SUMMARY

The wear behavior of high strength steels and metal matrix composites was investigated by way of microstructure based multi-scale modeling. The multi-scale modeling and simulation approach enables to establish links between material microstructure and its properties, microstructure and wear performance, as well as to produce methods for understanding and quantifying the conditions the materials are subjected to in component and process loading conditions and environments. Also, transferability of small scale experimental data to component scale can be addressed and design of appropriate material solutions improved in a case-specific and tailored manner.

RESULT

Impact and abrasive wear processes were computationally modeled during the DEMAPP WEAR project. As a result, a toolset was developed for tailoring materials and performing component design for such wear inducing conditions. The main exploitation pathway is the establishment of links and correlations between wear-inducing conditions, micro-mechanisms of wear, and material microstructure. Simulations can be carried out to study any such particular features in detail, as well as to carry out “what-if” like scenarios and sensitivity analyses, e.g. related to the significance of specific characteristics of the material microstructure.


Towards comprehensive control of wear

The multi-scale modeling methodology was developed and applied for five different materials, ranging from wear resistant steels to metal matrix composites and thick wear resistant coatings. For high strength steels, the significance and role of martensite sub-structures was investigated and specific prior austenite grain sub-block structures demonstrated to be of great significance for wear resistance, both with respect to their morphology and orientation distribution. For metal matrix composites and coated systems, the tailoring of their microstructural carbide structures was found to be an exploitable route to address and tailor the wear resistance in a case-specific manner. Various studies into the fundamentals of wear micro-mechanisms were carried out, such as the study of shear slip localization in high strength steels as a result of high rate deformation and impact wear conditions. A key feature of the simulation workflows was consistent linkage to experimental and characterization activities, to yield consistent validation and verification as well as produce models with predictive capabilities.

Examples of a) computational martensite block structure and b) multiscale finite element model for analyzing the microstructural response during an HVPI experiment.

MOTIVATION

The resulting modeling methods enable the simulation of abrasive and impact wear mechanisms utilizing material microstructure as a starting point, and as such enable the study of wear process fundamentals as well as material features dominating the associated material performance.

APPLICATIONS/
IMPACT

The enhanced understanding of the wear phenomena has been the enabling factor in the improvement of the wear resistance of Ruukki’s new steels. For example, the steel compositions and process parameters have been optimized to obtain the desired microstructures and mechanical properties. During the DEMAPP program, the thickness range of the direct quenched Raex steels was expanded up to 80 mm and down to 2 mm.

MAIN CONTACT

Anssi Laukkanen & Kenneth Holmberg, VTT Technical Research Centre of Finland,

Veli-Tapani Kuokkala, Tampere University of Technology, and

Pekka Siitonen, Metso Oyj

PROJECT PARTNERS

Tampere University of Technology, VTT Technical Research Centre of Finland, Metso Oyj, Ruukki Metals Oy

AUTHORS