Effect of strain rate on the compressive strength and texture of maraging steel grade 250

Abstract

The present study demonstrates the effect of strain rates (in terms of cross head velocities of 0.1, 0.5 and 1 mm/min) during uniaxial compression test of cold rolled and annealed maraging steel (grade 250) on microstructure, texture and mechanical properties. The texture developed at lowest (0.1 mm/min) and highest (1 mm/min) strain rate facilitates the grains of the microstructure to take the equiaxed shape and bring some degree of uniformity as compared to the grains of starting (cold rolled and annealed) material. At intermediate (0.5 mm/min) strain rate the grains reorient towards the starting texture which provides a similarity in the microstructure of this and starting materials. The hardness and compressive strength at 15% total true strain of the alloy increases with increase in strain rates during the compression test. The role of texture in strengthening of compressed samples deformed with different strain rates as compared to the starting sample has been explained by the near Goss recrystallization component ((111) [1-1 0 ]) which is present in the starting material and remains absent in all the compressed samples. The (111)-fibre formation is observed to be an important phenomenon in this alloy. The (111)-fibre is strengthened in the starting material and the material compressed with 0.5 mm/min. The intensity of (111)-fibre becomes weaker for the samples compressed with lowest (0.1 mm/min) and highest (1 mm/min) strain rates and results in improved microstructure of the alloy.