Influence of Mechanical Deformation and Annealing on Kinetics of Martensite in a Stainless Steel

Abstract

An attempt has been made to understand the kinetics concerning the manufacturing schedule of high strength 304 stainless steel comprising formation of strain-induced a 0 martensite in the course of cold rolling (25%) at 0 C and its reversion during annealing in the temperature range of 300-800 C for 1 h. Increase in reversion with increasing annealing temperature without any perceptible grain growth up to 800 C has been demonstrated by the microstructural investigation. X-ray diffraction analysis has revealed that the 25% cold rolling has resulted in the formation of 20% deformation induced martensite which after annealing at 800 C has been reduced to 8%. Different stages of reversion behaviour have been envisaged by carrying out differential scanning calorimetry. Activation energies of the reactions involved during reversion have been determined by Kissinger method. Results are compared and found to be in good agreement with the published data.

Process Simplification of Multi-Stage Forging for the Outer Race of a CV Joint

“…From Fig. 3(a), the tensile test results show that the spheroidizing heat treatment leads to an increase in the elongation, and a decrease in the yield and the tensile strengths [1,18]. Based on these experimental results, the stress-strain relationship, with the work-hardening model of the with a diameter of 48.0 mm and height of 100.0 mm.…”

Effect of Thermal Charging of Hydrogen on the Microstructure of Metastable Austenitic Stainless Steel

“…Above a certain temperature, the reverse transformation sets in when martensite transforms back to austenite . The reverse transformation temperature is a function of the extent of deformation and has been reported at temperatures starting from 300 °C . The solubility of hydrogen in martensite is orders of magnitude lower than in austenite and its diffusivity is much higher than austenite .…”

Dilatometric Study of Continuous Annealing of a Cold‐Rolled Austenitic Stainless Steel

“…[1][2][3] Owing to a good combination of excellent ductility, toughness, and corrosion resistance, commercial austenitic stainless steels (ASSs) have been widely used as structural materials for various engineering applications. [4][5][6][7][8][9] However, they exhibit quite low yield strength derived from the coarse γ-austenite (face-centered cubic [FCC]) phase. [9][10][11][12] According to several studies conducted in this research area, the yield strengthening of ASSs can be reached through severe plastic deformation (SPD) methods [6,[11][12][13] via the activation of various strengthening mechanisms, such as grain refining, transformation strengthening, and work hardening.…”

“…[12,13] Furthermore, it has also been reported that ultrafine grained (UFG) ASSs can be fabricated by conventional rolling and annealing processes. [4][5][6][7]9,[11][12][13][14][15][16][17] The principle is to use cold rolling (CR) to produce DIM and the subsequent annealing to revert the DIM back to nano-or ultrafinegrained austenite under specific conditions. [4][5][6]9,[12][13][14][15]17] Additionally, the ultrafine or fine-grained strengthening is a hopeful pathway to improve simultaneously the yield strength, toughness, and corrosion resistance of ASSs without obviously deteriorating ductility and work-hardening ability.…”

“…[4][5][6][7]9,[11][12][13][14][15][16][17] The principle is to use cold rolling (CR) to produce DIM and the subsequent annealing to revert the DIM back to nano-or ultrafinegrained austenite under specific conditions. [4][5][6]9,[12][13][14][15]17] Additionally, the ultrafine or fine-grained strengthening is a hopeful pathway to improve simultaneously the yield strength, toughness, and corrosion resistance of ASSs without obviously deteriorating ductility and work-hardening ability. [12] It has been demonstrated that during the early stages of lowtemperature deformation of ASSs, ε (hexagonal close packed [HCP], nonferromagnetic) martensite forms at shear bands and stacking faults (SF) whereas α 0 (body-centered cubic [BCC], ferromagnetic) martensite nucleates at the intersections of the shear bands.…”