Melt spinning process for acrylonitrile polymer fiber-three or more stretch stages

In a process for preparing an acrylonitrile polymer fiber wherein a single phase fusion melt of acrylonitrile polymer and water is extruded through a spinnerette directly into a steam-pressurized solidification zone maintained under conditions of saturation, pressure and temperature which control the rate of release of water from the nascent extrudate and maintain the nascent extrudate in a stretchable state and stretching the extrudate while it remains within said solidification zone, the improvement which comprises conducting the stretching in at least three stretch stages, the first stage being conducted at a stretch ratio in the range of about 1.1 to 10 relative to the linear speed of the fusion melt through the spinerette, the second and third stages being conducted at a total stretch ratio greater than that of the first stage and the third and any subsequent stages being conducted at a stretch ratio that reduces steam pressure requirements for fiber relaxation.