Hydrothermal ageing of jute-glass fibre hybrid composites: an acousto-ultrasonic study
Studies of damage under hydrothermal ageing incurred by random fibre glass-reinforced laminates and jute-glass fibre hybrid composites have been carried out using an acoustoultrasonic technique. It is shown that the “stress wave factor” is a sensitive indicator of flexural strength reduction due to hydrothermal effects in both these composites. The incorporation of jute into glass fibre composites brings about a reduction in the rate of degradation of these composites. The treatment of jute with a silane coupling agent marginally improves the strength properties of the hybrids.
Influences of conventional heat treatment and double-fined treatment on structure and properties of cold-punching die made of GCr15 steel were compared. The results show that its crystal and carbonization are fined and dislocated martensite become more after double-fined treatment; at the same time, there are more sheet-retained austernite in lathy martensite and around sheet martensite; broken-orifice changes from definitely cleavage brittleness fracture to definitely cleavage tenacity fracture. Double-fined treatment can effectively improve strength and toughness of GCr15 steel,accordingly increase service life of cold-punching die made of the steel.