scholarly journals Metallurgical Effects of Niobium in Dual Phase Steel

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 504 ◽  
Author(s):  
Hardy Mohrbacher ◽  
Jer-Ren Yang ◽  
Yu-Wen Chen ◽  
Johannes Rehrl ◽  
Thomas Hebesberger
Keyword(s):  
Dual Phase Steel ◽  
Dual Phase ◽  
Steel Matrix ◽  
High Ductility ◽  
Dp Steel ◽  
Industrial Processing ◽  
Automotive Body ◽  
Niobium Microalloying ◽  
Body Design ◽  
Kinetics Of

Dual phase (DP) steels are widely applied in today’s automotive body design. The favorable combination of strength and ductility in such steels is in first place related to the share of ferrite and martensite. The pronounced work hardening behavior prevents localized thinning and allows excellent stretch forming. Niobium microalloying was originally introduced to dual phase steel for improving bendability by refining the microstructure. More recently developed “high ductility” (HD) DP steel variants provide increased drawability aided by a small share of austenite retained in the microstructure. In this variant niobium microalloying produces grain refinement and produces a dispersion of nanometer-sized carbide precipitates in the steel matrix which additionally contributes to strength. This study investigates the microstructural evolution and progress of niobium precipitation during industrial processing of high-ductility DP 980. The observations are interpreted considering the solubility and precipitation kinetics of niobium. The influences of niobium on microstructural characteristics and its contributions to strength and formability are discussed.

scholarly journals Effect of Martensite Morphologies on Corrosion in 5% H2SO4 Solution of Borided X70 Dual Phase Steel

2021 ◽  
Vol 45 (1) ◽  
pp. 69-74
Author(s):  
Tassi Hocine ◽  
Zidelmel Sami ◽  
Allaoui Omar
Keyword(s):  
Corrosion Resistance ◽  
Dual Phase Steel ◽  
Annealing Temperature ◽  
Intercritical Annealing ◽  
Ferrite Matrix ◽  
Dual Phase ◽  
H2so4 Solution ◽  
Dp Steel ◽  
Direct Quenching ◽  
Step Quenching

In the present investigation, some electrochemical properties of dual phase X70 steels with different martensite morphologies which have undergone boriding were studied. To obtain a variety of martensite morphologies, Direct Quenching (DQ), Intermediate Quenching (IQ) and Step Quenching (SQ) heat treatments were applied at an intercritical annealing temperature (IAT) of 760℃. The treatment (DQ) allowed the formation of fine martensite evenly distributed in the ferrite matrix. (IQ) treatment showed the formation of martensite along the ferrite / ferrite grain boundaries. In contrast, treatment (SQ) induced the formation of a banded morphology of martensite and ferrite. The realization of borides on X70 (DP) steel was carried out in a powder mixture containing 5% of B4C as source of boron, 5% of NaBF4 as activator and 90% of SiC as diluent at 950℃ for a period of time from 4 h. The corrosion behavior of X70 (DP) steel has been explored by the Tafel extrapolation method in a 5 wt. % H2SO4 solution. The corrosion resistance of steel which has undergone boriding (BDP) is higher than that of steel which has not undergone it (DP).

Deformation Behaviour of Martensite in a Low-Carbon Dual-Phase Steel

2006 ◽  
Vol 15-17 ◽  
pp. 774-779 ◽  
Author(s):  
M. Mazinani ◽  
Warren J. Poole
Keyword(s):  
Dual Phase Steel ◽  
Volume Fraction ◽  
Deformation Behaviour ◽  
Dual Phase ◽  
Low Carbon ◽  
Heating Rates ◽  
Dp Steel ◽  
Martensite Content ◽  
High Heating ◽  
Different Temperatures

The deformation behaviour of martensite and its effect on tensile properties of a lowcarbon dual-phase (DP) steel were investigated. DP steel samples with different martensite contents and morphologies were produced after intercritical annealing at different temperatures using low and high heating rates. Two distinct martensite morphologies were obtained for low and high heating rates. The investigated steel showed the unusual results that the true fracture stress and strain were found to increase with the martensite volume fraction. The plastic deformation of martensite was considered to be responsible for these results. Experimentally, it was observed that the martensite in DP steels with greater than 25-30% martensite can deform plastically during tensile straining. Finally, the effect of tempering on the martensite plasticity was also evaluated. It was found that the tempering process and an increase in the martensite content have a similar effect on promoting martensite plasticity.

Thermo-Mechanical Simulation of Ultra-High Strength Ferrite-Bainite Dual Phase Steel

2012 ◽  
Vol 184-185 ◽  
pp. 1367-1370
Author(s):  
Wei Lv ◽  
Di Wu ◽  
Zhuang Li
Keyword(s):  
Cooling Rate ◽  
Dual Phase Steel ◽  
High Strength ◽  
Solute Drag ◽  
Dual Phase ◽  
Drag Effect ◽  
Dp Steel ◽  
Mechanical Simulation ◽  
Austenite Grain ◽  
Fast Cooling

In the present paper, thermo-mechanical simulation of ultra-high strength ferrite-bainite dual phase (DP) steel was performed using a thermomechanical simulator. Continuous cooling transformation (CCT) diagram was constructed for DP steel. The effects of composition and cooling rate on the kinetics and products of phase transformation and the form of the CCT diagram were investigated. The results have shown that the α→γ transformation in DP steel was found to be more sluggish due to the addition of alloying elements. The segregation of manganese and niobium at austenite grain boundaries is expected to cause a solute drag effect, thereby reducing the rate of γ→α transformation in DP steel. The pearlite transformation region disappeared for cooling rates from 0.1 to 20°C/s. The microstructure comprises of bainite and martenite was obtained at fast cooling rate. The present steel is expected to have a higher hardenability.

scholarly journals Microstructure and Mechanical Properties of Dual-Phase Steel/ Mikrostruktura I Własności Mechaniczne Stali Dwufazowej

2014 ◽  
Vol 59 (4) ◽  
pp. 1257-1261
Author(s):  
K. Miernik ◽  
S. Pytel
Keyword(s):  
Mechanical Properties ◽  
Dual Phase Steel ◽  
High Strength ◽  
Phase Region ◽  
Dual Phase ◽  
Two Phase ◽  
Dp Steel ◽  
Direct Quenching ◽  
Microstructure And Mechanical Properties ◽  
Tempering Treatment

Abstract The paper presents results of microstructure and mechanical properties of the dual phase (DP) steel plate with 12 mm thickness produced by intercritical annealing at a two-phase region of ferrite and austenite (α + γ) and direct quenching in water. In addition the tempering treatment at temperature of 650°C was applied to investigate effect of martensite softening on mechanical properties of the tested steel. The parameters of heat treatment were designed to achieve the high strength while retaining optimum impact strength of the DP steel.

scholarly journals FINE GRAINED DUAL PHASE STEEL BY THERMO MECHANICAL PROCESSING

2013 ◽  
pp. 237-240
Author(s):  
NEERAJAGARWAL NEERAJAGARWAL ◽  
G.P. CHAUDHARI ◽  
S.K. NATH
Keyword(s):  
Dual Phase Steel ◽  
Intercritical Annealing ◽  
Hsla Steel ◽  
Coarse Grained ◽  
Dual Phase ◽  
Mechanical Processing ◽  
Dp Steel ◽  
Fine Grained ◽  
Ultrafine Grained ◽  
Open Die Forging

The effect of thermo mechanical processing (TMP) on the mechanical properties of HSLA steel was investigated. TMP was conducted using a laboratory open die forging machine.Multiaxial forging (MAF) and intercritical annealing methods were used. TMP is designed to obtain ultrafine grained (UFG) steels. MAF is performed on prismatic shaped samples up to nine strain forging steps to produce ultra-fine grained (UFG) ferrite-pearlite steel with higher strength as compare to as received steel.Fine grained (FG) ferrite-martensite dual phases (DP) steel was fabricated by using combined effect of warm MAF and intercritical annealing. The tensile strength of FG-DP steels was much higher than that of the coarse-grained (CG) counterpart, and the uniform elongations were significantly enhanced. This steel exhibited the superior combination of higher strength and more rapid strain hardening compared to those of CG-DP steel was explained in terms of their specific microstructural features.

MITTAL DI-FORM T500

Alloy Digest ◽  
2006 ◽  
Vol 55 (9) ◽  
Keyword(s):  
Tensile Strength ◽  
Automotive Industry ◽  
Dual Phase Steel ◽  
High Strength ◽  
Martensite Phase ◽  
Ferrite Phase ◽  
Dual Phase ◽  
Advanced High Strength Steel ◽  
Automotive Body ◽  
Soft Ferrite

Abstract Mittal Di-Form T500 is a dual-phase steel intended primarily for exposed outer automotive body panels (door, hoods, and fenders). Dual-phase steels are one of the important advanced high-strength steel products developed for the automotive industry. Their microstructure typically consists of a soft ferrite phase with dispersed islands of a hard martensite phase. The martensite phase is substantially stronger than the ferrite phase. The Di-Form grades exhibit low yield-to-tensile strength ratios and the name corresponds to the tensile strength. This datasheet provides information on tensile properties as well as deformation and fatigue. It also includes information on forming and joining. Filing Code: SA-556. Producer or source: Mittal Steel USA Flat Products.

Effects of the Morphology and Distribution of Ferrite and Martensite on Mechanical Properties of Dual-Phases Steel

2013 ◽  
Vol 631-632 ◽  
pp. 404-411
Author(s):  
Jia Guo ◽  
Guo Sen Zhu ◽  
Zhi Qiang Yao ◽  
Jie Liu ◽  
Yu Du ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Impact Toughness ◽  
Yield Strength ◽  
Acicular Ferrite ◽  
Dual Phase Steel ◽  
Dual Phase ◽  
Dual Phase Steels ◽  
Dp Steel

The ingots were rolled by 550 mills in laboratory to obtain dual-phase steels. The influence of the morphology and distribution of ferrite and martensite on mechanical properties of dual-phase steel was investigated. The results indicated that some amount of acicular ferrite transformed in DP steel is available for decreasing the size and homogenizing the distribution of martensite in ferrite base. Meanwhile, the values of yield strength, tensile strength and impact toughness increases apparently, the value of elongation decreases to 22.5% .

Microstructure Evolution and Mechanical Properties of 780 MPa Hot Dip Galvanized Dual-Phase Steel

2010 ◽  
Vol 146-147 ◽  
pp. 1331-1335 ◽  
Author(s):  
Guo Bin Li ◽  
Zheng Zhi Zhao ◽  
Di Tang
Keyword(s):  
Mechanical Properties ◽  
Microstructure Evolution ◽  
Dual Phase Steel ◽  
Total Elongation ◽  
Annealing Process ◽  
Continuous Annealing ◽  
Dual Phase ◽  
Dp Steel ◽  
Gleeble 3500 ◽  
Soaking Temperature

The microstructure evolution of 780 MPa hot dip galvanized dual-phase (DP) steel at heating stages of the annealing process was analyzed using a Gleeble−3500 thermal/mechanical simulator. A multifunction continuous annealing simulator was employed to investigate the effect of annealing process on microstructure and mechanical properties of hot dip galvanized DP steel. The experimental results show that ferrite recovery and recrystallization, pearlite dissolution and austenite nucleation and growth take place in the annealing process of hot dip galvanized DP steel. The hardenability can be significantly improved by trace addition of vanadium. When the soaking temperature reaches 780 °C, the tensile strength and total elongation of DP steel can reach 785MPa and 15%, respectively. The microstructure of DP steel mainly consists of a mixture of ferrite and martensite.

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