It is the aim of this paper to report on experimental study on highly effective method of annealing stainless steel plate to give it proper tension as spring material. Hereunder are summarized the results of our study.
(1) The stainless steel plate is to be annealed in the following method. Its tension is to be first reduced to 30% by cold rolling, and then the plate is to be annealed at 400-650°C of temperature in non-oxidative atmosphere, under tension not exceeding 20% of tensile strength.
(2) The springs made of stainless steel processed in the above mentioned method have about twice as much strength in fatigue strength and spring limit as copper alloyed springs, and the steel thus annealed, being productive of high resilient mechanism, is fit for production of all varieties of springs.
(3) The passivation of stainless steel treated in the above mentioned procedure is to be made in solution of 30% HNO 3+1% HF at about 30°C temperature.