Effect of Hardening Treatment on Strength Characteristics of SUS631 Stainless Steel Foil

In order to clarify the effect of hardening treatment on the strength characteristics of foil specimen of SUS 631 stainless steel (thickness : 0.05 mm), various hardening treatments were done to the foil specimen which solution heat treatment was applied at 1313 K for 2 sec (STF material called here). The strength and the hardness of the foil specimens were measured on STF material and hardening treatmented materials by a tensile test and a micro-vickers hardness test. The fracture surfaces of the foils were also observed by SEM. The main results obtained are summarized as follows. (1) Compared with usual hardening treatment method which is"conditioning of austenite +ageing treatment"for a common SUS 631 steel, ageing hardening treatment was appropriate hardening treatment method for the SUS 631 steel foil. Necessary strength, hardness and toughness could be obtained by selecting a suitable ageing condition. (2) From these experimental results, it was shown that precipitation strengthening micromechanism which resulted from ageing hardening treatment could produce a great effect strength characteristics of the steel foils. (3) The tensile fracture patterns of the materials differed with ageing temperature.