Strain Hardening and Uniform Elongation of 1700MPa Grade Maraging Steel

Abstract

Strain-hardening characteristics of an 1700MPa grade maraging steel were analyzed, and the influence of dislocations introduced by martensite transformation, very fine Mo-rich clusters, fine and coarse precipitates and reverted austenite on the strain-hardening rate was examined.(1) The plastic deformation was mainly composed of four fundamental stages with different strain-hardening characteristics, (2) In the solution-treated or low-temperature aged steels, the plastic deformation began with stage I which was chiefly affected by the initial dislocation density and perhaps subsidiarily by the very fine Mo-rich clusters, and was followed by stages III and IV with linear hardening. The strain-hardening rate in stage III was raised by the fine precipitates especially by the dense Mo-rich clusters, The extent of uniform elongation was determined mainly by the strain-hardening characteristics in stage I.(3) In the high-temperature aged steels, stage II with high strain-hardening rate due to coarse precipitates appeared, and the uniform elongation increased largely. The large amount of reverted austenite raised the strain-hardening rate in stage III, but the reverted austenite only slightly increased the uniform elongation.