Factors Influencing the Machinability of Micro-Alloyed and Low Alloy Steels

SummaryThere is considerable interest in the use ot micro-alloyed steels which develop tensile strengths of up to 1100 N/mm2 directly on air cooling from the forging press. Although the elimination of heat treatment will reduce the forging costs, the total cost savings are also dependent upon machining. In this paper the machinability of micro-alloyed steels is compared with that of the low alloy steels they are designed to replace in applications such as crankshafts.It is shown that the machining characteristics of micro-alloyed steel are different to those of low alloy steels when machining with high speed steel. The maximum cutting speeds are dependent upon composition, mechanical properties, heat treatment and microstructure.