Utafiti huu umechunguza jinsi heat-treatment conditions za bainitic steel zinavyobadilisha transformation kinetics, microstructure form, transformation-induced internal stresses na mechanical behavior kwa kuunganisha experiments na three-dimensional phase-field simulations. Laboratory steel yenye composition ya Fe–0,19C–1,48Si–2,38Mn weight percent ilishikiliwa isothermally kwa dakika 45 katika 673 K au 723 K baada ya austenitization. Katika experiments, treatment ya 673 K ilitoa finer bainitic ferrite na yield strength ya 765 ± 5 MPa, huku treatment ya 723 K ikitoa thicker ferrite na yield strength ya 667 ± 5 MPa. Phase-field model ilireproduce temperature trend hii na general ordering ya experimental tensile curves, lakini ili-overestimate bainitic ferrite thickness katika temperatures zote mbili. Multiaxial yielding behavior ilikadiriwa kwa Barlat91 model, lakini only uniaxial tensile response katika x direction ndiyo ilijaribiwa experimentally.

Kulingana na model results, lower holding temperature hutoa larger undercooling na stronger transformation driving force. Kuongeza heat-extraction coefficient kutoka 0,25 s⁻¹ hadi 0,5 s⁻¹ huharakisha cooling na transformation, huacha muda mchache wa mechanical relaxation na kuzalisha higher transformation-induced internal stresses. Largest model yield surface ilipatikana katika 673 K na 0,5 s⁻¹. Hata hivyo, simulations zilizotumia 0,25 s⁻¹ zilionyesha agreement iliyo karibu zaidi na experimental tensile curves. Kwa hiyo highest model strength na thermal path iliyo karibu zaidi na experiment si condition ile ile.

Kwa mtazamo wa Uturuki: Approach ya study inaweza kutumika nchini Uturuki katika automotive sheets, railway steels, gear na bearing materials, heavy-machinery components, wear-resistant steels na heat-treatment design. Domestic steel producers na research centers zinaweza kuvalidate phase-field models kwa different alloy compositions kupitia dilatometer, SEM/EBSD, X-ray diffraction, hardness na multidirectional mechanical tests, kisha kuendeleza heat-treatment windows kwa fewer trial productions. Hata hivyo, current results zimewekewa kikomo na single laboratory composition, two isothermal temperatures na uniaxial-tension validation. Strength, fatigue life, weldability, production cost au industrial-furnace performance ya specific steel grade produced in Turkey haiwezi kutolewa moja kwa moja kutoka study hii.

Main problem ya research ni nini?

Bainitic steels zina thamani katika automotive, railway, aerospace na heavy-engineering applications kwa sababu zinaweza kuunganisha high strength, fracture toughness na wear resistance katika same microstructure. Lakini “bainite” si uniform phase. Kutegemea heat-treatment conditions, bainitic ferrite plates zinaweza kubadilika katika:

• Thickness,
• Length,
• Orientation,
• Variant distribution,
• Amount of retained austenite between them,
• Local internal stresses zinazozalishwa

. Features hizi zinaathiri si uniaxial yield strength pekee, bali pia plastic behavior chini ya tensile, compressive na shear loads zinazotumika kutoka different directions.

Main research question inaweza kufupishwa hivi: Holding temperature na intensity of heat transfer to surroundings zinabadilishaje bainitic transformation; resulting three-dimensional microstructure, internal stress na crystal orientations zinaathirije mechanical strength na anisotropic yield surface?

Process–microstructure–property chain iliyopendekezwa na study

Watafiti walijaribu kuunda relationship hii:

Heat-treatment condition → temperature history → austenite-to-bainite transformation kinetics → bainitic ferrite morphology and retained austenite → transformation-induced internal stresses → tensile behavior and multiaxial yield surface.

First part ya chain iliwakilishwa kwa phase-field model, mechanical part kwa crystal plasticity, na macroscopic anisotropic yield behavior kwa Barlat91 phenomenological yield criterion.

Experimental steel ilitengenezwaje?

Laboratory ingot yenye uzito wa takriban 80 kg ilitengenezwa katika vacuum induction furnace. Initial cross-section ya ingot ilikuwa 140 × 140 mm². Material ilihomogenizeiwa katika 1200 °C, kisha ikaforgiwa kuwa billets zenye 60 × 60 mm² cross-section. Second homogenization ilidumu saa five na ikafuatiwa na furnace cooling.

Composition ilibainishwa kwa optical emission spectroscopy, huku carbon content ikibainishwa kwa combustion analysis.

Heat treatment ilifanywaje?

Samples ziliaustenitizeiwa katika salt bath kwa sekunde 300, katika temperature ya 60 K juu ya A_c3. Source haitoi exact A_c3 value. Baada ya fully austenitic structure kupatikana, samples zilihamishwa haraka kwenda second salt bath.

Two isothermal treatments zilitumika:

• Holding katika 673 K kwa dakika 45,
• Holding katika 723 K kwa dakika 45.

Baada ya holding, samples ziliquenchiwa kwa maji hadi room temperature. Bainitic-ferrite-based microstructure iliundwa katika treatments zote mbili. Experimental images zinaonyesha ferrite plates formed at 673 K ni thinner kuliko zilizoundwa at 723 K.

Experimental microstructure ilichunguzwaje?

Sample surfaces zilisagwa hadi 1200-grit SiC paper, zikapolishwa kwa 6 na 1 µm diamond paste na kuetched kwa %3 Nital. Secondary electron images zilipatikana kwenye field-emission Zeiss Sigma microscope kwa kutumia:

• 30 µm aperture,
• 15 kV accelerating voltage,
• 9 mm working distance

.

Figure 5 ya study inaonyesha “inverse pole figure maps” kwa samples za 673 na 723 K. Orientation maps za aina hii kwa kawaida hutegemea electron backscatter diffraction data; lakini katika version hii EBSD instrument, step size, indexing rate na data-cleaning procedures hazijaelezwa.

Phase-field model inawakilisha nini?

Katika phase-field method, kila phase au crystal variant inawakilishwa kwa continuous field variable inayobadilika kwa space na time. Badala ya kufuatilia sharp boundary moja kwa moja, boundary kati ya phases huresolveiwa kama transition region yenye finite thickness.

Temporal change ya phase fields imeelezwa kwa multiphase kinetic equation hii:

\[ \dot{\phi}_{\alpha}(\mathbf{x},t) = -\frac{1}{N} \sum_{\beta\neq\alpha} M_{\alpha\beta} \left( \frac{\delta F}{\delta\phi_{\alpha}} - \frac{\delta F}{\delta\phi_{\beta}} \right). \]

Hapa \(\phi_{\alpha}\) ni field variable ya particular phase au variant, \(M_{\alpha\beta}\) ni interface mobility, na \(F\) ni total free energy.

Total free energy imefafanuliwa kama:

\[ F=\int_{\Omega} \left( f_{\mathrm{chem}}+ f_{\mathrm{int}}+ f_{\mathrm{el}} \right)d\Omega \]

. Three main contributions ni:

• Chemical energy: Thermodynamic driving force inayowezesha phase transformation,
• Interface energy: Cost ya kuunda phase na variant boundaries,
• Elastic energy: Mechanical energy inayotokana na transformation strain na lattice mismatch.

Carbon transport ilishughulikiwaje?

Local carbon concentration ilisolveiwa kwa diffusion equation:

\[ \dot{c}= \nabla\cdot \left[ \sum_{\alpha}\phi_{\alpha}D_{\alpha}\nabla c_{\alpha} + \sum_{\alpha,\beta}J_{\alpha\beta} \right]. \]

\(D_{\alpha}\) inawakilisha diffusion coefficient matrix ya kila phase, na \(J_{\alpha\beta}\) ni anti-trapping flux inayotumiwa kupunguza artificial solute trapping inayoweza kutokea katika diffuse-interface approach.

Phase-field na diffusion equations zilidiscretizeiwa kwenye regular grid kwa finite-difference method, na time integration ikafanywa kwa explicit forward Euler method.

Transformation-induced stresses zilihesabiwaje?

Model ilitenganisha elastic, plastic na transformation components multiplicatively chini ya finite deformation:

\[ \mathbf{F} = \mathbf{F}^{el} \mathbf{F}^{pl} \mathbf{F}^{tr}. \]

Hapa:

• \(\mathbf{F}^{el}\), elastic deformation gradient,
• \(\mathbf{F}^{pl}\), plastic deformation gradient,
• \(\mathbf{F}^{tr}\), deformation gradient inayotokana na phase transformation.

Elastic strain ilihesabiwa kwa Green–Lagrange measure na St. Venant–Kirchhoff hyperelastic approach. Mechanical equilibrium problem ilisolveiwa kwa fast-Fourier-transform-based spectral solver.

Crystal plasticity model

Plastic deformation iliwakilishwa kama sum ya active slip systems ndani ya crystal:

\[ \mathbf{L}^{p} = \sum_{s=1}^{N} \dot{\gamma}^{s} \mathbf{m}^{s}\otimes\mathbf{n}^{s}. \]

\(\dot{\gamma}^{s}\) inaonyesha slip rate ya corresponding slip system, \(\mathbf{m}^{s}\) slip direction, na \(\mathbf{n}^{s}\) normal ya slip plane.

Slip rate ilitolewa kwa power law inayotegemea resolved shear stress:

\[ \dot{\gamma}^{s} = \dot{\gamma}_{0} \left| \frac{\tau^{s}}{\tau_{c}^{s}} \right|^{n} \mathrm{sgn}(\tau^{s}). \]

Change ya slip resistance kwa plastic deformation ilihesabiwa kwa hardening law. Study inaeleza wazi kwamba phenomenological crystal-plasticity model iliyotumika haitoki directly kwa temperature.

Heat extraction na latent heat zilimodeliwaje?

Sample temperature ilihesabiwa kwa extended form ya Newton cooling law yenye transformation latent heat:

\[ \dot{T}(t) = -r\left[T(t)-T_s\right] + \frac{Q}{\rho C_p}\dot{f}. \]

Hapa:

• \(T\), sample temperature,
• \(T_s\), cooling-medium au bath temperature,
• \(r\), heat-extraction coefficient,
• \(Q\), latent heat ya bainitic transformation,
• \(\rho\), density,
• \(C_p\), specific heat,
• \(\dot{f}\), rate of change ya transformed phase-volume fraction.

Latent heat inayotolewa wakati wa transformation inaweza temporarily kupunguza cooling au kuunda small reheating. Plateau au rise karibu na sekunde fifth katika Figure 3 imeelezwa kwa effect hii.

Three-dimensional simulation setup

Figure 2 inaonyesha three-dimensional microstructures kwa kila thermal condition. Different colors zinawakilisha 24 Kurdjumov–Sachs bainitic-ferrite variants, huku black regions zikiwakilisha retained austenite.

Temperature curves zilionyesha nini?

All four calculations zilianza kutoka 900 K. Kama ilivyotarajiwa, 673 K bath conditions zilifikia lower final temperature. Kwa same bath temperature:

• \(r=0{,}5\ \mathrm{s}^{-1}\) ilitoa faster initial cooling,
• \(r=0{,}25\ \mathrm{s}^{-1}\) ilitoa longer transient cooling process

.

Bath temperature ilitafsiriwa kama main variable inayobainisha final thermal level, huku heat-extraction coefficient ikibainisha rate ya kufikia level hiyo.

Bainitic ferrite volume fraction

Katika Figure 4, bainitic-ferrite volume fraction iliongezeka temperature iliposhuka. 673 K conditions zilifikia higher final bainitic-ferrite fraction ndani ya simulation time kuliko 723 K conditions.

Heat-extraction coefficient haikubadilisha final phase fraction kwa nguvu sawa na temperature, lakini iliathiri kwa kiasi kikubwa how fast transformation occurred na resulting morphology. 723 K na 0,25 s⁻¹ condition ilitoa lowest final bainitic-ferrite fraction.

Experimental na calculated ferrite thickness

Experiment na simulation zilionyesha same trend: bainitic ferrite huwa thicker holding temperature inapoongezeka. Hata hivyo calculated values ni larger kwa absolute terms. Difference ni wazi hasa katika 673 K.

Watafiti waliunganisha deviation hii na model resolution na limitation ya image-based thickness determination. Katika simulation statistics, ferrite thickness iliwakilishwa na takriban pixels 6–7, kwa hiyo small differences zinaweza kubaki ndani ya grid uncertainty.

Area, length na shape statistics

Figure 6 inalinganisha distributions za area, aspect ratio, length na thickness. Kulingana na source interpretation:

• 673 K na 0,5 s⁻¹ zilitengeneza largest area na longest bainitic features.
• 673 K conditions zilihusishwa na more elongated features.
• 723 K conditions zilionyesha shorter na more compact features.
• Katika 723 K na 0,25 s⁻¹, prolonged thermal exposure ilitoa muda zaidi wa lateral growth na coarsening.
• Differences katika thickness distributions hazikuweza kutenganishwa reliably kwa sababu ya grid resolution.

Hapa “larger area au length” na “thicker ferrite” si metric moja. Katika 673 K na rapid heat extraction, features zinaweza kuwa longer na elongated huku plate thickness ikitarajiwa kuwa physically thinner.

Area na length distributions zilitolewa kutoka simulation images pekee. Experimental area na length distributions za comparison hazipo katika study.

Transformation-induced internal stresses

Figure 7 inaonyesha local von Mises stress distributions baada ya heat-treatment conditions nne. Stresses si homogeneous ndani ya microstructure; zinaconcentrate katika specific ferrite plates, variant boundaries na mechanical-incompatibility regions.

Highest local stresses zilihesabiwa katika 673 K na 0,5 s⁻¹. Fast transformation huleta transformation strain ndani ya short time na huacha less time for plastic relaxation. Slower heat extraction hutoa longer time for mechanical accommodation.

Scale kwenye figure ni takriban kutoka 3,3 × 10⁷ hadi 1,3 × 10⁹ Pa. Values hizi si macroscopic tensile stress bali local constrained stresses ndani ya computational volume. Kwa kuwa model haijumuishi cracking, damage na all stress-relief mechanisms, absolute peak values hazipaswi kutafsiriwa kama stress inayopimika moja kwa moja katika real part.

Tensile tests

Uniaxial tensile tests zilifanywa kwenye B5×25 cylindrical specimens:

• Gauge diameter: 5 mm,
• Gauge length: 25 mm,
• Test temperature: room temperature,
• Strain rate: 0,001 s⁻¹,
• Machine: ZwickRoell Z100 electromechanical universal testing machine.

673 K treatment ilitoa yield strength takriban 98 MPa higher kuliko 723 K. Watafiti waliunganisha difference hii na higher bainitic-ferrite fraction, finer ferrite structure na stronger transformation driving force inayotokana na lower temperature.

Number of test repetitions, kama ±5 MPa ni standard deviation au another uncertainty measure, na offset method iliyotumika kubainisha yield strength hazijaelezwa katika source.

Experimental na calculated tensile curves

Figure 8 inalinganisha experimental curves na simulation curves nne. Model ilireproduce kwamba sample ya 673 K inabeba higher stress kuliko sample ya 723 K kwa heat-extraction coefficients zote mbili.

Curves zilizotumia \(r=0{,}25\ \mathrm{s}^{-1}\) zilitoa results zilizo karibu zaidi na experiments. Kwa upande mwingine, simulations zilizotumia \(r=0{,}5\ \mathrm{s}^{-1}\) zilipredict higher strength. Source inaeleza hii kwa:

• Faster transformation,
• Finer ferrite formation,
• More microstructural obstacles to plastic flow,
• Higher residual internal stress

.

Barlat91 yield surface inaonyesha nini?

Katika uniaxial tension, yielding inaweza kuonyeshwa kwa single stress value. Katika multiaxial stress states, yield surface inayotenganisha elastic na plastic regions inahitajika.

Study ilitumia Barlat91 criterion inayoweza kuwakilisha six stress components na anisotropic behavior. General form ya model:

\[ \Phi=2\sigma_y^n \]

imefafanuliwa, kwa kutumia second na third stress invariants pamoja na six anisotropy parameters. Source inasema \(n=6\) kwa BCC materials na \(n=8\) kwa FCC materials. Haijaelezwa wazi ni \(n\) value gani ilitumika katika final Barlat91 fit kwa multiphase bainitic-ferrite–retained-austenite structure.

Kwanza tensile behavior katika x direction ilitathminiwa relative to experimental curve. Kisha additional tension–compression na shear-dominated loading paths zilitumika numerically kwa same crystal-plasticity parameters. Numerical yield points hizi zilitumika kubainisha Barlat91 surface.

Main result ya yield surfaces

Surfaces katika Figure 11 si circular. Hii inaonyesha microstructure inatoa direction-dependent plastic response ambayo haiwezi kuwakilishwa kikamilifu na isotropic von Mises criterion.

General ordering ya yield-surface size ni:

1. 673 K, 0,5 s⁻¹: largest surface na highest model yield resistance,
2. 723 K, 0,5 s⁻¹,
3. 673 K, 0,25 s⁻¹,
4. 723 K, 0,25 s⁻¹: smallest surface.

Lower temperature na faster heat extraction zilipanua yield surface outward kupitia higher transformation driving force, faster microstructure formation na higher internal stresses.

Kwa nini yielding behavior ni anisotropic?

Study inaunganisha anisotropy na microstructural factors nne:

• Directional na elongated form ya bainitic ferrite plates,
• Unequal volume fractions za 24 Kurdjumov–Sachs variants,
• Variant-dependent transformation strains,
• Heterogeneous residual stresses ndani ya microstructure.

Load inapowekwa parallel, perpendicular au katika shear direction relative to ferrite plates, different slip systems na phase-boundary constraints zinaweza kuactivate. Kwa hiyo yield resistance inategemea si total ferrite fraction pekee, bali pia loading direction.

Kwa nini temperature effect ilipungua katika shear-dominated loading?

Katika baadhi ya shear-dominated regions za yield surface, 673 na 723 K curves zilikaribiana. Watafiti wanaeleza hii kwa shear loading kuactivate broader group ya crystal orientations na kupunguza effect ya one dominant morphological direction.

Hasa katika 0,5 s⁻¹, similar volume fractions za certain Kurdjumov–Sachs variants numbered 2, 4, 9, 10, 13, 15, 20 na 23 zinaweza kuchangia convergence ya collective response katika shear direction. Explanation hii ni model-based interpretation na haikujaribiwa kwa multiaxial experiment.

Strengths za study

• Laboratory steel ilitengenezwa na chemical composition ikapimwa.
• Two controlled isothermal bainite treatments zilitumika.
• Microstructure na uniaxial tensile behavior zilichunguzwa experimentally.
• Phase transformation, carbon diffusion, latent heat na mechanical interaction ziliunganishwa katika one framework.
• Three-dimensional microstructure iliwakilisha 24 crystal variants na retained austenite.
• Simulation overestimation ya ferrite thickness iliripotiwa wazi.
• Local internal stresses zilielezwa kutokuwa macroscopic tensile stress.
• Transition kutoka uniaxial validation hadi multiaxial prediction ilielezwa kuwa model-based.
• Integrated link kati ya heat treatment, microstructure na yield surface iliwekwa.

Limitations za study

• Study haijapitia peer review.
• Only one steel composition ilichunguzwa.
• Only 673 na 723 K isothermal holding temperatures zililinganishwa experimentally.
• Simulation ili-overestimate bainitic ferrite thickness quantitatively.
• Simulated area na length distributions hazikuvalidateiwa experimentally.
• Internal stresses hazikupimwa kwa X-ray, neutron diffraction au microstrain method.
• Damage, cracking na fracture mechanisms hazikuingizwa katika model.
• Only uniaxial tensile response katika x direction ilitathminiwa experimentally.
• Multiaxial yield surfaces na shear response hazikuvalidateiwa experimentally.
• Number of tensile-test repeats na uncertainty calculation hazijaelezwa.
• Details za EBSD au inverse-pole-figure map production hazijatolewa.
• Full numerical values za Barlat91 parameters na inverse-identification details hazijawasilishwa.
• Units za stress na hardening parameters katika Table 5 zinaonekana inconsistent.
• Time step, total computation time, hardware na convergence study kwa phase-field calculations hazijaripotiwa.
• Hakuna open repository link ya data na code iliyotolewa.

Study inaunga mkono nini?

• Lower isothermal temperature inahusishwa na finer bainitic ferrite na higher yield strength katika steel hii.
• Phase-field model inaweza qualitatively capture temperature-dependent ferrite-thickness trend.
• Heat-extraction coefficient inaweza kuathiri transformation rate na internal-stress development.
• Fast transformation inaweza kuzalisha higher local transformation stresses.
• 673 K treatment ilitoa higher experimental yield strength kuliko 723 K treatment.
• Phase-field/crystal-plasticity model ilireproduce experimental uniaxial strength ordering.
• Simulated bainitic microstructure inaonyesha direction-dependent yielding behavior.
• Barlat91 inaweza kuwakilisha anisotropic yield points zinazopatikana kutoka model kwa macroscopic surface.

Study haithibitishi nini?

• Haithibitishi kwamba 673 K na 0,5 s⁻¹ ni overall best heat treatment katika real production.
• Haionyeshi kwamba calculated local internal stresses zina same magnitude katika real steel.
• Haivalidate multiaxial yield surfaces experimentally.
• Haithibitishi kwamba model inaweza kuhamishwa directly kwa other steel compositions.
• Haionyeshi kwamba higher tensile strength itatoa higher toughness, fatigue life au wear resistance.
• Haifuatilii experimentally transformation ya retained austenite kwenda martensite wakati wa deformation.
• Haisolve industrial-scale temperature gradients, part geometry au furnace variability.
• Haithibitishi kwamba Barlat91 ni experimentally superior to von Mises, Hill48 au other criteria.

Maana kwa engineering

Most important contribution ya study ni kujaribu kusolve intermediate microstructural mechanisms badala ya kuunganisha heat-treatment temperature tu na final hardness au tensile strength. Framework kama hii ikiendelezwa, manufacturer anaweza kuscreen numerically kabla ya kujaribu physically kila possible heat treatment:

• Bainite transformation rate,
• Ferrite thickness na orientation,
• Retained-austenite distribution,
• Local internal-stress regions,
• Yield resistance katika different loading directions

.

Hata hivyo study hii bado si fully industrial “virtual materials laboratory”. Absolute microstructure dimensions, multiaxial mechanical response na local stresses zinahitaji broader experimental validation.

Mbinu na Matokeo ya Utafiti

Technical summary ya research design

Main quantitative findings

• Experimental bainitic-ferrite thickness katika 673 K ni 0,15 ± 0,05 µm.
• Experimental bainitic-ferrite thickness katika 723 K ni 0,26 ± 0,08 µm.
• 673 K phase-field result ni 0,341 µm.
• 723 K phase-field result ni 0,382 µm.
• Experimental yield strength katika 673 K ni 765 ± 5 MPa.
• Experimental yield strength katika 723 K ni 667 ± 5 MPa.
• Lower-temperature treatment ilitoa approximately 98 MPa higher experimental yield strength.
• Simulations zilizotumia 0,25 s⁻¹ zilitoa results zilizo closest to experimental tensile curves.
• Simulations zilizotumia 0,5 s⁻¹ zilitoa higher model strength na higher internal stress.
• Largest calculated yield surface ni ya 673 K na 0,5 s⁻¹.
• Upper scale katika internal-stress maps ni takriban 1,3 GPa; hii ni local model stress.

Scientific function ya figures

Technical inconsistencies ndani ya source

• Katika Table 5, units za stress parameters pamoja na numerical values zilizotolewa zinatoa physically unusual magnitudes.
• Hardening equations zinatumia exponent \(a\), huku Table 5 ikitoa “Hardening Index m”; relationship kati ya symbols mbili haijaelezwa.
• Separate \(n\) values zimetolewa kwa BCC na FCC katika Barlat91, lakini selected value katika macroscopic fit ya two-phase microstructure haijaripotiwa.
• EBSD experimental conditions za inverse pole figure maps hazijatolewa.
• Ingawa title inasisitiza experimental validation, multiaxial yield behavior ni model-based, si experimental.

Careful interpretation ya findings

Study inaonyesha effect ya heat-treatment temperature kwenye experimental microstructure thickness na uniaxial yield strength kwa reliable trend level. Phase-field model inareproduce trend hii, lakini haijafikia quantitative accuracy katika absolute ferrite thickness.

Internal-stress na multiaxial-yield-surface results zina thamani kwa kuchunguza physical mechanisms na kudesign new experiments. Hata hivyo, kwa kuwa hazikupimwa directly, zinapaswa kutazamwa kama model predictions zinazohitaji experimental testing, si validated material data.

Dokezo la Chanzo na Mbinu

Full original title ya study: Experimentally validated process–microstructure–property relations of bainitic steels derived from phase-field simulations

Authors: Dhanunjaya Kumar Nerella, Muhammad Adil Ali, Oguz Gulbay, Oleg Shchyglo na Ingo Steinbach.

Author order: Imehifadhiwa kama ilivyotolewa katika source.

Co-first author: Hakuna equal contribution au co-first authorship information iliyotolewa.

Corresponding author: Dhanunjaya Kumar Nerella.

Contact address: Uploaded text haina email address. Official Ruhr University Bochum researcher record inatoa `dhanunjaya.nerella@rub.de`.

Institution 1: Interdisciplinary Centre for Advanced Materials Simulation, Ruhr University Bochum, Universitätsstraße 150, 44801 Bochum, North Rhine-Westphalia, Germany.

Institution 2: Steel Institute, RWTH Aachen University, Intzestraße 1, 52072 Aachen, North Rhine-Westphalia, Germany.

DOI:10.2139/ssrn.7176521

Official source link:Official SSRN record page

Publication platform: SSRN.

Submission date: 3 Julai 2026.

Publication year: 2026.

Journal: Hakuna specific journal name au acceptance information katika version hii.

Publisher: Text ina phrase “Preprint submitted to Elsevier”; hata hivyo hakuna specific Elsevier journal au accepted publication record iliyotambuliwa.

Source type: Preprint research article inayounganisha experimental heat treatment, microstructure characterization na tensile testing na three-dimensional phase-field, crystal-plasticity na phenomenological yield-surface modeling.

Peer-review status: Study haijapitia peer review.

Author contributions: Version hii haina separate CRediT au task-based author-contribution statement.

Funding: Research iliungwa mkono na Germany Federal Ministry of Research, Technology and Space chini ya DiStEL project, project number 13XP5226E.

Conflict of interest: Hakuna separate conflict-of-interest au competing-interests statement katika version hii.

Data access: Phase-field simulation data zimesemwa kuwa available from authors upon reasonable request. Hakuna open-data repository link iliyotolewa.

Code access: Source code, software version iliyotumika, run scripts au reproduction package hazikushirikiwa.

Experimental-validation boundary: Experimental comparison imewekewa kikomo na microstructure-thickness trend na uniaxial tensile response katika x direction. Internal stresses, other loading directions na Barlat91 multiaxial surfaces ni model-based predictions.

Morphology-validation boundary: Phase-field model ilicapture temperature-dependent thickening trend lakini ili-overestimate ferrite thickness hasa katika 673 K. Simulated area na length distributions hazikulinganishwa na experimental data.

Source-consistency warning: Stress na hardening units katika crystal-plasticity parameter table zinatoa magnitudes zinazohitaji explanation. Barlat91 exponent selection na EBSD measurement conditions pia haziko clear. Points hizi zimeelezwa bila kusahihisha source kimya kimya.

Makala hii ya Kiswahili imeandaliwa kwa kutegemea experimental methods, equations, tables, microstructure images, stress maps na mechanical results za uploaded study. Hakuna industrial production success, fatigue performance, toughness increase, part safety au Turkey-specific mechanical-property claim isiyokuwepo katika study iliyoongezwa.