Effect of tempering process on elasticity and hardness of knitting needles

The influences of different tempering temperatures and tempering time on the elasticity and hardness of knitting needles were studied.The results showed that tempering temperature has an obvious effect on surface hardness of knitting needles.The surface hardness lowers significantly along with tempering temperature rise.When the tempering time is over 60 minutes,surface hardness varies little at the same testing tempering temperature.And the elasticity of knitting needles is mainly influenced by tempering time.When tempering time is less than 60 minutes,the residual deformation value decreases greatly along with temperature rising.At the same time,the residual deformation value changes little and maintains a small value when tempering temperature is higher than 220℃and tempering time is over 60 minutes.The needles can be rendered not only good elasticity,but also high hardness(HV650 above) by an appropriate and plentiful low-temperature tempering process.