A $$\phi $$ $$40$$ $$mm$$ job is subjected to orthogonal turning by a $$ + {10^ \circ }$$ rake angle tool at $$500$$ $$rev/min.$$ By direct measurement during the cutting operation, the shear angle was found equal to $${25^ \circ }.$$

The velocity (in $$m/min$$) with which the chip flows on the tool face is

The following data relate to an orthogonal turning process:
$$\,\,\,\,\,\,\,\,\,\,\,$$Back rake angle $$=15deg,$$
$$\,\,\,\,\,\,\,\,\,\,\,$$Width of cut $$=2mm,$$
$$\,\,\,\,\,\,\,\,\,\,\,$$Chip thickness $$=0.4mm,$$
$$\,\,\,\,\,\,\,\,\,\,\,$$Feed rate $$=0.2mm/rev.$$

The shear angle is

The following data relate to an orthogonal turning process:
$$\,\,\,\,\,\,\,\,\,\,\,$$Back rake angle $$=15deg,$$
$$\,\,\,\,\,\,\,\,\,\,\,$$Width of cut $$=2mm,$$
$$\,\,\,\,\,\,\,\,\,\,\,$$Chip thickness $$=0.4mm,$$
$$\,\,\,\,\,\,\,\,\,\,\,$$Feed rate $$=0.2mm/rev.$$

If the cutting force and the thrust force are $$900N$$ and $$810N,$$ the mean strength in $$Mpa$$

In which of the choices given below, the cutting tool materials are placed in the ascending order of permissible cutting speed for machining of steel?