| The effects of tramp elements on the microstructures and mechanical properties of high strength low carbon TRIP aided cold-rolled steel sheets were investigated in the present study. Four kinds of 0.15C-1.5Mn-1.5Si-(Cu, Cr, and Ni) cold-rolled steel sheets were prepared, and microstructural observation and tensile tests were conducted after intercritical annealing and isothermal treatment. The main emphasis has been placed on understanding the effects of tramp elements (Cu, Cr, and Ni) on microstructures, retained austenite volume fractions, and mechanical properties of the cold-rolled steel sheets. The addition of Cu or Cu+Ni resulted in a great increase of the retained austenite volume fraction as well as a discontinuous yielding behavior, and the elongation and the strength-elongation balance were higher than that of the Cr containing cold-rolled steel sheets. The addition of Cr or Cr+Ni showed a dual phase stress-strain curve behavior having high tensile strength up to 1,000 ㎫ and low elongation about 20%. |
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