Diffraction Analysis at the Meso and Micro Scale During the Mechanically Induced Martensite Phase Transformation

ICOMAT ◽  
2013 ◽  
pp. 255-262
Author(s):  
B. Malard ◽  
G. Geandier ◽  
J. Wright ◽  
T. Buslaps ◽  
S. Berveiller ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Diffraction Analysis ◽  
Martensite Phase ◽  
Micro Scale

Influence of material parameters on 2D-martensitic transformation based on the phase-field finite-element method

2019 ◽  
Vol 116 (6) ◽  
pp. 614
Author(s):  
Li Chang ◽  
Gao Jingxiang ◽  
Zhang Dacheng ◽  
Chen Zhengwei ◽  
Han Xing
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Phase Transformation ◽  
Martensitic Transformation ◽  
Phase Field ◽  
Martensite Transformation ◽  
Transformation Process ◽  
Martensite Phase ◽  
Phase Field Method ◽  
Element Method

Obtaining an accurate microscopic representation of the martensitic transformation process is key to realizing the best performance of materials and is of great significance in the field of material design. Due to the martensite phase transformation is rapidly, the current experimental is hard to capture all the information in the Martensite phase transformation process. Combining the phase-field method with the finite-element method, a model of martensitic transformation from a metastable state to a steady state is established. The law of a single martensite nucleus during martensitic transformation is accurately described. By changing the key materials that affect martensite transformation and the phase-field parameters, the effects of the parameters on the single martensitic nucleation process are obtained. This study provides an important theoretical basis for effectively revealing the essence of martensite transformation and can determine effective ways to influence martensite transformation, obtain the optimal parameters and improve the mechanical properties of such materials.

scholarly journals The Effect of Drawing Deformation Rate Induced Inhomogeneous Local Distortion on Phase Transformation of 304H Stainless Wire

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1304
Author(s):  
Qinhua Xu ◽  
Zhixian Peng ◽  
Jianxin Zhu ◽  
Mingyang Li ◽  
Yong Zong ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Phase Transformation ◽  
Heat Generation ◽  
Martensite Transformation ◽  
Local Strain ◽  
Cold Drawing ◽  
Element Distribution ◽  
Martensite Phase ◽  
Single Strain ◽  
Area Reduction

The micro/macro magnetic properties, local element distribution, martensite transformation, and mechanical properties of 304H stainless wires are determined for two cold drawing chains. Finite element simulations are used to analyse the local strain and heat generation. The results show that there is obvious inhomogeneity in the magnetic properties, strain/stress relationship, and strain-induced heat within the drawn wires. Comparing wires with the same total strain, a larger area reduction of previous drawing processes contributes to a higher volume of the martensite phase, while a smaller area reduction of the first process results in an inhibited phase transformation. A higher single strain in the first drawing process leads to additional heat generation at the subsurface of the wire, which would eventually retard the martensite transformation. The inhomogeneous deformation-induced differences in the grain size affect the stability of austenite and transform the final martensite.

Study on Microstructure of Quenched Martensite in W6Mo5Cr4V2 Steel

2011 ◽  
Vol 295-297 ◽  
pp. 175-178
Author(s):  
Yun Ping Ji ◽  
Zong Chang Liu ◽  
Hui Ping Ren
Keyword(s):  
Phase Transformation ◽  
Small Area ◽  
Martensite Phase ◽  
Stacking Fault ◽  
Plate Martensite ◽  
Twin Crystal ◽  
Transmission Electron ◽  
Starting Point ◽  
Austenite Grains ◽  
The Difference

The microstructure and the formation mechanism of martensite in W6Mo5Cr4V2 steel was studied by metallographic microscope and JEM-2100 transmission electron microscope after the samples were austenized between the temperatures of Ac1~Accm and then quenched. The results show that When heating W6Mo5Cr4V2 steel samples between the temperatures of Ac1~Accm and then quenching, the cryptocrystalline martensite will be obtained. The cryptocrystalline martensite is plate martensite actually. It is considered that the formation cause of the cryptocrystal martensite is extremely inhomogeneous chemical composition in the austenite grains and the difference of martensite starting point (Ms point) of every small area in austenite grains. Besides the high-density dislocation and the fine twin crystal, the substructure of the cryptocrystalline martensite includes the superfine stacking fault. The stacking fault is caused by the stacking misarrangement during the crystal lattice reconstruction of martensite phase transformation. The midrib exists in the cryptocrystal martensite of W6Mo5Cr4V2 steel, which is composed of the fine twin crystal plates. The shear mechanism can not account for the formation of the martensite midrib.

The Study of Ultrasonic Dynamic Elastic Modulus of TiNiFe Shape Memory Alloy in Heating Process

2009 ◽  
Vol 79-82 ◽  
pp. 1699-1702
Author(s):  
Xiao Peng Gao ◽  
Fu Shun Liu
Keyword(s):  
Phase Transformation ◽  
Elastic Modulus ◽  
Test Temperature ◽  
Martensite Transformation ◽  
Martensite Phase ◽  
Austenite Phase ◽  
Dynamic Elastic Modulus ◽  
Heating Process ◽  
Static Tensile ◽  
Tensile Elastic Modulus

The phase transformation characteristics, the dynamic elastic modulus and the static tensile elastic modulus of Ti50Ni47.5Fe2.5 alloy were investigated. It is found that, the two mutations in the dynamic elastic modulus is caused by reverse martensite phase transformation and austenite phase transformation respectively; Static tensile test can not reflect the intrinsic elastic modulus when the test temperature is close to martensite transformation temperature(Ms). The static elastic modulus and the dynamic elastic modulus have the same trend when the test temperature is enough higher than Ms.

Austenite-Martensite Phase Transformation of Biomedical Ni50.8Ti49.2 Alloy by Ball Burnishing

2013 ◽  
Author(s):  
C. H. Fu ◽  
Y. B. Guo ◽  
X. T. Wei
Keyword(s):  
Phase Transformation ◽  
Martensite Phase ◽  
Ball Burnishing ◽  
Transformation Mechanism ◽  
Promising Technique ◽  
Workpiece Surface ◽  
Aerospace Applications ◽  
Modify Surface ◽  
Surface Phase Transformation ◽  
Shed Light

Nitinol alloys have received considerable attentions in biomedical and aerospace applications. They can exhibit both austenite and martensite phases at room temperature. Austenite can transform to martensite by applied stress or temperature. Ball burnishing is a very promising technique to modify surface integrity via plastic deformation on the workpiece surface. Phase transformation of Nitinol by burnishing may occur at certain load, which results in the mechanical property change on the workpiece. A burnishing experiment has been conducted in this research at different burnishing loads. The burnishing tracks are characterized and microstructures in the subsurface are studied. A corresponding simulation is also performed to shed light on phase transformation mechanism of Nitinol in burnishing.

Finite element analysis of the phase transformation effect in residual stresses generated by quenching in notched steel cylinders

2005 ◽  
Vol 40 (2) ◽  
pp. 151-160 ◽  
Author(s):  
E P Silva ◽  
P M C L Pacheco ◽  
M. A Savi
Keyword(s):  
Finite Element ◽  
Phase Transformation ◽  
Residual Stresses ◽  
Induction Hardening ◽  
Martensite Phase ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Thermomechanical Behaviour ◽  
Quenching Process

The determination of residual stresses is an important task in the analysis of the quenching process. Nevertheless, because of the complexity of the phenomenon, many simplifications are usually adopted in the prediction of these stresses for engineering purposes. One of these simplifications is the effect of phase transformation. Many studies analyse residual stresses generated by the quenching process considering a thermoelastoplastic approach, neglecting phase transformation. The present study analyses the effect of austenite-martensite phase transformation during quenching in the determination of residual stresses, comparing two different models: complete (thermoelastoplastic model with austenite-martensite phase transformation) and without phase transformation (thermoelastoplastic model without phase transformation). The finite element method is employed for spatial discretization together with a constitutive model that represents the thermomechanical behaviour of the quenching process. Progressive induction hardening of steel cylinders with semicircular notches is of concern. Numerical simulations show situations where great discrepancies are introduced in the predicted residual stresses if phase transformation is neglected.

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