Continuous Cooling Transformation Diagram and Properties of Hot Forming Steel

2012 ◽  
Vol 152-154 ◽  
pp. 585-588 ◽  
Author(s):  
Mei Zhang ◽  
Qing Shan Li ◽  
Kun Han ◽  
Chao Bin Huang ◽  
Ru Yi Wu ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Heating Temperature ◽  
Tensile Tests ◽  
Processing Parameters ◽  
Total Elongation ◽  
Hot Forming ◽  
Forming Process ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Metallographic Observation

Continuous cooling transformation (CCT) diagram of steel 22MnB5 was studied using dilatometer method. The influence of the hot forming process parameters, such as the heating temperature and holding time on the mechanical properties and microstructure of stamped parts was analyzed by tensile tests and the metallographic observation on the parts with various processing parameters. The microstructural evolution obtained from the dilatometer samples reveals that the cooling rates not smaller than 20K/s induced fully martensitic microstructure. As the cooling rate decreasing, more ferrite and pearlite or more bainitic microstructure forms. Tensile tests results show an excellent tensile strength and ductility combination of 22MnB5. The tensile strength and yield strength reach 1500MPa and 1200MPa respectively, with total elongation of around 10%.

Structure and properties of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/poly(L-lactic acid) quasi core/sheath melt-electrospun microfibers

2018 ◽  
Vol 89 (9) ◽  
pp. 1770-1781 ◽  
Author(s):  
Huaizhong Xu ◽  
Benedict Bauer ◽  
Masaki Yamamoto ◽  
Hideki Yamane
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Lactic Acid ◽  
Tensile Tests ◽  
Processing Parameters ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Diffraction Patterns

A facile route was proposed to fabricate core–sheath microfibers, and the relationships among processing parameters, crystalline structures and the mechanical properties were investigated. The compression molded poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH)/poly(L-lactic acid) (PLLA) strip enhanced the spinnability of PHBH and the mechanical properties of PLLA as well. The core–sheath ratio of the fibers was determined by the prefab strip, while the PLLA sheath component did not completely cover the PHBH core component due to the weak interfacial tension between the melts of PHBH and PLLA. A rotational target was applied to collect aligned fibers, which were further drawn in a water bath. The tensile strength and the modulus of as-spun and drawn fibers increased with increasing the take-up velocities. When the take-up velocity was above 500 m/min, the jet became unstable and started to break up at the tip of the Taylor cone, decreasing the mechanical properties of the fibers. The drawing process facilitated the crystallization of PLLA and PHBH, and the tensile strength and the modulus increased linearly with the increasing the draw ratio. The crystal information displayed from wide-angle X-ray diffraction patterns and differential scanning calorimetry heating curves supported the results of the tensile tests.

NUMERICAL MODELING OF PHASE TRANSFORMATION DURING GRINDING PROCESS

2017 ◽  
Vol 79 (5) ◽  
Author(s):  
Syed Mushtaq Ahmed Shah ◽  
M. A. Khattak ◽  
Muhammad Asad ◽  
Javed Iqbal ◽  
Saeed Badshah ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Phase Transformations ◽  
Thermal Stresses ◽  
Heating Temperature ◽  
Temperature History ◽  
Grinding Process ◽  
Cooling Rates ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Heating And Cooling

The rapid heating and cooling in a grinding process may cause phase transformations. This will introduce thermal strains and plastic strains simultaneously in a workpiece with substantial residual stresses. The properties of the workpiece material will change when phase transformation occurs. The extent of such change depends on the temperature history experienced and the instantaneous thermal stresses developed. To carry out a reliable residual stress analysis, a comprehensive modelling technique and a sophisticated computational procedure that can accommodate the property change with the metallurgical change of material need to be developed. The objective of this work is to propose a simplified model to predict phase evolution during given temperature history for heating and cooling as encountered during grinding process. The numerical implementation of the proposed model is carried out through the developed FORTRAN subroutine called PHASE using the FEM commercial software Abaqus®/standard. Micro-structural constituents are defined as state variables. They are computed and updated inside the subroutine PHASE. The heating temperature is assumed to be uniform while the cooling characteristics in relation to phase transformations are obtained from the continuous cooling transformation (CCT) diagram of the given material (here AISI 52100 steel). Four metallurgical phases are assumed for the simulations: austenite, pearlite, bainite, and martensite. It was shown that at low cooling rates high percentage of pearlite phase is obtained when the material is heated and cooled to ambient temperature. Bainite is formed usually at medium cooling rates. Similarly at high cooling rates maximum content of martensite may be observed. It is also shown that the continuous cooling transformation kinetics may be described by plotting the transformation temperature, directly against the cooling rate as an alternative to the continuous cooling transformation diagram. The simulated results are also compared with experimental results of Wever [20] and Hunkle [21] and are found to be in a very good agreement. The model may be used for further thermo-mechanical analysis coupled with phase transformation during grinding process.

Fracture Behaviors of the Rolled Isotactic Polypropylene

2014 ◽  
Vol 529 ◽  
pp. 237-241
Author(s):  
Juan Jia ◽  
Shuang Xin Liu ◽  
Dierk Rabbe
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Isotactic Polypropylene ◽  
Rolling Direction ◽  
Tensile Tests ◽  
Total Elongation ◽  
Tensile Fracture ◽  
Tensile Sample ◽  
Fracture Surfaces ◽  
Fracture Behaviors

The mechanical properties of the rolled isotactic polypropylene and the morphology of fracture surfaces were measured and observed by tensile tests and the scanning electron microscopy. And then the tensile fracture behaviors along the rolling and transvers directions of the rolled samples were analyzed. After rolling, strong anisotropy mechanical properties occurred along the rolling and transverse directions: high tensile strength with low total elongation along the rolling direction and low tensile strength with high total elongation along the transverse direction. After tensile test, three characteristic structures were found on the fracture surfaces. The tensile fracture behavior of the rolled samples is: stress concentration happens on the edge of tensile sample and then fracture develops to the center part of the tensile sample. When the fracture is big enough, the tensile sample will be failed very quickly.

Study on High Temperature Creep Test of P92 Material Based on the Minimally Invasive Technique

2017 ◽  
Vol 734 ◽  
pp. 159-167
Author(s):  
Chao Zhou ◽  
Jun Liang ◽  
Bin Wang
Keyword(s):  
Tensile Strength ◽  
High Temperature ◽  
Yield Strength ◽  
Creep Test ◽  
Uniform Elongation ◽  
Tensile Tests ◽  
Total Elongation ◽  
Invasive Technique ◽  
P92 Steel ◽  
Power Law Creep

The tensile and creep properties of P92 steel have been studied using a precision tensile and creep test machines for miniature and conventional specimens under various stress level at 625°C. The results showed that the data stability of miniature plate specimens is high whether at room or high temperature tensile tests. Compared with the conventional plate specimens, tensile strength, yield strength and total elongation is slightly lower, the uniform elongation is higher for miniature plate specimens at room temperature. By contrast, the tensile strength and uniform elongation is slightly higher, and the yield strength and total elongation is lower at high temperature. Besides, there had similar creep curves between miniature and conventional specimens, and the creep rupture time and minimum creep rate are closer under the same stress. By comparing the power law creep index and damage tolerance factor at the second creep stage, it can be derived that the creep mechanism is identical for the micro and conventional specimens, which is controlled by the dislocation movement.

scholarly journals Recrystallization and Mechanical Behavior of High Mn and Low C Cold Rolled and Annealed Steel with TWIP Effect

2012 ◽  
Vol 715-716 ◽  
pp. 579-584 ◽  
Author(s):  
Dagoberto Brandao Santos ◽  
Berenice Mendonça Gonzalez ◽  
Elena V. Pereloma
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Driving Force ◽  
Vickers Microhardness ◽  
Tensile Tests ◽  
Total Elongation ◽  
Strain Hardening Exponent ◽  
Twip Steels ◽  
Cold Rolled ◽  
Annealed Steel

ncreasing demand for automotive vehicles with reduced weight, improved crashworthiness and passengers safety has steamed the research of new Twinning Induced Plasticity (TWIP) steels. In this work the effect of annealing between 400 and 900°C on the microstructure and mechanical properties of hot and cold rolled 0.06C-24Mn-3Al-2Si-1Ni (wt%) steel with TWIP effect was investigated. The results have shown that steel exhibits fast recrystallization kinetics with a low amount of recovery, which results in a high driving force for the former. Mechanical properties were determined using Vickers microhardness and tensile tests. Tensile strength of 670 MPa with 54% of total elongation, and strain hardening exponent of 0.57 were reached after annealing at 900°C.

scholarly journals On the variability in static and cyclic mechanical properties of extruded 7075-T6 aluminum alloy

2021 ◽  
Author(s):  
Matteo Benedetti ◽  
Cinzia Menapace ◽  
Vigilio Fontanari ◽  
Ciro Santus
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Tensile Tests ◽  
Total Elongation ◽  
Extrusion Ratio ◽  
Cycle Fatigue ◽  
Hardness Tests ◽  
Fatigue Endurance

The present paper investigates the variability in the static and cyclic properties of two nominally identical supplies of the aeronautical Al grade 7075-T6. Samples were extracted from extruded bars of 15 mm and 60 mm diameter and with slightly different chemical composition. Noticeable differences were found in tensile strength, total elongation, low- and high-cycle fatigue strength, despite the nearly identical hardness value. The diverse mechanical behavior has been imputed to different extrusion ratio and therefore work hardening along with a more or less fine distribution of precipitates and dispersoids. The high-cycle fatigue strength was found to be in direct correlation with the monotonic yield strength and the size of the largest intermetallic precipitate. A simple equation based on Murakami sqrt(area) parameter is proposed to predict the fatigue endurance. Tensile tests and microstructural analyses are recommended instead of conventional hardness tests to have a tighter quality control on the mechanical properties of semifinished products.

Step-Sintering of Fe-(1-3)%Mn-0.8%C Steels

2020 ◽  
Vol 405 ◽  
pp. 373-378
Author(s):  
Monika Tenerowicz-Żaba ◽  
Maciej Sułowski
Keyword(s):  
Tensile Strength ◽  
Phase Transformation ◽  
Cooling Rate ◽  
Heating Rate ◽  
Microstructure Evolution ◽  
Room Temperature ◽  
Sintering Temperature ◽  
Tensile Tests ◽  
Transformation Temperatures ◽  
Metallographic Observation

The aim of the study was to examine how the microstructure changes during heating of Fe-Mn-C system (step-sintering). Mixtures of powders containing 1 – 3 % Mn and 0.8 % C were prepared in Turbula TC2 mixer for 30 minutes. Before step-sintering, the dilatometric investigations were carried out, which allowed to obtain phase transformation temperatures of Fe-(1-3)Mn%-0.8%C system. Following dilatometric investigations, 4 steps – temperatures were determined dependently of isothermal sintering temperature. The commonly used industry temperatures – 1120 °C and 1250 °C – were set as target temperatures. For each of them, 4 heat steps were carried out. The procedure of investigations was as follows: samples were heated to the step temperature with heating rate 60 K/min, then isothermally sintered at step temperature for 5 min, and finally cooled to the room temperature with cooling rate ~ 66 K/min. Fe-Mn-C samples were mechanically (tensile) tested. After tensile tests, metallographic observations of the samples were performed. Based on the results obtained, the tensile strength was increasing with the increasing of the step temperature. The metallographic observation showed the microstructure evolution – with increasing the step temperature, decreasing of porosity was observed.

Numerical Simulation and Experiment of Aluminum Sheet Metal Springback in New Quenching State

2010 ◽  
Vol 97-101 ◽  
pp. 2567-2570
Author(s):  
Lei Chen
Keyword(s):  
Numerical Simulation ◽  
Tensile Strength ◽  
Numerical Method ◽  
Sheet Metal ◽  
Total Elongation ◽  
Forming Process ◽  
Tool Shape ◽  
Metal Rubber ◽  
Rubber Forming ◽  
Simulation And Experiment

2024-T3 aluminium sheet metal rubber forming process after quenching is studied. The tensile properties of 2024-T3 after quenching are measured. It is found that the yield strength and ultimate tensile strength are reduced, whilst total elongation value is increased. Springback character of rubber forming is studied by numerical method and springback compensation of rib flanging is studied. The simulation is compared with experiment. It is found that the tool shape considering springback is got using numerical method. The parts after springback achieve the design accuracy. So the method can be used in the application of rubber net forming.

scholarly journals The Impact of Retained Austenite on the Mechanical Properties of Bainitic and Dual Phase Steels

2022 ◽  
Author(s):  
Bogusława Adamczyk-Cieślak ◽  
Milena Koralnik ◽  
Roman Kuziak ◽  
Kamil Majchrowicz ◽  
Tomasz Zygmunt ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Transformation Temperature ◽  
Retained Austenite ◽  
Tensile Tests ◽  
Total Elongation ◽  
Isothermal Transformation ◽  
Bainitic Transformation ◽  
Bainitic Steel ◽  
Continuous Cooling

AbstractThis paper presents the microstructural changes and mechanical properties of carbide-free bainitic steel subjected to various heat treatment processes and compares these results with similarly treated ferritic–pearlitic steel. A key feature of the investigated steel, which is common among others described in the literature, is that the Si content in the developed steel was >1 wt.% to avoid carbide precipitation in the retained austenite during the bainitic transformation. The phase identification before and after various heat treatment conditions was carried out based on microstructural observations and x-ray diffraction. Hardness measurements and tensile tests were conducted to determine the mechanical properties of the investigated materials. In addition, following the tensile tests, the fracture surfaces of both types of steels were analyzed. Changing the bainitic transformation temperature generated distinct volume fractions of retained austenite and different values of mechanical strength properties. The mechanical properties of the examined steels were strongly influenced by the volume fractions and morphological features of the microstructural constituents. It is worth noting that the bainitic steel was characterized by a high ultimate tensile strength (1250 MPa) combined with a total elongation of 18% after austenitizing and continuous cooling. The chemical composition of the bainitic steel was designed to obtain the optimal microstructure and mechanical properties after hot deformation followed by natural cooling in still air. Extensive tests using isothermal transformation to bainite were conducted to understand the relationships between transformation temperature and the resulting microstructures, mechanical properties, and fracture characteristics. The isothermal transformation tests indicated that the optimal relationship between the sample strength and total elongation was obtained after bainitic treatment at 400 °C. However, it should be noted that the mechanical properties and total elongation of the bainitic steel after continuous cooling differed little from the condition after isothermal transformation at 400 °C.

scholarly journals Application of Direct Resistance Heating in Hot Forging and Analysis of Processing Parameters based on Thermo-electro-mechanical Coupling FEM

2018 ◽  
Vol 37 (6) ◽  
pp. 531-538
Author(s):  
Men Zhengxing ◽  
Wang Menghan ◽  
Ma Yaxin ◽  
Yue Taiwen ◽  
Liu Ruilin
Keyword(s):  
Contact Resistance ◽  
Heating Temperature ◽  
Hot Forging ◽  
Processing Parameters ◽  
Experimental Results ◽  
Transient Temperature ◽  
Resistance Heating ◽  
Forming Process ◽  
Mechanical Coupling ◽  
Forming Temperature

AbstractA series of experiments were designed in order to directly heat the billet of 42CrMo4 to the forming temperature in the dies prior to forming and continue to heat the billet during the forming process. Processing parameters during heating and forming were investigated by experimental method and thermo-electro-mechanical coupling FEM. The experimental results show that prior to forming the billet could be rapidly heated to forming temperature under relatively low initial contact pressure, and the heating temperature was proportional to the square of the current intensity. When the heating current remained constant, the heating temperature could not increase with heating time. During the forming process, the billet cooling rate slowed down and the forming time was extended due to the continuous resistance heating during forming. Finally, an incrementally coupled thermo-electro-mechanical model has been developed to analyze the hot-forging process by direct resistance heating. To obtain the transient temperature field prior to forming, a simple model of contact resistance was used in the thermal-electrical simulation, in which the electrical conductance of the contact resistance was proportional to the heating temperature. Contrasted the experimental results and the simulation results, it was found that they coincided well.

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