Research articleMeasurement of the rate of transformation induced plasticity in TRIP steel by the use of Barkhausen noise emission as a function of plastic straining
Introduction
TRIP steels represent a specific group of high strength steels with improved formability developed for the car industry. The pioneer work was carried out by Zackey and Parker [1]. The authors proposed the heat treatment regime which resulted in a significant amount of retained austenite (metastable) in the matrix. As a result, TRIP steels exhibit low yield strength and delayed plastic instability (prolonged phase of homogeneous plastic straining) [1]. The TRIP mechanism prevents strain localisation via transformation of metastable austenite to martensite [2]. This transformation hardens the region in which the phase transformation takes place. TRIP steels possess unique high energy absorption [3]. For this reason, these steels are proposed for components in which high accumulation of energy during plastic deformation (high strain hardening) is expected. The final microstructure of TRIP steels after heat treatment comprises ferrite, bainitic ferrite, retained austenite and martensite [3], [4]. The austenite and ferrite phases improve the ductility of TRIP steel, whereas bainitic ferrite and martensite enhance its strength. Plastic deformation in TRIP steels is driven by internal stresses in the matrix and the strain induced transformation of austenite to martensite accompanied by stress relaxation [3]. The effectiveness of the TRIP effect is a function of many variables such as carbon enrichment of the austenite phase, the heat treatment regime, the chemical and phases composition, etc. [3], [4], [5], [6], [7], [8], [9]. El-Sherbiny et al. [5] reported about improved mechanical properties and coatability of the different TRIP steels as a result of the replacement of Si by Al and V. Zeng et al. [6] investigated the influence of Nb and Ti micro alloying on yield strength and total elongation of -TRIP C-Mn-Al-Si steel. The authors indicated that nano-sized (Nb, Ti)C precipitates improve the strength of this steel. Tan et al. [7] discussed the influence of the variable phase composition on strain partitioning and mechanical properties. A deeper insight into this field was published later [4] when strain, as well as chemical partitioning, was investigated. TRIP steels properties were examined as a function strain rate and temperature [8], [9]. Tilak Kumar et al. [9] found that elevated temperatures affect the thermal stability of austenite; thus, decreasing the yield and ultimate strength, as well as the elongation. Apart from the conventional tensile tests, the influence of stir welding [10], hydrogen embrittlement [11], and repetitive corrugation and straightening [12] on TRIP steel’s microstructure have also been investigated.
Components made of TRIP steels in a variety of applications can undergo plastic deformation of varying degrees which, in turn, results in corresponding matrix alterations expressed in many terms. Non-destructive monitoring of these parts could be beneficial for a fast and reliable assessment of the microstructural state. This information can be employed for the estimation of lifetime and/or evaluation of the components capability to absorb energy during the next loading. TRIP steels are composed of ferromagnetic phases such as ferrite, bainitic ferrite and/or martensite, as well as a certain fraction of non-ferromagnetic austenite. Strain induced phase transformation of austenite to martensite increases the volume fraction of the ferromagnetic phase [13], [14], [15]. For this reason, magnetic methods have been employed for the detection of the strain induced martensite transformation [16], [17], [18]. However, these methods have been mainly adapted for the steels whose initial microstructure was entirely composed of austenite. The main advantage of magnetic methods is driven by the marked contrast in signals (or parameters) between the paramagnetic austenite phase and the ferromagnetic martensite one.
On the other hand, studies in which magnetic Barkhausen noise (MBN) is associated with martensite/austenite partitioning are rare. Tavares et al. [19] correlated MBN with martensite/austenite partitioning in stainless steel. Vértesy et al. [20] employed different magnetic methods for non-destructive characterisation of TRIP steels exposed to variable plastic straining, including the MBN technique. The authors reported that the effective value of MBN decreases steeply, up to 7.5% strain, followed by only a moderate decrease. MBN is a product of irreversible and discontinuous domain walls (DWs) motion initiated by altering the magnetic field or/and stress [21], [22]. Domain walls (DWs) are pinned in their positions and their sudden jumps occur as soon as the magnetic field attains a critical threshold. MBN is a function of the stress state due to the specific alignment of DWs [23], [24], as well as the microstructure. DWs in motion interfere with all lattice defects such as grain boundaries [25], precipitates [25], [26], dislocation cells [27], and non-ferromagnetic phases [28] etc. whose superimposed contribution to the entire MBN is usually difficult to unwrap. On the other hand, MBN signals have been studied as a function of residual stresses [29], microstructural features [30], as well as their superimposed contribution. TRIP steels during plastic straining undergo marked microstructural transformations as well as stress alterations. For this reason, this study investigates the potential of using the MBN technique for the assessment of the microstructural state after different plastic straining under the uniaxial tensile test. The novelty of this study should be found in the deeper insight into the MBN evolution with respect to the austenite decomposition and the superimposing dislocation motion as the main mechanisms contributing to the strain hardening of TRIP steels.
Section snippets
Experimental methods
Experiments were carried out on the galvanised TRIP steel RAK 40/70+Z1000MBO of the initial thickness 0.75 mm (thickness of Zn galvanised layer varies from 6 up to 7 m). The microstructure of the investigated steel (as-received) is illustrated in Fig. 1. The microstructure of this TRIP steel (as-received) is composed of austenite (13.6%), ferrite (47.6%), bainitic ferrite (28.3%) and martensite (10.5%) [31]. Austenite fraction was obtained from XRD measurements, whereas martensite fraction
Microhardness measurements and EBSD observations
Plastic deformation of TRIP steel initiates the strain induced martensite transformation when the metastable austenite phase is decomposed, combined with superimposing dislocation slip (the corresponding increase in dislocation density). The aforementioned mechanisms contribute to the progressive growth of the matrix microhardness, as Fig. 4 illustrates. This figure also depicts that the growth of HV1 is steeper for the lower plastic strains and becomes moderate beyond %. Finally, a quite
Discussion
Strain induced martensite transformation can be found in TRIP as well as some austenitic steels. However, the evolution of MBN in these steels is markedly different. MBN originating from austenitic steels is zero and MBN usually shows a marked growth as a result of the increasing fraction of strain induced transformation of austenite to martensite [16], [17]. On the other hand, austenite is only a minor phase in TRIP steel and the MBN evolution is driven by the contribution of bainitic ferrite
Conclusions
The findings of this study can be summarised as follows:
- -
Decomposition of metastable austenite in RAK 40/70 TRIP steel is accelerated at lower strains,
- -
MBN in the RD shows a steep decrease, especially in the region of accelerated austenite decomposition,
- -
A more marked extent of increasing dislocation density in the ferrite and bainitic ferrite grains interior can be found at higher strains when MBN in the RD saturates,
- -
Moderate growth of PP during accelerated austenite decomposition is followed by
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
J.Č. thanks to the project CZ.02.1.01/0.0/0.0/16_019/0000778 ”Center for advanced applied science” within the Operational Program Research, Development and Education supervised by the Ministry of Education, Youth and Sports of the Czech Republic. This publication was also realisedwith support of Operational Program Integrated Infrastructure 2014–2020 of the project : Innovative Solutions for Propulsion, Power and Safety Components of Transport Vehicles, code ITMS 313011V334, co-financed by the
References (51)
- et al.
Numerical simulation on magnetic–mechanical behaviors of 304 austenite stainless steel
Meas
(2020) - et al.
Joint investigation of strain partitioning and chemical partitioning in ferrite-containing TRIP-assisted steels
Acta Mater
(2020) - et al.
Replacement of silicon by aluminium with the aid of vanadium for galvanized TRIP steel
J Mater Res Technol
(2020) - et al.
Microstructure and mechanical properties of Nb and Ti microalloyed lightweight -TRIP steel
Mat Char
(2020) - et al.
Effect of matrix structures on TRIP effect and mechanical properties of low-C low-Si Al-added hot-rolled TRIP steels
Mater Sci Eng A
(2020) - et al.
Abnormal TRIP effect on the work hardening behaviour of a quenching and partitioning steel at high strain rate
Acta Mater
(2020) - et al.
Influence of strain rate and strain at temperature on TRIP effect in metastable austenitic stainless steel
Mater Sci Eng A
(2020) - et al.
Achieving extraordinary strength and ductility in TRIP steels through stabilization of austenite up to 99.8% by friction stir welding
Mater Sci Eng A
(2020) - et al.
EBSD characterization of hydrogen induced blisters and internal cracks in TRIP-assisted steel
Mat Char
(2020) - et al.
Microstructural development and its effect on tensile properties of a high Ni TRIP steel produced by repetitive corrugation and straightening via rolling (RCSR)
J Mater Res Technol
(2020)
Characterization of strain-induced martensitic transformation in a metastable stainless steel
Mater Des
Effect of strain induced martensite reversal on the degree of sensitization of metastable austenitic stainless steel
Proc Struct Integr
Characterization of strain-induced martensitic transformation in A301 stainless steel by Barkhausen noise measurement
Mater Des
Investigation of shot-peened austenitic stainless steel 304L by means of magnetic Barkhausen noise
Mater Sci Eng A
Temper embrittlement of super martensitic stainless steel and non-destructive inspection by magnetic Barkhausen noise
Eng Fail Anal
Nondestructive magnetic characterization of TRIP steels
NDTE Int
Quantitative evaluation of residual stress and surface hardness in deep drawn parts based on magnetic Barkhausen noise technology
Meas
A novel system for non-destructive evaluation of surface stress in pipelines using rotational continuous magnetic Barkhausen noise
Meas
Barkhausen Noise as a microstructure characterization tool
Phys B
An investigation into the applicability of Barkhausen noise technique in evaluation of machining properties of high carbon steel parts with different degrees of spheroidization
J Magn Magn Mater
Non-destructive monitoring of corrosion extent in steel rope wires via Barkhausen noise emission
J Magn Magn Mater
Non-destructive hardness prediction for 18CrNiMo7-6 steel based on feature selection and fusion of Magnetic Barkhausen Noise
NDTE Int
Extraction of Barkhausen noise from the measured raw signal in high-frequency regimes
Meas
Detection of a milling-induced surface damage by the magnetic Barkhausen noise
J Magn Magn Mater
Barkhausen noise emission in tool steel X210Cr12 after semi-solid processing
Mater Char
Cited by (9)
Measurement of bearing capacity of steel road barrier flange via Barkhausen noise emission
2024, Engineering Failure AnalysisMagnetic non-destructive monitoring of a ship's propeller blade after long-term operation
2024, Ocean EngineeringBarkhausen noise emission of AISI 304 stainless steel originating from strain induced martensite by shot peening
2022, Journal of Materials Research and TechnologyCitation Excerpt :It seems that this figure provides nearly the same information as that introduced by Fig. 12a. However, the ratio R90/R180 in Fig. 17b illustrates the local minimum after 4 cycles, and this evolution is inversely proportional to the near-surface microhardness, see also Fig. 5b. On the one hand, the prolonged activity of the 90° DWs can be linked with a remarkable magnetic anisotropy and the preferential DW alignment in the easy axis of magnetisation. For this reason, R90/R180 is more pronounced for the TD than for the RD, see Fig. 17b. On the other hand, a richer R90 and a corresponding higher R90/R180 ratio can also be detected when the higher density of lattice imperfections such as precipitates, grain boundaries, non-ferromagnetic phases, or microcracks are developed, c.f [17,37]. Therefore, the increase in R90/R180 after 6 and 8 SP cycles in the RD and TD is mainly due to surface microcracking, whereas the higher R90/R180 after 2 SP cycles is mainly due to the lower martensite fraction and its fragmentation in austenite.
Mechanical and magnetic properties of TRIP690 steel strengthened by strain-induced martensite
2022, Journal of Magnetism and Magnetic MaterialsCitation Excerpt :The results show that the relationship between austenite volume fraction and magnetic properties is in good agreement [29,30] and that the transformation process of austenite volume fraction in TRIP steels can be characterized by magnetic testing methods. The magnetic Barkhausen noise signal can be used to explain the magnetic anisotropy behavior of TRIP steels after martensitisation [31]. Despite a large number of studies and reports dealing with the identification and quantitative analysis of the microstructure to the magnetic phenomenology, the contribution of metallurgical transformations such as the refinement of ferrite, the transformation of retained austenite, and the increment of martensite to the mechanical properties and the magnetic properties of TRIP steels needs to be analyzed more precisely.
Formation of Effective Non-ferromagnetic Barrier in Fe/MgO Soft Magnetic Composite
2024, ACS Applied Electronic Materials