Triaxiality Factor Research Articles

Sensitivity of Stainless Steel Fracture to Triaxiality Factor and Lode Parameter Using Dislocation Density Approach

This work is devoted to the analysis of the influence of the triaxiality factor and the Lode parameter on the ductile fracture of a stainless steel tube. A micromechanical-based model incorporating several deformation mechanisms and formulated in the framework of the dislocation density theory is chosen to model the viscoplastic behavior of the 316L stainless steel. After adaptation of the implementation of the model into the finite element code Abaqus 2020 and the calibration of the model parameters with experimental available results, simulations of healthy and notched tubular specimens were carried out. In order to vary the triaxiality and Lode angle, we used specimens of different sizes and notch shapes. The results showed the capacity of the model to reproduce the experimental results of tubular structures. It was found that the strength and ductility of the specimens depend on the Triaxiality Factor and Lode Parameter.

Effect of notch angle on creep deformation and rupture behavior of 304HCu SS

Abstract Multiaxial creep deformation behaviour of U-notched 304HCu austenitic stainless steel (304HCu SS) has been studied by altering the angle of the U-notch, by 30°, 60°, 90°, and 120°, for a fixed root radius of 1.25 mm. The associated stress concentration factor for the U-notch geometry is about 1.8–1.86 with decrease in notch angle. Creep rupture lives of all notched specimens are above the un-notched specimen. However, decrease in rupture life and increase in creep rupture ductility has been observed with an increase in notch angle. At all notch angles, nearly intergranular creep cavitation failure with isolated cavities was observed at the notch center. In contrast, at the notch root, with decrease in notch angle the fracture mode changed from mixed mode to intergranular fracture. Finite element analysis (FEA) of stationary state of stress distribution indicated that von-Mises stress throughout the notch throat plane and maximum principal stress near the notch root region were found to increase with increase in notch angle. However, away from the notch root the maximum principal stress was found to decrease with increase in notch angle. Hydrostatic stress distribution remained same near the notch root at all the notch angles, but tends to increase towards the specimen center with decrease in notch angle. Similarly, at the notch throat plane, triaxiality factor (TF) was found to increase with decrease in notch angle. The creep damage evaluated through FEA coupled with continuum damage mechanics (CDM) proposed by Kachanov-Rabotov (K-R) model was found to increase with an increase in notch angle, resulting in decrease in creep rupture life. Creep damage evaluated as a function of notch depth, during initial creep exposure, revealed significant damage for 1.675 mm notch depth in comparison to 2 and 2.5 mm notch depths which resulted in lower rupture life for 1.675 mm notch depth.

Study on Mechanical Calculation Method of Injection-production String in Changqing Gas Storage

on the basis of previous studies, According to the working conditions of injection and production wells in gas storage,this paper selects the mathematical model of the downhole string suitable for Changqing gas storage under the effects of piston, axial force, expansion, temperature and spiral bending. The mechanical analysis and calculation of injection-production string under simulated working condition and actual working condition are carried out by using corresponding mechanical analysis software, and the parameters such as the axial load, triaxial Factor of safety, minimum absolute triaxial Factor of safety, string elongation, string shortening are given, according to the calculation results, the safety strength of injection-production string is checked, and the load safety criterion for production and operation of string is given.Field Test and calculation of injection-production string are carried out. According to the actual test results, the deformation rule of the injection production string under the actual gas injection condition is summarized, and compared with the results calculated by the software, which verifies the accuracy of the calculating software and forms the method of the strength check of the injection and production string. It can provide effective evaluation means for the safe operation of injection and production string in gas storage. The safety failure of the injection and production pipe string is reduced, the safety and efficient operation of the gas storage is ensured.

New insights into the anisotropic ductility of additively manufactured Inconel 718

Anisotropic ductility in additively manufactured (AM) alloys, namely better ductility along the building direction (BD) has been extensively studied and traditionally attributed to the crystallographic texture. However, recent studies have shown significant ductility anisotropy in weakly or non-textured AM alloys, indicating that other factors may also play critical roles. To explore this, AM Inconel 718 with weak crystallographic texture was selected as the model material, and the in-situ high-energy X-ray diffraction tests together with multiscale microstructural characterization techniques were performed to explore the deformation micromechanisms. The results of this study, for the first time, revealed that the better ductility in the vertical specimen (loading parallel to BD) was partially due to the negative stress triaxiality factor (TF) of the {220} grains during plastic deformation, which results in the shrinkage or even healing of the microvoids. Furthermore, the δ-phase alignment in conjunction with grain boundary orientation were also proved to have a pronounced impact on the anisotropic ductility of AM alloys. On the other hand, though in the overall weak-textured microstructure, the proportion of 〈101〉 grains were marginally over other grains. Thus, the positive effect of {220} grains on ductility was stronger than the negative effect of {200} and {311} grains, contributing to the excellent failure elongation exceeding 12% for both samples. The findings of this study shed new light on the mechanisms underlying the anisotropic ductility of AM alloys and provide insight into strategies for enhancing their performance.

Analysis of Phenomenon of Plasticity Loss of Steel Core Made by Selective Laser Melting Method in Zone of Pressure Mould Conformal Cooling Channel.

This paper presents the results of testing the mechanical properties of maraging steel 1.2709 that were obtained by the SLM method under uniaxial and triaxial states of stress. The triaxial state of stress was realised by making circumferential notches in the samples with different radii of rounding. The specimens were subjected to two types of heat treatment, which consisted of ageing at 490 °C and 540 °C for 8 h. The results of the tests that were conducted on the samples were considered as references and compared with the results of the strength tests that were conducted directly on the SLM-made core model. Differences were found between the results of these tests. Based on the experimental results, the relationship between the equivalent strain of the specimen in the bottom of notch εeq and triaxiality factor η was determined. Function εeq = f(η) was proposed as a criterion for the decrease in the plasticity of the material in the area of the pressure mould cooling channel. Using the FEM method, equivalent strain field εeq and triaxiality factor η were determined in the conformal channel cooled core model. Based on the proposed criterion of plasticity loss and the results of numerical calculations, it was shown that the values of equivalent strain εeq and triaxiality factor η in the core that was aged at 490 °C did not meet this criterion. On the other hand, the values of strain εeq and triaxiality factor η did not exceed the safety limit when ageing was carried out at 540 °C. The plasticity loss method presented in this paper assumes that the value of the triaxiality factor in the vicinity of the channel is influenced by the shape, cross-sectional dimensions and trajectory of the channel axis. Using the methodology proposed in this paper, it is possible to determine the value of allowable deformations in the cooling channel zone and to determine whether the heat treatment applied to the SLM steel does not cause an excessive reduction in the plastic properties.

A physically-based representative stress methodology for predicting stress rupture life of Ni-based DS superalloy

Smooth and three types of U-shape single-edge notched plate specimens adopted to experimentally investigate stress rupture behavior of Ni-based Directionally Solidified (DS) superalloy at 850 °C exhibit notch weakening effect and multi-source cracking initiation near the notch root. However, stress rupture behavior of smooth and V-shape notched round bars at 1040 °C revealed by Li et al indicates notch strengthening effect and creep micro-holes originating mostly from the central portion. A combined creep-viscoplastic constitutive model is employed to analyze the distribution of stress, strain and stress Triaxial Factor (TF) near the notch root. The different stress distribution and creep restraint between asymmetric notched plate specimens and symmetric notched round bars are the main reasons for the corresponding failure mechanism. Meanwhile, a good qualitative relationship exists between TF value and stress rupture life of notched specimen. Especially, the area with maximum TF value (TFmax) is highly consistent with creep damage initiation region. Hence, based on the distribution characteristics of the initial tensile loading, a representative stress method independent of time -changing creep load at the location of TFmax is conducted for life prediction. The predicted results of both smooth and notched plate specimens and round bars agrees well with the experimental results.

Numerical study on the hot compression test for bulk metal forming application

In this study, a comparison between the well-established Lagrangian approach and the Arbitrary Lagrangian–Eulerian (ALE) approach is presented. This comparison aims to verify the ALE's approach suitability for modeling thermomechanical processes. After that, a study on the material's stress state evolution inside the specimen is provided. The stress state is evaluated through the triaxiality factor and Lode parameter. Ideally, under pure compression, these parameters' values are − 1/3 and − 1, respectively. However, it is not possible to achieve ideal conditions in actual experiments. The Lagrangian model was done in QForm, and the ALE model was done in LS-Dyna. The results from both models are in good agreement between them and agree with the force vs. stroke measured during the experiments. Two paths were defined to study the stress state inside the sample, in the radial direction (equator line) and axial direction (axial line). It was concluded that some areas in both paths might be considered as approximately under pure compression stress state. In addition, the ALE approach accuracy for thermomechanical modeling was verified.

Interaction of crack-tip constraint and welding residual stresses on the fracture behavior of Ni-based alloy

The present paper aims to study the effect of crack-tip geometrical constraints and welding residual stresses (WRS), as well as their interaction on fracture behavior of IN939 superalloy, which is widely used in gas turbine hot section components, such as turbine vanes. For the thermal–mechanical simulation of welding processes, a finite element (FE) model was developed, and the predicted WRS was verified through experiments. Two welding paths and two mechanical boundary conditions were considered to develop four different WRS distributions within the same geometry. These results were mapped to the validated fracture finite element models. By varying the loading conditions, two sets of specimens with high and low geometrical constraints were achieved in the same geometry. Two-parameter fracture mechanics analyses were then used to examine the effects of four WRS profiles and geometrical constraints on the fracture behavior of each set. Generally, the impact of WRS is more evident in specimens with lower geometrical constraints. The fracture behavior might be unexpectedly affected if the WRS changes from tensile to compressive near the crack tip. Using the maximum stress triaxiality factor, it was shown that the fracture behavior as a function of WRS is better demonstrated than that of the Q-constraint parameter.

Development of a non-local approach for life prediction of notched specimen considering stress/strain gradient and elastic-plastic fatigue damage

In this study, a non-local approach is developed for the fatigue life prediction of notched specimens, considering stress/strain gradient and elastic-plastic fatigue damage. The damage coupled constitutive models are presented to model the mechanical behavior of material. The critical plane method and triaxiality factor are employed to determine the location of the couple point. The gradient values of mechanical quantities are then computed, and the modified coefficients in damage models are acquired. The numerical simulations are implemented to compute the damage evolution process and predict fatigue life. Meanwhile, the coupling effects between stress field and damage field are considered. The predicted results are verified by experimental data, and also compared with the local method. Finally, the influence of stress concentration factor, shape of notch, and cyclic variation of stress/strain gradient are further investigated.

Ductile fracture of DX51D material sheet metal panel produced by hemming process

In this study, the fracture problem occurring in the bending areas of the sheet metal panel produced by the hemming process was investigated by numerical method. The part is produced with cold-rolled continuous galvanized DX51D grade material which is commonly used. As is known, there is no upper yield stress limit value for this material according to EN 10346:2015. In addition to this, for this steel grade when the yield and tensile stresses increase, ductility capability decreases significantly. Also, when the metal forming simulations are done with only uniaxial tensile test data of material, unexpected failures could arise for the hemming process. Therefore, the type of stress that occurred on the material by the process applied in the production should be carefully examined and material data should be extracted for dominant stress types. The use of this material without limiting mechanical properties can cause unexpected cracks and tears, especially in processes with high plastic deformation such as hemming. In order to observe the fracture occurrence, the stress triaxiality factor of the material was examined and the dominant stress triaxiality value with strain to fracture path in the hemming process was determined with finite element analysis. Due to their similar mechanical properties, being used as raw material for DX51D and having ductile fracture parameters available in the literature, hot-rolled S235JR and S275JR materials are chosen to observe fracture event in numerical analysis. Equivalent strain to fracture-stress triaxiality and lode angle curves were used with the Hosford-Coulomb ductile fracture model to examine the effects on the hemming process. All numerical calculations were performed in the commercial Altair RADIOSS software that can perform high nonlinearity calculations. Finally, a performance comparison was made between materials and the experiment for the hemming process.

Constitutive Model and Fracture Criterion of Q345 Steel Welded Joints

Welding joint is a key component in steel structure engineering, which is often subjected to complex stress and becomes the weak link of building structure, and different fracture modes may appear under different stress. In this study, the ductile fracture of Q345 steel welded joint was investigated by selecting the base material and heat‐affected zone (HAZ) material. Based on the J–C (Johnson–Cook) fracture model of stress triaxiality factor, a series of round bar specimens were designed for the tensile test, and the variation of minimum diameter and gauge distance was tracked in real time by digital image correlation (DIC) technology, and the cloud map of strain distribution in the whole loading process was obtained. The constitutive model and fracture criterion model of Q345 steel welded joint base material and HAZ material are established through experimental measurement. The results show that the maximum triaxial stress is at the center root of the minimum diameter of the notched round bar tensile specimen, the sudden change of the notched edge will lead to stress concentration, the stress change of the notch section is the most significant, extending from near the notch, the maximum strain is at the root of the notch, and the fracture position appears at the minimum section of the notch. According to the true stress‐strain curve of a standard tensile specimen and the least square method, the values of parameters A, B, and N of the J–C (Johnson–Cook) constitutive model of base material and HAZ material are 379.80, 452.89, and 0.37 and 392.90, 540.61, and 0.49, respectively. The fracture strains of the base metal and HAZ material under different triaxial stresses were measured experimentally, and the J–C fracture model was fitted. The values of failure criterion parameters D1, D2, and D 3 were 1.025, −0.008, and 3.617 and 0.678, −2.689E‐5, and 7.683, respectively. This provides experimental parameters for mechanical properties and fracture models of welded joints in structural engineering, refined finite element models considering material failure for structural numerical analysis, and basic data for evaluation and design of building structures, which have good social and economic benefits.

Application of machine learning in rapid analysis of solder joint geometry and type on thermomechanical useful lifetime of electronic components

Rapid reliability analysis of the solder joints in the electronic devices identifies as an appeared gap in the design stage. This paper demonstrates the feasibility of employing the neural network in the solder joint useful lifetime estimation. A dataset is prepared for training a deep neural network under different conditions using finite element simulations. The contributory parameters including thermal specifications, solder joint geometry and solder joint type are considered in 420 finite element simulations. While the proposed approach has a remarkably quick reliability assessment, the predicted results showed a maximum root mean square error of 3.2%. The results reveal that there exists an optimum solder joint volume in which the maximum useful lifetime under the certain thermal loading. Also, it is found that the hourglass type solder interconnection has better performance in comparison with barrel type solder interconnection as the reliability perspective owing to the more gentle triaxiality factor. Ability of rapid reliability analysis and effects consideration of key parameters on the solder joint reliability make this proposed method attractive in the design stage of electronic devices.

Investigation on in-plane and out-of-plane constraint effects for plates with I-II mixed mode cracks under biaxial compressive loading

Crack sizes, geometrical configurations of specimens and structures, as well as loading conditions have significant effect on in-plane and out-of-plane constraint effects. Safety assessment with constraint effects can effectively improve the accuracy. There are prominent discrepancies between compressive fracture and tensile fracture. Most of engineering structures are usually under biaxial loading conditions, so that the influence of biaxial compressive loading on fracture analysis with constraint effects is worth paying attention. The size effect factor (relative crack length a/W, thickness to width ratio t/W and crack inclination angle β) and load factor (lateral pressure coefficient λ) of central cracked plate (CCP) specimens with I-II mixed mode crack on constraint effects under biaxial compressive loading have been investigated through theoretical analysis and finite element analysis. In-plane non-singular T-stress (T11) and its components (Tx, Ty, and Txy), out-of-plane non-singular T-stress (T33), out-of-plane constraint parameter Tz and stress triaxiality factor h have been adopted to quantify constraint effects. It demonstrates that λ has remarkable influence on SIF, T11 and T33 under biaxial compressive loading. The effect of higher a/W (long cracks) on B11 is more noticeable when I-II mixed mode crack is closer to pure mode II crack or pure mode I crack. The proportion of shear fracture increases under biaxial compression with λ. With the increase of β, B33 decreases sharply and then increases rapidly with higher λ. Tz can directly reflect stress states and adequately describe the loss of out-of-plane constraint. The stress state of crack tip is more likely to asymptotic plane-strain condition ahead of crack tip under compression. There are crucial differences in variation range and tendency of Tz subjected to biaxial tensile and biaxial compressive loading. Moreover, Tz is insensitive to λ. Stress triaxiality factor h can illustrate in-plane and out-of-plane constraint effects including size effect and load factor (sensitive to a/W, t/W, β and λ), especially can be adopted as a unified constraint parameter for long cracks under biaxial compressive loading. The in-plane T-stress components can be directly calculated by T11 under biaxial compression. The empirical equations of KII and T11 containing size effect and load factor simultaneously are effective and convenient for applications.

New Triaxial Connection Safety Factor for Tubular Design

Summary The American Petroleum Institute (API) equation for internal leak of API connections is uniaxial because it ignores axial force and external backup pressure. The ISO 13679 (2002) standard for qualification of premium connections is biaxial at best. It includes tension/compression but ignores backup pressure for both internal and external leak tests. For tubular design, this paper introduces a new fully triaxial safety factor for threaded connections with dependence on thread shear and hydrostatic pressure. Triaxial hydrostatic behavior is modeled with the mean normal stress, and thread shear behavior is modeled with the shear component of the von Mises stress. A leak line for use like the pipe body ellipse is proposed for quick leak assessment. Leak ratings and correlation with finite element analysis (FEA) results are presented for an example case of a 7-in. 35-ppf N80 long-thread-casing (LTC) connection. The new triaxial safety factor with two connection constants applies to all types of threaded connections, including tubing, casing, and drillpipe, so long as the two constants are evaluated with appropriate but simple physical tests.

Evaluation of Monkman–Grant strain as a key parameter in ductility exhaustion damage model to predict creep rupture of grade 92 steel

Conventional strain-based numerical prediction assumes that failure occurs when ductility is exhausted or accumulation of creep strain reaches the critical failure strain. Due to instability at the onset of rupture, the failure strain value appears to be scattered and leads to the erroneousness in prediction. In this paper, a new local constraint-based damage model incorporating the Monkman–Grant ductility, as a measure of strain during uniform creep deformation stage, was implemented into a Finite Element (FE) model to predict the creep damage and rupture of Grade 92 steel under uniaxial and multiaxial stress states. The prediction was applied on plain and notched bar specimens with various notch acuities. The uniaxial stress-dependent Monkman–Grant (MG) failure strain was adopted in the FE to simulate the influence of the constraints which were induced by the creep damage. The implication of reduced failure strain in long-term creep time on the rupture prediction is discussed. The multiaxial MG failure strain of the notched bar, which has a lower value than uniaxial failure strain due to the geometrical constraint, was estimated based on the linear inverse relationship between normalised MG failure strain and normalised triaxiality factor. It was found that the results obtained from the proposed technique were in good agreement with the experimental data within the scatter band of ± factor of 2. It was shown that MG failure strain can be used as an alternative to strain at fracture. MG strain outweighed strain at fracture because the determination of its value only required short-term testing to be performed. In most cases considered in the present investigation, the rupture-type fracture was predicted, however, there was evidence that under high constraint and low stress, stable crack propagation occurred before fracture. The location of the maximum creep damage was found to be dependent on the creep time, geometry or acuity level of the specimen. For sharp notch specimen, the failure was initiated near the notch root, however, as the notch radius increased, the initiation location moved further away towards the specimen centre.

Study on Influence of the Maximum Principal Stress and Stress Triaxiality Factor on Initiation Rate and on Growth Rate of the Voids of TypeIV Creep Damage in Mod.9 Cr-1Mo Steel

Study on Influence of the Maximum Principal Stress and Stress Triaxiality Factor on Initiation Rate and on Growth Rate of the Voids of TypeIV Creep Damage in Mod.9 Cr-1Mo Steel

Creep Damage Process and Rupture Time Prediction Methods of 2.25Cr-1Mo Steel Round Notch Bar Specimens

Creep damage preferentially progresses at stress concentration portion, where stress gradient exists under multiaxial stress state, in high temperature components. Therefore it is necessary to clarify creep damage evolution process and to establish a rupture time prediction method under multiaxial stress state. In this study, creep tests using plane specimens and four kinds of round notch bar specimens with different notch radius (notch tip radius 0.1mm(R0.1), 0.5mm(R0.5), 2.0mm(R2.0) and 4.0mm(R4.0)) on a 2.25Cr-1Mo steel were carried out. Rupture times of notch specimens were much longer than those of plane specimens under the same nominal stress indicating notch strengthening effect. Measured void number density on the notch root section indicated higher value at around notch surface for R0.1 and R0.5 specimens, while it was higher at around specimen center for R2.0 and R4.0. These distribution patterns corresponded to those of the maximum stress and the triaxiality factor of the notch specimens. Although, creep rupture times of notch specimens were not able to be predicted by using the stress or strain at the representative point on the notch root section, they were well predicted based on the area average damage concept, especially by considering selected damage area for R0.1 and R0.5 specimens.

Influence of Joint Arrangement on the Fracture Behavior of Lead-Free Solder Joints

The capability to standardize the fracture strength of solder joints is an effective tool to investigate the reliability of electronic devices. To achieve this purpose, in this research, the influences of joint arrangement (loading arm and load sharing) on the level of constraint imposed on joint deformation, fracture energy, and generally, fracture behavior of solder joints were investigated. Fracture behavior of solder joints using double-cantilever-beam (DCB) specimens as a function of loading arm and load sharing (i.e., the distance between two solder joints) was studied under mode I loading conditions at a strain rate of 0.03 s−1. By increasing the loading arm, the fracture force, Fci, decreased linearly, while the critical strain energy release rate for crack initiation, Jci, increased from a loading arm of 12.7 mm to 38.1 mm and then remained almost unchanged for loading arms of 38.1 mm to 71.1 mm. Plastic deformation in the solder layer and criteria such as opening stress (i.e., the predominant stress component in DCB specimen) and stress triaxiality factor were calculated. It was shown that for the larger loading arms (from 38.1 mm to 71.1 mm), the fracture behavior was as a normal DCB specimen (i.e., the normal stress caused by bending was predominant and normal stress caused by tensile loading could be ignored). For the loading arm of less than 38.1 mm, the fracture behavior was similar to that of tensile-type specimens (i.e., the normal stress caused by bending decreased significantly by decreasing the loading arm and normal stress caused by tensile loading became considerable). Variations in the distance between two solder joints did not affect the Jci value, while Fci was influenced by the joint arrangement. This behavior was attributed to stress distribution in the solder layer.

Hydrogen assisted crack initiation in metals under monotonic loading: A new experimental approach

Hydrogen is foreseen as a promising energy carrier that can control global warming by reducing CO2 emissions. However, hydrogen is associated with an embrittlement phenomenon that imparts substantial damage to the infrastructure by reducing the ductility, fracture strength, strength bearing capacity, etc., of metallic components. Therefore, understanding hydrogen-induced crack initiation mechanisms in metals are of prime importance. Greater insights into this critical phenomenon are expected if the hydrogen-induced crack initiation can be correlated with the local microstructure and corresponding stress-strain state towards their propensity for hydrogen accumulation. With this motivation, in this work, crack initiation is studied for the uncharged and hydrogen charged nickel specimens during in-situ tensile loading under the scanning electron microscope. By assuming the material to be elastic at low strains, a novel approach is implemented for generating the microstructural stress maps through strain and stiffness tensor extracted at each point in the region of interest on the specimen surface using high-resolution digital image correlation (HR-DIC) and Euler angles (given by electron backscattered diffraction data), respectively. Based on this analysis at low strain, the crack initiation sites for uncharged and hydrogen charged nickel specimens are correlated with microstructural maps of maximum Schmid factor, elastic modulus in the loading direction, hydrostatic stress, von Mises stress, and triaxiality factor. The analysis highlighted two independent factors responsible for hydrogen enhanced decohesion (HEDE) based intergranular failure observed only at the random grain boundaries, (i) strain localization due to hydrogen enhanced localized plasticity (HELP) mechanism of hydrogen embrittlement, and (ii) hydrostatic stress-based hydrogen diffusion to the crack initiation sites. These critical insights thus can help to design hydrogen embrittlement resistant metals. In addition, the novel experimental approach can be used to calibrate advance micromechanical models while providing quantitative estimate of the hydrogen distribution in realistic metallic microstructure responsible for hydrogen-assisted crack initiation with deformation.

Analysis of two parameter identification methods for original and modified Johnson-Cook fracture strains, including numerical comparison and validation of a new blue-brittle dependent fracture model for free-cutting steel 50SiB8

A non-linear relation between fracture strain and temperature is observed in Split Hopkinson Tension Bar (SHTB) tests for free-cutting steel 50SiB8 at high strains and high temperatures, due to blue-brittleness. A fourth-degree polynomial function for the thermal parts of the original and modified Johnson-Cook (JC) fracture strain constitutive equation is suggested and the corresponding parameters are identified. Fracture modelling of 50SiB8 is not reported in literature. 50SiB8 is characterized under quasi-static, isothermal, high temperature and high strain rate conditions using smooth and notched tension specimens. For the calculation of the original and modified JC fracture parameters, two different parameter identification procedures, so-called forward and backward parameter identification methods are performed, compared with each other and explained in detail. For the stress triaxiality factor of the original and modified JC fracture model, the forward parameter identification method is suggested for the original JC fracture model, while backward parameter identification method is proposed for the modified JC fracture model. The effect of blue-brittleness in the temperature factor and the corresponding parameters are presented. Furthermore, FEM simulations of the original and the blue-brittleness based JC fracture model are compared with experiments. In the blue-brittle temperature range, the new adjusted JC model shows more accurate results, regarding fracture diameter and strain. Additionally, this work introduces a fracture model combining the Bai-Wierzbicki stress triaxiality dependent model, JC fracture models and the nonlinear temperature factor with blue-brittleness effect, while further experiments are required in order to determine its parameters.