Comparison of mechanical properties of Fe-1•75Ni-0•5Mo-1•5Cu-0•4C steels made from PIM and press and sinter processes

Powder injection moulding (PIM) is a relatively new process and only a few alloy standards have been recognised. To further promote the application of this technology, new alloys with competitive mechanical properties need to be developed. Fe-1.75Ni-0.5Mo-1.5Cu-xC is one of the compositions widely used in the conventional powder metallurgy industry in making press and sinter parts. To benefit from the excellent mechanical properties and the accumulated knowledge of this alloy system, the same composition was employed in this study to make powder injection moulded compacts with the expectation that even better mechanical properties would be attained. The results obtained on the compacts sintered at 1200degreesC for I It showed a tensile strength, hardness, and elongation of 685 MPa, 91 HRB, and 7.5% respectively. With heat treatment, the tensile strength and hardness increased to 1530 MPa and 52 HRC, respectively. However, the elongation decreased to less than 1.0%. These properties are better than those of the press and sinter counterparts owing to higher sintered density, finer grain size, and more homogeneous microstructure. PM/0976 The authors (kshwang@ccms.ntu.edu.tw) are at the Institute of Materials Science and Engineering, National Taiwan University, No. 1, Roosevelt Rd., Sec. 4, Taipei 106, Taiwan. Manuscript received 21 August 2001: accepted 23 January 2002. (C) 2002 IoM Communications Ltd.