13th International Conference on the Technology of Plasticity (ICTP 2021): Microstructure & Damage Development I
Program Organizers: Glenn Daehn, Ohio State University; Libby Culley, The Ohio State University; Anupam Vivek, Ohio State University; Jian Cao, Northwestern University; Brad Kinsey, University of New Hampshire; Erman Tekkaya, TU Dortmund; Yoshinori Yoshida, Gifu University
Monday 10:20 AM
July 26, 2021
Room: Virtual: Room C
Location: Virtual
Session Chair: Till Clausmeyer, Technische University Dortmund
Hardening/Softening Characteristics of a TRIP-assisted Duplex Stainless Steel under Cyclic Deformation: Miao Jin1; Lei Chen1; Zongyuan Zou1; Shuo Hao1; Hongzhong Wang1; Qun Li1; Shiyan Zhao1; 1Yanshan University
Recently, a series of economical duplex stainless steel (DSS) with transformation induced plasticity(TRIP) effect which improves the mechanical properties have been developed by replacing Ni-Mo with Mn-N. The mechanical properties of the above TRIP-assisted DSS under cyclic loading condition were studied and the microstructural mechanism was characterized by TEM. The results show that it's cyclic hardening/softening characteristics are sensitive to strain amplitude and the number of cycles(N). With a relatively small strain amplitude, cyclic hardening occurs firstly (N < 5), then cyclic softening starts and trends to stabilization gradually. With a relatively large strain amplitude, after a rapidly cyclic hardening (N<5), it is softening continuously until failure. The dislocation walls formed in ferrite during cyclic deformation which are responsible for the overall cyclic softening; While austenite undergoes cyclic induced ε martensite transformation at relatively large strain amplitude whereby the cyclic softening is suppressed.
Relaxation Characteristics of Creasing Process of Scored Paperboard for Liquid Container: Shigeru Nagasawa1; Takaomi Nagumo1; Azusa Sakamoto1; Kazuki Umemoto1; 1Nagaoka University of Technology
A knowledge of dynamic bending moment resistance acting on a hinge, which is folded on a creased line, is important in order to adjust mechanical conditions for boxing a paperboard. In this work, dynamic creasing characteristics of liquid-container-purpose paperboard of basis weight 313 g/m2 were investigated, when the holding time of a position of creasing knife was varied with the specified indentation depth. In the scoring process, the time-dependent behaviors of reaction force and the permanent scored depth were experimentally investigated for the elapsed time of 100 seconds. When using the paperboard scored with the specified indentation depth and varying the holding time, the bending moment response at a 90 degree folding test was investigated. In this folding and unfolding process, the effect of holding time at the scoring process on the bending moment resistance was analyzed, especially for characterizing the initial gradient of stiffness.
Temperature Dependent Fracture Loci Of AZ31 Magnesium Alloy Sheets: Rachele Bertolini1; Qiaoling Wang1; Andrea Ghiotti1; Stefania Bruschi1; 1University of Padua
Magnesium alloys have been used in the automotive and aereospace industry for several years, thanks to their high strength-to-density ratio. Their mechanical characteristics at room and even at elevated temperature have been well-studied, whereas, when it comes to temperatures lower than the room one, only a few studies are available in literature. To this aim, the present paper investigates the mechanical behaviour of AZ31 magnesium alloy sheets deformed at different temperature regimes. Tensile tests till fracture were carried out at room temperature, -100 °C, -50°C, 100°C and 300°C using different specimen geometries in order to vary the stress triaxiality. The fracture strain values were identified making use of a combined numerical-experimental approach, whereas the fracture surfaces were qualitatively characterized by means of stereoscopy and scanning electron microscopy. Finally, the AZ31 fracture locus as a function of the stress state and temperature was constructed.
Application of the Nondestructive Evaluation (NDE) Method to Evaluate the Sheared Edge Quality and Edge Cracking: Clare Gu1; Nikky Pathak1; Shaun Freed1; Hyunok Kim1; 1EWI
Evaluating the shear edge quality and edge cracking is important in forming the advanced high-strength steel for automotive structural parts. This paper introduces the eddy-current based NDE method to evaluate the sheared edge quality. Using different shear clearances from 5 to 25% of the sheet thickness, different work hardening magnitudes were applied on the sheared edges which varied the local formability. The NDE sensor scanned the sheared DP780 blanks to obtain the NDE data. To compare the NDE data to the work hardening level of the sheared edge, the microhardness was measured. The edge formability was evaluated using half specimen dome test (HSDT) with digital image correlation (DIC) to correlate the failure strain with the NDE data. The NDE result shows good correlation with edge formability and microhardness. With additional development effort, the eddy-current based NDE method can be implemented as a real-time monitoring tool for rapid edge quality evaluation.
Study of Hydrogen Embrittlement Behavior of Hot-stamped Ultra-high Strength Steel: Huizhen Zhang1; Xiaoxin Zhang1; Johnston Tang1; Xianhong Han1; 1Shanghai Jiao Tong University
The hydrogen embrittlement (HE) behavior of hot-stamped ultra-high strength boron steel B1500HS was studied. A series of tensile tests and microstructure observations for B1500HS samples after electrochemical hydrogen charging were performed and analyzed. Based on the experimental results, some interesting phenomena were studied. Firstly, the relationship between the mechanical properties of hot stamped B1500HS and the hydrogen concentration and charging time were presented; Secondly, both reversible HE and irreversible HE were revealed and the conditions leading to them were discussed; Thirdly, the effects of tensile rate on B1500HS after hydrogen charging were also studied. Besides, the mechanism of the above phenomena were further involved in this work.