The meaning and consequences of ultrafine grain size in steels
The grain refinement of structural steels is used for four principal purposes:to increase the yield strength,the increase ultimate tensile strength,to lower the ductile-brittle transition or to improve resistance to aggressive environments.Each of these benefits is governed by an equation of the Hall-Petch type.However,the coefficients that rule the equation and the meaning of the effective grain size that appears in it are different for each type of behavior.These differences reflect the fundamental mechanisms that are involved in each behavior,and have the consequence that different ways of accomplishing grain refinement can have very different effects on the balance of properties that is achieved.Recent work on the microstructures of martensite and hainite has generated new information that clarifies these microstructures in important respects.The present paper reviews these results,shows how their microstmctural implications can be explained from the need to accommodate the transformation strain,and discusses their implications for the effective grain size and the microstructural control of properties.
grain refinement ductile-brittle transition Hall-Petch martensite transformation strain
J W Morris Jr.
Dept.of Materials Science and Engineering,University of California,Berkeley,CA 94720,USA
国际会议
上海
英文
242-246
2008-09-26（万方平台首次上网日期，不代表论文的发表时间）