As shown in the table, the mechanical properties of gray cast iron poured in two different heats are shown.
It can be seen from the table that the tensile strength of gray cast iron alloyed with multi-element alloy additive is basically the same as that of gray cast iron alloyed with copper (only 2.6%), but the Brinell hardness and microhardness of gray cast iron alloyed with multi-element alloy additive are slightly higher than that of copper alloyed gray cast iron, which may be due to the different composition of raw materials melted in the two furnaces, At the same time, the type and quantity of inclusions in gray cast iron will also have an impact on the properties of gray cast iron. Only in terms of tensile strength, multi-element alloy additives have successfully replaced copper.
When the rotating speed and feed rate are constant, the cutting length of the cutting edge for cutting each sample remains unchanged at 1000 mm. The cutting resistance in three directions with different cutting depths is shown in Figures 1, 2 and 3.
It can be seen from the figure that under the three cutting depths, the cutting resistance in three directions of cutting copper alloyed gray iron castings is large, while the cutting resistance in three directions of cutting multi alloy additive alloyed gray iron castings is small. Compared with copper alloying, the main cutting force is reduced by 20.2%, 13% and 15.8% respectively. The reduction of cutting force means that the cutting resistance of the tool is reduced in the cutting process, the tool wear is reduced, the workpiece is easy to be cut, and the machining performance is better. Therefore, the cutting performance of gray iron castings alloyed with multi alloy additives is better than that of gray iron castings alloyed with copper. The tensile strength of gray iron castings is the same (only 2.6% difference), but its machinability is not necessarily the same (at least 13% difference).
It is proved that the uneven structure of the material is an important reason for the decline of machinability. Two kinds of cast iron were measured at 20 mm × The microhardness distribution of pearlite matrix on 20 mm section is shown in table 4-3. It can be seen from the data in table 4-3 that the micro hardness of gray cast iron alloyed with multi-element alloy additives is higher than that of gray cast iron alloyed with Cu. The microhardness deviation is basically the same, indicating that the matrix structure uniformity of the two kinds of gray cast iron is the same, but the machinability of gray cast iron treated with multi-element alloy additives is much better than that of copper alloying. From the test, the machinability of gray cast iron can not be quantified from the structure uniformity.