The Ni-Hard alloys are among the most effective materials for applications requiring a high degree of strength、hardness and wear resistance. A further investigation was made of the effect of C、Cr、Si and Mo、B、RE on microstructure and properties in Ni-Hard 4. So that a more stable adjustment was made on the alloy composition. The trans-formation courve (CCT、TTT) was given here, and a prevailed heat treatment technology was obtained to assure the hardenability of thick section castings, and prevent the appearence of defects such as crack. It is found that the formation of pearlite is mainly caused by element segregation, a method was given to prevent to remove it. Comparision with high-chromium cast iron, a systematic research was made on the wear resistance of Ni-Hard 4 in different working environment, several kind of wear testers were employed(reciprocating grooving tester、dry sand rubber wheeel tester、single-pass pendulum impact grooving tester and impact erosion tester). The results show that Ni-Hard 4 have good wear resistance than high-chromium cast iron when impact load are present. Some results of the effect of composition、microstructure and heat treatment of wear resistance was discussed, wear mechanism was inquired.
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