upscaled and validated in this project have overcome these limitations, enabling significant savings in terms of energy resources, raw materials, equipment and machining costs per produced part. Another important impact is the formability of larger, higher strength, lower weight components with increased geometric complexity enabled by the quick heat diffusion capacity through FASTEEL, leading to a more homogenous cooling of the shaped components and thereby allowing the production of thinner components, without endangering passenger’s safety. Consequently, the FASTEEL technology enables not only resource savings through increased production process productivity and improved component quality, but also the corresponding emission reductions per each saved kilogram of vehicle weight achieved through the use of lighter components. The now available upscaled FASTEEL grades can hence be considered a key-enabling technology to help achieving emission reduction targets agreed by the EU.
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