Paper Title
Enhanced Fracture Toughness And Strength For Cold Worked Austenite Stainless Steels Using A Surface Cracking Processes At Low Temperatures

Abstract
Higher strength and toughness are the key requirements of steels for use in the various structural applications such as cryogenics field, aircrafts, buildings, and heavy machineries, in order to satisfy the increasing demands of reliability, durability and safety. Especially, it requires the material with good mechanical properties for use in severe environments such as cryogenics field because material characteristics are significantly degraded and changed at low temperatures. Generally, austenitic stainless steel with face centered cubic (FCC) structure used as low temperature materials because they have no brittle fracture at very low temperature. Cold work is a typical method used for strengthening steels, and it results in unfavorable materials embrittlement with ductility and fracture toughness reduction. In contrast to the fact, we developed a new technique based on surface cracking processes to overcome the degradation of mechanical properties at low temperatures. This method intentionally makes surface-cracks on the cold worked austenite stainless steels and leads to significant increase of their fracture toughness and strength at low temperature in contrast to typical material behaviors. This surface cracking process intentionally induced surface-cracks in cold worked austenite stainless steels leads to significant increases in fracture toughness at low temperatures due to distribution of stress at surface-cracks tip. Keywords - Fracture toughness, Strength, Cold work, Surface cracking process, Low temperatures, austenite stainless steels.