@article { author = {Moazam, M. A. and Ghasemi, A. and Moradi, M. and Monajatizadeh, H.}, title = {Pattern of Residual Stress in Rail by FEM Analysis and Strain Gage Sectioning Technique}, journal = {Iranian Journal of Materials Forming}, volume = {2}, number = {1}, pages = {1-10}, year = {2015}, publisher = {Shiraz University}, issn = {2383-0042}, eissn = {2383-0042}, doi = {10.22099/ijmf.2015.2910}, abstract = {Final step of rail manufacturing is cold rolling straightening process and it hassignificant effects on mechanical properties, straightness, flatness and development of residualstresses. Measurement of residual stresses after straightening process is obligated by railmanufacturing standards. In the present investigation, an attempt has been made to evaluateresidual stresses after straightening process by finite element method and strain gage sectioningtechnique. The straightening process has been simulated here using the FE package ABAQUS. Allthe input data were extracted from experimental tests according to rail manufacturing standard andhomogenous and isotropic behavior of material were considered. Moreover, initial camber of therail was measured after hot rolling and cooling process. Obtained results of numerical calculationhas been validated by strain gage sectioning technique and compressive residual stresses in headand web and tension residual stress in foot of the rail has been observed. The roller arrangementused in this investigation could reduce the amount of residual stresses comparing with the previousresults. Furthermore, straightness of the rail after straightening was satisfactory.}, keywords = {Rail,Straightening process,Camber,Numerical calculation,Strain gage}, url = {https://ijmf.shirazu.ac.ir/article_2910.html}, eprint = {https://ijmf.shirazu.ac.ir/article_2910_0f289ca2a35103233813b046da754f61.pdf} } @article { author = {Nayebi, A. and Khosravi, A.H.}, title = {Evaluation of Effective Paramters on Formability of TWB}, journal = {Iranian Journal of Materials Forming}, volume = {2}, number = {1}, pages = {11-17}, year = {2015}, publisher = {Shiraz University}, issn = {2383-0042}, eissn = {2383-0042}, doi = {10.22099/ijmf.2015.2911}, abstract = {Formability of automotive friction stir welded TWB (tailor welded blank) sheets isnumerically investigated in biaxial stretching based on hemispherical dome stretch (HDS) test infour automotive sheets of Aluminum alloy 6111-T4, 5083-H18, 5083-O and DP590 steel, havingdifferent thicknesses. The effects of the weld zone modeling and the thickness ratio on formabilityare evaluated. In order to carry out the numerical simulations, mechanical properties areconsidered according to Chung et al. [11] experimental results. von-Mises and Hill’48 quadraticyield functions are used to compare the isotropic and anisotropic behaviors of the used sheets. Inorder to simplify the problem, the anisotropy of the weld zone is ignored. The FEM results arecompared with experimental results of [11]. Anisotropic assumption for base materials and varyingthickness for the weld zone give more accurate prediction. Numerical results are in goodagreement with the experimental results. Failure onset locations and patterns are accurate. Sincethe formability is dependent on the stress concentration, asymmetric distribution of strength andcomplexity of weld zone properties, the thickness ratio in TWB affect formability.}, keywords = {TWB,HDS, Anisotropic, Forming, FSW}, url = {https://ijmf.shirazu.ac.ir/article_2911.html}, eprint = {https://ijmf.shirazu.ac.ir/article_2911_290130a3fec613fa587f66224b03342c.pdf} } @article { author = {Seyed Salehi, M. and Anjabin, N. and Mansoori, R.}, title = {Hot Deformation Behavior of Ni80A Superalloy During Non-Isothermal Side Pressing}, journal = {Iranian Journal of Materials Forming}, volume = {2}, number = {1}, pages = {18-29}, year = {2015}, publisher = {Shiraz University}, issn = {2383-0042}, eissn = {2383-0042}, doi = {10.22099/ijmf.2015.2912}, abstract = {In the present study, the microstructural changes of a Nickel based superalloy Nimonic80A during a non-isothermal deformation were studied. Therefore, microstructure evolutionduring hot side pressing test was predicted with combined methods of finite element analysis andprocessing map of the material. The predicted results were validated through experimentalmicrostructural studies. The results show that the distribution of deformation parameters (i.e.strain, strain rate, and temperature) is non-uniform in the deformed samples. The severity of thisnon-uniformity depends on the amount of sample reduction. High reduction value at one stepforging can cause flow localization and non-uniform dynamic recrystallization, which results theformation of adiabatic shear bands, while using the lower reduction value at each forging step,leads to more uniformly distribution of the deformation parameters and thus uniform the dynamicrecrystallization with the stable flow. Hence the workability and microstructure of the Nimonic80A alloy are mainly depends on the deformation path.}, keywords = {Hot deformation,Nimonic 80A,Processing map,Microstructure,Finite Element Analysis}, url = {https://ijmf.shirazu.ac.ir/article_2912.html}, eprint = {https://ijmf.shirazu.ac.ir/article_2912_c18d7ddc209e86bb62094a0b09e45ab3.pdf} } @article { author = {Khamei, A.A. and Dehghani, K. and Bakhshi, S. and Kalayeh, K.}, title = {Hot and Cold Tensile Behavior of Al 6061 Produced by Equal Channel Angular Pressing and Subsequent Cold Rolling}, journal = {Iranian Journal of Materials Forming}, volume = {2}, number = {1}, pages = {30-42}, year = {2015}, publisher = {Shiraz University}, issn = {2383-0042}, eissn = {2383-0042}, doi = {10.22099/ijmf.2015.2913}, abstract = {The full annealing AA6061 aluminum alloy was subjected to severe plastic deformationvia the combination of equal channel angular pressing (ECAP) and cold rolling (CR) in order torefine its microstructure and to improve its mechanical properties. According to the results of hotand cold tensile tests, the combination of ECAP and CR significantly affected the final strengthand ductility of studied AA6061. Four passes of ECAP followed by 90% reduction in rolling led toabout 5.4 and 3.15 times increase in the yield and ultimate tensile strengths, respectively. Inaddition, the hot ductility and strain rate sensitivity were increased by applying ECAP plus CR.The changes in mechanical properties were attributed to the enhanced dislocation density and tothe reduced grain size. The results show that a decrease in grains/subgrains size (0.37 μm) and anincrease in the fraction of high angle grain boundaries, exhibited significant effect on the hotductility of higher severe plastic deformed sample.}, keywords = {severe plastic deformation,Ultrafine-Grained (UFG),6061 Al alloy,Rolling,Hot ductility}, url = {https://ijmf.shirazu.ac.ir/article_2913.html}, eprint = {https://ijmf.shirazu.ac.ir/article_2913_7e7230f408c8744c98320ee4cc373d87.pdf} } @article { author = {Ebrahimi, G. R. and Momeni, A. and Eskandari, H.}, title = {Interaction Between Precipitation and Dynamic Recrystallization in HSLA-100 Microalloyed Steel}, journal = {Iranian Journal of Materials Forming}, volume = {2}, number = {1}, pages = {43-50}, year = {2015}, publisher = {Shiraz University}, issn = {2383-0042}, eissn = {2383-0042}, doi = {10.22099/ijmf.2015.2914}, abstract = {Strain induced precipitation in HSLA-100 steel was investigated by conducting hotcompression and relaxation tests at temperature range of 850°C to 1100°C and strain rate of 0.001s-1 to 1s-1. The absence of dynamic recrystallization at temperatures below 1000°C was attributedto the influence of dynamic precipitation. The stress relaxation tests showed that strain inducedprecipitation is possible over a wide range of temperatures from 850°C to 1050°C. The startingand finishing times of precipitation were sensitive to temperature than strain rate. At temperaturerange of 950-1000°C and strain rate of 0.1s-1 the lowest times for precipitation were observed. Thecombination of precipitation-time-temperature and recrystallization-time temperature diagramsshowed that at high temperatures and low strain rates, precipitation precedes dynamicrecrystallization, whereas at the opposite condition, dynamic recrystallization goes in advance. Thestarting and finishing times for dynamic precipitation were approximated about 40 percent lowerthat those for strain induced precipitation.}, keywords = {Hot deformation,Cu-bearing HSLA steel,Dynamic recrystallization,Hot compression,Stress relaxation}, url = {https://ijmf.shirazu.ac.ir/article_2914.html}, eprint = {https://ijmf.shirazu.ac.ir/article_2914_a7dd99507bc8df3c14ac328d77cfa8bc.pdf} } @article { author = {Khosravifard, A. and Moshksar, M. M. and Ebrahimi, R.}, title = {Stacking Fault Energy and Microstructural Insight into the Dynamic Deformation of High-Manganese TRIP and TWIP Steels}, journal = {Iranian Journal of Materials Forming}, volume = {2}, number = {1}, pages = {51-61}, year = {2015}, publisher = {Shiraz University}, issn = {2383-0042}, eissn = {2383-0042}, doi = {10.22099/ijmf.2015.2915}, abstract = {The dynamic behavior of three high manganese steels with very different stacking faultenergy (SFE) values (4-30 mJ/m2) were studied using high strain rate torsional tests. The hotrolledmicrostructure of the steel with the lowest SFE of 4 mJ/m2 consisted of a duplex mixture ofaustenite and ε-martensite, but those of the other two steels were fully austenitic. The deformedmicrostructures were studied by optical and electron microscopy. The quasi-static deformation ofthe low-SFE steel was accompanied with profuse martensitic transformation. However, when thissteel was deformed at high strain rates (> 500 /s), martensite formation was reduced due to theadiabatic temperature rise and the increased SFE of the steel. The deformation of the steel withmoderate SFE of 18 mJ/m2 at all the tested strain rates was mainly controlled by the formation ofmechanical twins that was leading to an excellent ductility of about 55% even at the highest strainrate of ~1700 /s. In contrast, dynamic deformation of the steel with the highest SFE of 30 mJ/m2led to the appearance of some shear bands. This was ascribed to the decreased twinning and workhardening rate in this steel. Finally, the topographic studies showed that the fracture surface of thelow-SFE steel contained relatively larger cleavage areas and smaller dimples suggesting arelatively more brittle fracture. This was related to the presence of brittle ε and α` martensitephases in this steel.}, keywords = {Stacking fault energy,High Manganese,TRIP,TWIP,High strain rate}, url = {https://ijmf.shirazu.ac.ir/article_2915.html}, eprint = {https://ijmf.shirazu.ac.ir/article_2915_6ec3ad4682f996d7b7cfcf11543bcf78.pdf} }