Research On The Strengthening And Toughening Mechanism Of Nb Micro-alloyed Steel

In recent years, domestic and foreign all devote themselves to developing new high strength micro-alloy steel, because Nb can enhance the strengthening and to be allowed to enhance the toughening, as well as its price superiority, caused the very many applications domain took the niobium is the first choice when the micro-alloy design. The strengthening and toughening of steel is one kind of technology which optimizes the steel strengthening and the toughening mechanics performance synthesis, in prearranges under the condition, through the certain ways, causes its organization shape, the microscopic organization and so on to have the advantageous change, achieved the goal of improving mechanics performance such as strengthening and toughening. Therefore studies discovers the microscopic organizational structure and the strengthening and toughening mechanics intrinsic relations, as well as steel strengthening rationale, thus corresponding obtains its universal law and the mathematical model, it is very important in micro-alloy steel research.This article mainly is by 20MnSiNb took the research object, and other tests researcher's empirical formula based on the strengthening and the microscopic organization's relations, through to the strengthening and toughening of Nb ability in grains refining strengthening, precipitation strengthening and solution strengthening three main strengthened ways the component model computation, finally determined most approaches this research condition the strength calculation formula, and calculates the contrast to these three strengthened way to the always strengthened effect contribution proportion.The results show that, the steel strengthening and toughening both are decided by the steel microscopic structure shape. The strengthening and toughening mechanism of 20MnSiNb steel mainly is the grains refining strengthening, only has the grains refining strengthening can enhances the intensity and improve toughness, therefore it is the most important strengthened way in the steel. The proportion of the grains refining strengthening accounts for the yield strength probably is about 50%, but the precipitation strengthening accounts for the yield strength probably is 7%- 9%, the solution strengthening is 22% - 25%.