P 819 – High-Tec tool elements from ultra high strength steel for agriculture applications
High performance active elements for agricultural machines as plowshares, harrows, and harvester blades are normally made of standard heat-treatable steels, as e.g. 27MnCrB5. As a result, these parts suffer a short working life due to a high degree of abrasion and wear. Therefore, wear parts of farming machinery used for cultivation of soil as plows and heavy-duty harrows often wear out within hours and have to be serviced, replaced, or repaired regularly.
Hence, objective of the research work is the efficient and economic manufacture of high performance active elements (as knives and share e.g.) for agricultural machinery with improved qualities. Central approach is the application of ultra high-strength steels and the use of innovative manufacturing technologies in order to achieve excellent product’s qualities and an efficient and economic manufacturing as well.
Thermal processing is eligible to introduce the desired material’s strength. Due to the high thickness of the evaluated materials, process parameters of conventional press hardening processes can not or limitedly be applied. Hence, the application of suitable process parameters and –strategies has been determined. Further, thermo-mechanical processing has been developed introduce even higher material’s strength in contrast to mere martensitic hardening strategies. In addition, the application of carbide inserts and thermochemical coatings as planar wear protection has been evaluated. As the conventional manufacturing of high performance active elements is characterized by sequential process steps, the integration of these upstream process elements into a comprehensive hot forming operation is eligible to increase the process’s efficiency and economy. Hence, warm shear cutting,punching, and punching with combined forming technologies in order to substitute conventional thermal cutting and machining operations has been evaluated.
The use of ultra high-strength steels as material for agricultural wear parts as shares and knives is very promising as field trial shows. The lifetime increases up to 30% due to the use of the investigated materials. Carbide inserts are applicable to multiply the lifetimes. Further, the economy of thick sheet manufacturing processing has significantly been increased. This compensates possibly higher costs of the steels used. However, the application of ultra high-strength steels and the developed manufacturing techniques in wide field of applications is conceivable.
The research project was carried out at Lehrstuhl für Umformende und Spannende Fertigungstechnik der Universität Paderborn. FOSTA has accompanied the research work and has organized the project funding from the Foundation for Steel Application Research.
Only available in german language.
W. Homberg, T. Rostek