Influence of matrix structure on the abrasion wear resistance and toughness of a hot isostatic pressed white iron matrix
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I.
INTRODUCTION
ALLOY white cast irons are the most widely used materials in conditions where resistance against mineral abrasives is required. The exceptional abrasion wear resistance of these materials is attributed to the presence of a high amount of M7C3 eutectic carbides in their structure. However, their toughness is very poor. Thus, their use tends to be restricted to applications where resistance to fracture is not critical. Recent investigations[2–7] have indicated that careful alloy selection and production practices, together with appropriate heat treatment procedures, tend to decline the discrepancy in the fracture properties of these materials, which may result in a wider utilization of alloy white irons. In their previous work,[1] the present authors studied the wear resistance of a powder metallurgical high-Cr white iron reinforced with different amounts of TiC particles. The powder metallurgical routes in the materials production, and particularly the hot isostatic pressing technique, result in more homogeneous materials, which improves the fracture properties. This aspect is important for materials which are prone to segregations, such as highly alloyed steels and white irons.[8,9,10] The earlier work of the authors[1] has demonstrated that high wear resistance against the action of quartz particles can be achieved in a hot isostatic pressed
(hipped) high-Cr white iron by incorporating a relatively small amount of fine ceramic reinforcements. Besides the effects of the reinforcement volume fraction and size on the mechanical properties of composite materials, the structure of the matrix has also a key role.[11,12] Thus, the influence of different heat treatment procedures and the resulting variations in the matrix structure of the composite need careful investigation. Previous studies[2,4,7] in alloy white cast irons have demonstrated that different structures resulting from different heat treatment procedures affect the mechanical properties of the materials to a great extent. In the present work, the influence of the structure of the matrix on the abrasion wear resistance and impact toughness of the hipped white iron-TiC composite was studied in a material with a constant amount of reinforcements. The results for the composite were compared to those of the unreinforced alloy and also to the results reported in the literature for commercial white cast irons. Finally, a comparison between the wear resistance of the composite and two of the most abrasion resistant ferroalloy materials was done in order to assess the potentials of the newly examined material.
II.
EXPERIMENTAL PROCEDURE
A. Test Materials E. PAGOUNIS, Research Scientist, and V.K. LINDROOS, Professor, are with the Laboratory of Physical Metallurgy and Materials Science, Helsinki University of Technology, 02150 Espoo, Finland. M. TALVITIE, Product Manager, is with Rauma Materials Technology Oy, 33101 Tampere, Finland. Manuscript submitted January 17, 1996. METALLURGICAL AND MATERIALS TRANSACTIONS A
A high-Cr white iron (gas atomiz
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