Abstract: Textured yarns which can be processed for example by deep-drawing into irreversibly highly formable woven or knitted fabrics and a process for their preparation are described. These yarns have degrees of elasticity of below 50% and contain at least as carrier component undrawn but partially oriented polyester filaments which have been improved by a heat treatment in their flow stress.

Abstract: A yarn component containing at least one filament is prepared by:selecting at least one partially oriented, undrawn synthetic filament having a birefringence of at least 20.times.10.sup.-3 and an elongation at break of 70-200%, andsubjecting the thus-selected filament or filaments to a heat treatment at 100.degree.-180.degree. C. under tension. The resulting yarn component has a degree of elasticity under a load of 5 cN/tex of less than 50%, which causes the yarn to be especially well suited for use in formable sheet structures.

Abstract: A textile sheet structure which is irreversibly highly deformable is prepared by weaving or knitting a yarn which has a degree of elasticity under a load of 5 cN/tex of less than 50% and which consists at least in part of partially oriented, undrawn synthetic filaments which have birefringence values above 20.times.10.sup.-3, elongations at break between 70 and 200% and flow stresses of at least 6 cN/tex, which have been produced by high-speed spinning and are then subjected to a heat treatment under stress at temperatures between 100.degree. and 180.degree. C.