scholarly journals Microstructural Characteristics and Strengthening Mechanisms of Ferritic–Martensitic Dual-Phase Steels: A Review

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 101
Author(s):  
Farzad Badkoobeh ◽  
Hossein Mostaan ◽  
Mahdi Rafiei ◽  
Hamid Reza Bakhsheshi-Rad ◽  
Filippo Berto
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
High Strength Steels ◽  
High Strength ◽  
Extensive Study ◽  
Review Article ◽  
Dual Phase ◽  
Strengthening Mechanisms ◽  
Microstructural Characteristics ◽  
Dp Steels

Ferritic–martensitic dual-phase (DP) steels are prominent and advanced high-strength steels (AHSS) broadly employed in automotive industries. Hence, extensive study is conducted regarding the relationship between the microstructure and mechanical properties of DP steels due to the high importance of DP steels in these industries. In this respect, this paper was aimed at reviewing the microstructural characteristics and strengthening mechanisms of DP steels. This review article represents that the main microstructural characteristics of DP steels include the ferrite grain size (FGS), martensite volume fraction (MVF), and martensite morphology (MM), which play a key role in the strengthening mechanisms and mechanical properties. In other words, these can act as strengthening factors, which were separately considered in this paper. Thus, the properties of DP steels are intensely governed by focusing on these characteristics (i.e., FGS, MVF, and MM). This review article addressed the improvement techniques of strengthening mechanisms and the effects of hardening factors on mechanical properties. The relevant techniques were also made up of several processing routes, e.g., thermal cycling, cold rolling, hot rolling, etc., that could make a great strength–ductility balance. Lastly, this review paper could provide substantial assistance to researchers and automotive engineers for DP steel manufacturing with excellent properties. Hence, researchers and automotive engineers are also able to design automobiles using DP steels that possess the lowest fuel consumption and prevent accidents that result from premature mechanical failures.

Change of Mechanical Properties of High Strength Line Pipe by Thermal Coating Treatment

2005 ◽  
Author(s):  
Yasuhiro Shinohara ◽  
Takuya Hara ◽  
Eiji Tsuru ◽  
Hitoshi Asahi ◽  
Yoshio Terada ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Uniform Elongation ◽  
High Strength ◽  
Secondary Phase ◽  
Longitudinal Direction ◽  
Dual Phase ◽  
Line Pipe ◽  
Thermal Coating ◽  
Production Conditions

In strain-based design, the overmatch condition in the girth weld portion primarily must be maintained. The pipes may also be required to have a low yield to tensile (Y/T) ratio and a high uniform elongation (U.EL) in the longitudinal direction to achieve a high compressive buckling strain. However, change in the mechanical properties by heating during coating treatment has not been paid attention so much. Furthermore, how much the mechanical properties change is affected by production conditions is unclear. This study aims to clarify firstly the relation between the mechanical properties (Y/T ratio, U.EL etc.) and the microstructure and secondly the change in mechanical properties by thermal coating treatment. The Y/T ratio and U.EL are affected by the volume fraction of ferrite and the secondary phase, which are changed by thermomechanical control processing (TMCP) conditions. For example, use of dual phase microstructure is very effective for decreasing the Y/T ratio and increasing the U.EL as the pipe. On the other hand, yield strength (YS) rises and the U.EL does not change after coating. The increase in the YS after coating is influenced by the microstructure and TMCP conditions. Resultantly, dependence of the Y/T ratio on the microstructure and TMCP conditions is reduced for line pipes after thermal coating treatment.

The Draw-Bend Fracture Test and Its Application to Dual-Phase and Transformation Induced Plasticity Steels

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Ji Hyun Sung ◽  
Ji Hoon Kim ◽  
R. H. Wagoner
Keyword(s):  
Shear Fracture ◽  
High Strength Steels ◽  
High Strength ◽  
High Energy ◽  
Tensile Failure ◽  
Dual Phase ◽  
Transformation Induced Plasticity ◽  
Advanced High Strength Steels ◽  
Energy Product ◽  
Dp Steels

Unpredicted sheet forming failures of dual-phase (DP) steels can occur in regions of high curvature and with little apparent necking. Such failures are often referred to as “shear fractures”. In order to reproduce such fractures in a laboratory setting, and to understand their origin and the inability to predict them, a novel draw-bend formability (DBF) test was devised using dual displacement rate control. DP steels from several suppliers, with tensile strengths ranging from 590 to 980 MPa, were tested over a range of rates and bend ratios (R/t) along with a TRIP (transformation induced plasticity) steel for comparison. The new test reliably reproduced three kinds of failures identified as types 1, 2, and 3, corresponding to tensile failure, transitional failure, and shear fracture, respectively. The type of failure depends on R/t and strain rate, and presumably on the initial specimen width, which was constant in this study. Two critical factors influencing the lack of accurate failure prediction were identified. The dominant one is deformation-induced heating, which is particularly significant for advanced high strength steels because of their high energy product. Temperature rises of up to 100 deg. C were observed. This factor reduces formability at higher strain rates, and promotes a transition from types 1 to 3. The second factor is related to microstructural features. It was significant in only one material in one test direction (of 11 tested) and only for this case was the local fracture strain different from that in a tensile failure. Alternate measures for assessing draw-bend formability were introduced and compared. They can be used to rank the formability of competing materials and to detect processing problems that lead to unsuitable microstructures.

scholarly journals Study of Diffusible Behavior of Hydrogen in First Generation Advanced High Strength Steels

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 782
Author(s):  
Dwaipayan Mallick ◽  
Nicolas Mary ◽  
V. S. Raja ◽  
Bernard Normand
Keyword(s):  
Diffusion Coefficients ◽  
First Generation ◽  
High Strength Steels ◽  
High Strength ◽  
Specimen Thickness ◽  
Dual Phase ◽  
Complex Phase ◽  
Advanced High Strength Steels ◽  
Permeation Studies ◽  
Dp Steels

This study deals with microstructural influence on the H permeation behavior of Dual-Phase (DP) and Complex Phase (CP) steels using electrochemical permeation studies. The H diffusion coefficients in DP steels (DP800: 1.65 × 10−10 m2·s−1, DP1000: 1.58 × 10−10 m2·s−1) are half of that found in CP steels (3.07 × 10−10 m2·s−1).The banded microstructure along the specimen thickness and higher C content of the DP led to high H diffusivity of DP steels. The lower total H concentration along with a higher fraction of H was present in the stronger traps in CP steels suggest a better HE resistance of this steel. The H distribution in the specimens was non-uniform, with a higher H concentration speculated near the charging surface.

scholarly journals The Effect of Mn and Si on the Properties of Advanced High Strength Steels Processed by Quenching and Partitioning

2010 ◽  
Vol 654-656 ◽  
pp. 94-97 ◽  
Author(s):  
Bohuslav Mašek ◽  
Hana Jirková ◽  
Daniela Hauserova ◽  
Ludmila Kučerová ◽  
Danuše Klauberová
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
Volume Fraction ◽  
High Strength Steels ◽  
High Strength ◽  
Microstructural Development ◽  
X Ray Diffraction ◽  
Quenching And Partitioning ◽  
Advanced High Strength Steels ◽  
High Ultimate Strength

The concepts new types of materials are, for economic reasons, focused mainly on low alloyed steels with a good combination of strength and ductility. Suitable heat and thermo-mechanical treatments play an important role for the utilization of these materials. Different alloying strategies are used to influence phase transformations. The quenching and partitioning process (Q-P Process) is one of the heat treatment methods which can result in a high ultimate strength as well as a good ductility. However, these good properties can be obtained only if a sufficient amount of retained austenite is stabilized. The influence of different contents of manganese, silicon and chromium on microstructural development and mechanical properties were experimentally tested. Alloying elements were used to stabilize the retained austenite in the final microstructure and also to strengthen the solid solution. Ultimate strengths of over 2000MPa with ductility over 10% were reached after the optimization of the Q-P Process. The microstructures were analyzed using several microscopic methods; mechanical properties were determined by a tensile test and the volume fraction of the retained austenite was established by X-ray diffraction phase analysis.

Multiscale Material Modeling and Simulation of the Mechanical Behavior of Dual Phase Steels Under Different Strain Rates: Parametric Study and Optimization

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Tarek M. Belgasam ◽  
Hussein M. Zbib
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Volume Fraction ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Dual Phase ◽  
Strain Rates ◽  
Microstructure Parameters ◽  
Dp Steels

Recent studies on developing dual phase (DP) steels showed that the combination of strength/ductility could be significantly improved when changing the volume fraction and grain size of phases in the microstructure depending on microstructure properties. Consequently, DP steel manufacturers are interested in predicting microstructure properties as well as optimizing microstructure design at different strain rate conditions. In this work, a microstructure-based approach using a multiscale material and structure model was developed. The approach examined the mechanical behavior of DP steels using virtual tensile tests with a full micro-macro multiscale material model to identify specific mechanical properties. Microstructures with varied ferrite grain sizes, martensite volume fractions, and carbon content in DP steels were also studied. The influence of these microscopic parameters at different strain rates on the mechanical properties of DP steels was examined numerically using a full micro-macro multiscale finite element method. An elasto-viscoplastic constitutive model and a response surface methodology (RSM) were used to determine the optimum microstructure parameters for a required combination of strength/ductility at different strain rates. The results from the numerical simulations were compared with experimental results found in the literature. The developed methodology proved to be a powerful tool for studying the effect and interaction of key strain rate sensitivity and microstructure parameters on mechanical behavior and thus can be used to identify optimum microstructural conditions at different strain rates.

Resistance Spot Welding (RSW) Process Optimization for Uncoated 2.0mm Dual Phase 780 to 2.0 mm Uncoated 2.0 mm Dual Phase 780 (DP780) Steel for Automotive Applications

2008 ◽  
Author(s):  
Ramakrishna Koganti ◽  
Sergio Angotti ◽  
Arnon Wexler ◽  
Donald F. Maatz
Keyword(s):  
Mechanical Properties ◽  
Cross Section ◽  
Hold Time ◽  
Tensile Load ◽  
High Strength Steels ◽  
High Strength ◽  
Weld Nugget ◽  
Dual Phase ◽  
Section Data ◽  
Cross Tension

There has been a substantial increase in the use of advanced high strength steel in automotive structures in the last few years. The usage of these materials is projected to grow significantly in the next 5–10 years with new safety and fuel economy regulations. Advanced High Strength Steels (AHSS) are getting popular with superior mechanical properties and weight advantages compared to mild steel materials. These new materials have significant manufacturing challenges, particularly for welding and stamping. Proper understanding of the weldability of these materials is critical for successful application in future vehicle programs. Due to high strength nature of AHSS materials, higher weld forces and longer weld times are needed to weld AHSS materials. This work is in support of lightweight structures development and during the weld development phase various gages of coated and uncoated AHSS materials (DP780, DP980, TRIP780, Boron, Algoma 700B) were investigated. Both 2T and 3T stack-up conditions were investigated. Also, some combination of AHSS materials with High Strength Low Alloy (HSLA) and Bake Hardenable 210 (BH210) electro galvanized (EG) steels were also investigated. In this paper, weld lobe development for 2.0 mm DP780 bare to 2.0 mm DP780 bare 2T stack-up combination is discussed. Weld lobes were developed with Mid Frequency Direct Current (MFDC) equipment, ISO type B-20 tip, constant weld force of 6.36 kN (1430 lbf), hold time of 5 cycles and the weld times were varied 21, 24 and 27 cycles. Based on the tensile, cross-tension and nugget data, there were no correlations were observed between tensile load and button size and also between cross-tension and button size. Weld cross section data indicated heat affected zone (HAZ) at the weld nugget area and hardness drop of 17% was observed at the HAZ area. Irrespective of weld cycles, similar HAZ was observed close to the weld nugget. The weld lobes, mechanical properties (tensile shear and cross tension), cross-section examination, and microhardness of 2.0 mm DP780 bare to 2.0 mm DP780 bare weld 2T stack-up results are discussed.

scholarly journals Effect of Heat Input and Undermatched Filler Wire on the Microstructure and Mechanical Properties of Dissimilar S700MC/S960QC High-Strength Steels

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 883 ◽  
Author(s):  
Francois Njock Bayock ◽  
Paul Kah ◽  
Belinga Mvola ◽  
Pavel Layus
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Heat Affected Zone ◽  
Heat Input ◽  
Volume Fraction ◽  
Base Material ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Microstructure And Mechanical Properties

The effect of heat input on the microstructure and mechanical properties of dissimilar S700MC/S960QC high-strength steels (HSS) using undermatched filler material was evaluated. Experiments were performed using the gas metal arc welding process to weld three samples, which had three different heat input values (i.e., 15 kJ/cm, 7 kJ/cm, and 10 kJ/cm). The cooling continuous temperature (CCT) diagrams, macro-hardness values, microstructure formations, alloy element compositions, and tensile test analyses were performed with the aim of providing valuable information for improving the strength of the heat-affected zone (HAZ) of both materials. Micro-hardness measurement was conducted using the Vickers hardness test and microstructural evaluation by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The mechanical properties were characterized by tensile testing. Dissimilar welded samples (S700MC/S960QC) with a cooling rate of 10 °C/s (15 kJ/cm) showed a lower than average hardness (210 HV5) in the HAZ of S700MC than S960QC. This hardness was 18% lower compared to the value of the base material (BM). The best microstructure formation was obtained using a heat input of 10 kJ/cm, which led to the formation of bainite (B, 60% volume fraction), ferrite (F, 25% volume fraction), and retained austenite (RA, 10%) in the final microstructure of S700MC, and B (55%), martensite (M, 45%), and RA (10%), which developed at the end of the transformation of S960QC. The results showed the presence of 1.3 Ni, 0.4 Mo, and 1.6 Mn in the fine-grain heat-affected zone of S700MC. The formation of a higher carbide content at a lower cooling rate reduced both the hardness and strength.

Effect of Microstructure on Mechanical Properties and Abrasive Wear Behavior of Low Carbon Dual-Phase Steels

2014 ◽  
Author(s):  
Mehmet Çağrı Tüzemen ◽  
Elmas Salamci
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Wear Behavior ◽  
Steel Specimen ◽  
Total Elongation ◽  
Dry Sliding Wear ◽  
Dual Phase ◽  
Low Carbon ◽  
Wear Properties ◽  
Dp Steels

The mechanical properties and wear behavior of Dual Phase (DP) steels have been investigated and compared with those observed in normalized (N) steel that has the same chemical composition. The DP steels having different content and morphology of martensite were produced by varying intercritical annealing temperature and initial microstructures. Mechanical properties of four different DP steels and N steel have been investigated by carrying out tensile and macrohardness tests. Dry sliding wear tests have been conducted on four different the DP steels and the N steel using pin-on-plate to investigate their wear characteristics. It has been found that the yield and tensile strengths and macrohardness increase with increasing martensite content and decreasing martensite size. The yield and tensile strengths and macrohardness of the N steel were significantly lower than the DP steels whereas percentage of total elongation was higher. Wear properties are improved by increasing martensite volume fraction and size in the DP steels. The N steel specimen showed the highest wear rate.

Topological Analysis of Martensite Morphology in Dual-Phase Steels

2011 ◽  
Vol 409 ◽  
pp. 725-729 ◽  
Author(s):  
Naoko Sato ◽  
Mayumi Ojima ◽  
Satoshi Morooka ◽  
Yo Tomota ◽  
Yoshitaka Adachi
Keyword(s):  
Mechanical Properties ◽  
Work Hardening ◽  
Annealing Temperature ◽  
Volume Fraction ◽  
Intercritical Annealing ◽  
Topological Analysis ◽  
Three Dimensional ◽  
Dual Phase ◽  
Hardening Behavior ◽  
Dp Steels

Martensite morphology such as connectivity or dispersivity in ferrite (F)/martensite (M) dual-phase (DP) steels was investigated from topological viewpoint to reveal the effect of the martensite morphology on the mechanical properties. Topological analysis permits evaluation of the microstructural connectivity and dispersivity by measuring the number of handles, independent bodies and genus, etc. The topological analysis was performed on three-dimensional (3D) reconstructed images of the microstructure with different connectivity, dispersivity, volume fraction and hardness of martensite in DP steels that were prepared by changing the intercritical annealing temperature. The connectivity and the volume fraction of martensite increased while the dispersivity and hardness of it decreased with increasing annealing temperature. The effect of connectivity and dispersivity as well as volume fraction and hardness, in particular, on work hardening behavior was individually evaluated at a given strain.

Effects of cooling rate on the mechanical properties of dual phase treated vanadium steels

1983 ◽  
Vol 41 ◽  
pp. 220-221
Author(s):  
L.J. Chen ◽  
H.C. Cheng ◽  
J.R. Gong ◽  
J.G. Yang
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Automobile Industry ◽  
High Strength ◽  
Weight Percent ◽  
Low Alloy Steels ◽  
Dual Phase ◽  
Resource Requirement ◽  
Alloy Steels ◽  
Potential Weight

For fuel savings as well as energy and resource requirement, high strength low alloy steels (HSLA) are of particular interest to automobile industry because of the potential weight reduction which can be achieved by using thinner section of these steels to carry the same load and thus to improve the fuel mileage. Dual phase treatment has been utilized to obtain superior strength and ductility combinations compared to the HSLA of identical composition. Recently, cooling rate following heat treatment was found to be important to the tensile properties of the dual phase steels. In this paper, we report the results of the investigation of cooling rate on the microstructures and mechanical properties of several vanadium HSLA steels.The steels with composition (in weight percent) listed below were supplied by China Steel Corporation: 1. low V steel (0.11C, 0.65Si, 1.63Mn, 0.015P, 0.008S, 0.084Aℓ, 0.004V), 2. 0.059V steel (0.13C, 0.62S1, 1.59Mn, 0.012P, 0.008S, 0.065Aℓ, 0.059V), 3. 0.10V steel (0.11C, 0.58Si, 1.58Mn, 0.017P, 0.008S, 0.068Aℓ, 0.10V).

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