Scientists to find the way to keep steel solid

Study finds way to keep steel solid. Scientists studying how metals are degraded in nuclear fusion reactors say their work could lead to new kinds of steel that are more solid at the high temperatures that led to the collapse of the World Trade Center. Scientists have discovered that microscopic magnetic properties of iron are responsible for the fact that it softens and loses strength at 500C, only about a third of its melting point. The fact that iron softens at temperatures much lower than its melting point is well known and has long been exploited by blacksmiths and ironmongers. But the same property that makes iron easy to work also makes it vulnerable at higher temperatures. Until now though, scientists didn't understand why this happens. According to Dudarev, the softening depends on a so-called phase transition that changes the crystalline structure of the iron. The transition occurs at 911.5C but increasing temperatures affect it gradually and changes to the structure can be detected at 500C. After production, iron contains so-called dislocations where lines of atoms in the crystalline structure finish abruptly and other rows bend around them. The new research shows that these dislocations do not affect the strength of iron at room temperature. However, changes in the crystalline arrangement of atoms at higher temperatures disturb these magnetic properties of atoms leading to a runaway process of dislocation that causes softening. Dudarev, working at the Culham Science Centre in Oxfordshire operated by the UK Atomic Energy Authority, said that the findings provide the basis for developing new kinds of steel ""that systematically withstand load even if the temperature goes to 1,000C"". Such steels could also be used in other high temperature environments such as hydrogen production plants and nuclear fusion plants due to their ability to withstand radiation as well as high temperatures.