Microstructure Evolution in TRIP-aided Seamless Steel Tube during T-Shape Hydroforming Process

• Correspondence Author:Zicheng Zhang
• Journal:Materials Characterization
• Volume:94
• Impact Factor:4.7
• DOI number:10.1016/j.matchar.2014.05.020
• Abstract:Transformation-induced plasticity aided seamless steel tube comprising of ferrite, bainite, and metastable austenite was processed through forging, piercing, cold-drawing, and two-stage heat treatment T-shape hydroforming is a classic forming method for experimental research and practical production. The current work studied austenite-to-martensite transformation and microcrack initiation and propagation of the tube during T-shape hydroforming using electron backscattering diffraction, scanning electron microscopy, and transmission electron microscopy. The strain distribution in the bcc-phase and fcc-phase was studied by evaluating changes in the average local misorientation. Compared to the compressive stress, metastable austenite with similar strain surrounding or inside the grains transformed easier under tensile loading conditions. The inclusions were responsible for microcrack initiation. The propagation of the cracks is hindered by martensite/austenite constituent due to transformation induced plasticity effect. The volume fraction of untransformed retained austenite decreased with increase in strain implying transformation-induced plasticity effect. (C) 2014 Elsevier Inc. All rights reserved.
• Key Words:TRIP steel;Seamless steel tube;Hydroforming;Microstructure evolution;Retained austenite
• Indexed by:SCI JCR Q3
• Page Number:149-160
• Translation or Not:no