High–temperature sintering of a hypereutectoid steel to theoretical density

By using a hypereutectoid steel which develops a liquid phase during sintering above 1050°C the theoretical density can be achieved by a special high temperature sintering process. The limiting problem is the formation of carbon monoxide during the sintering process. If the carbon monoxide cannot escape due to closed porosity, further densification by rearrangement and solution reprecipitation cannot occur. The stress produced by the carbon monoxide in the pores is up to 2.7 MPa. So it is possible that there is an enlargement of the pores during sintering instead of pore shrinkage. An optimized densification to theoretical density can be achieved by a presintering process and low green density. The main sintering process lasts only 20 min, so low production costs are guaranteed. The alloy has excellent wear properties and high hardness.