scholarly journals HAZ Characterization of Automotive DP Steels by Physical Simulation

2019 ◽  
Vol 4 (1) ◽  
pp. 478-487
Author(s):  
Raghawendra Sisodia ◽  
Marcell Gáspár ◽  
Noureddine Guellouh
Keyword(s):  
Co2 Emission ◽  
Physical Simulation ◽  
Weight Ratio ◽  
High Strength ◽  
Steel Grade ◽  
Cooling Time ◽  
Dp Steel ◽  
Dp Steels ◽  
Gleeble 3500

DP steels were extensively used in the vehicles industry due to its extraordinary combined properties of strength, ductility, formability and weldability which contributed great significance in reducing strength to weight ratio and CO2 emission. High strength steel i.e. DP steels (3 different grades) were experimentally investigated and thermophysically simulated using Gleeble 3500 simulator to determine softening and hardening in heat affected zone. Samples were heated to different peak temperatures (1350 °C, 950 °C, 775 °C and 650 °C), two cooling time (t8.5/5 = 5 s and 30 s) and Rykalin 2D model were selected. The hardness and microstructure of the specimens were tested and analysed. For longer cooling time (t8.5/5= 30 s), we observed that softening occurs in all grade of investigated DP steels to all sub-regions. But for shorter cooling time i.e. t8.5/5= 5 s the softening is higher in intercritical HAZ compared to other sub-regions for all the types of DP steel with short cooling time (t8.5/5 = 5 s). However, the hardening zone in the CGHAZ occurs when Tmax is 1350 ºC for DP600, DP800 & DP1000 steels but it is more prominent in DP800 as compared to others two steel grade.

Physical Simulation of Weldability of Weldox 1300 Steel

2013 ◽  
Vol 762 ◽  
pp. 551-555 ◽  
Author(s):  
Marek Stanislaw Węglowski ◽  
Marian Zeman ◽  
Miroslaw Lomozik
Keyword(s):  
Mechanical Properties ◽  
Impact Toughness ◽  
Physical Simulation ◽  
High Strength ◽  
Parent Material ◽  
Cooling Time ◽  
Electron Microscopies ◽  
Transmission Electron ◽  
Transformation Diagrams ◽  
The Impact

In the present study, the investigation of weldability of new ultra-high strength - Weldox 1300 steel has been presented. The thermal simulated samples were used to investigate the effect of welding cooling time t8/5 on the microstructure and mechanical properties of the heat affected zone (HAZ). In the frame of these investigation the microstructure was studied by the light (LM) and transmission electron microscopies (TEM). It has been shown that the microstructure of the Weldox 1300 steel is composed of tempered martensite, and inside the laths the minor precipitations mainly V(CN) and molybdenum carbide Mo2C were observed. Mechanical properties of parent material were analysed by the tensile, impact and hardness tests. In details the influence of cooling time in the range of 2,5 - 300 s. on hardness, impact toughness and microstructure of simulated HAZ was studied by using welding thermal simulation test. The results show that the impact toughness and hardness decrease with the increase of t8/5 under the condition of a single thermal cycle in simulated HAZ. The continuous cooling transformation diagrams (CCT-W for welding conditions) of Weldox 1300 steel for welding purposes was also elaborated. The steel Weldox 1300 for cooling time in the range of 2,5 - 4 s showed martensite microstructure, for time from 4 s to 60 s mixture of martensite and bainite, and for longer cooling time mixture of ferrite, bainite and martensite. The results indicated that the weldability of Weldox 1300 steel is limited and to avoid the cold cracking the preheating procedure or medium net linear heat input should be used.

Microstructural Characterization of α2 + γ Titanium Aluminides

1997 ◽  
Vol 3 (S2) ◽  
pp. 701-702
Author(s):  
D. J. Larson ◽  
M. K. Miller
Keyword(s):  
Titanium Aluminides ◽  
Base Alloy ◽  
Significant Proportion ◽  
Weight Ratio ◽  
High Strength ◽  
Microstructural Characterization ◽  
Two Phase ◽  
Tial Alloys ◽  
Boron Doped

Two-phase α2+γ TiAl alloys with microalloying additions, Fig. 1, are of interest due to the high strength-to-weight ratio they can provide in automotive and aircraft applications. In boron-doped α2+γTiAl containing Cr, Nb, and W, the B levels were found to be significantly depleted below the nominal alloy content in both the α2 andγ phases. The boron solubilities in the γ and α2 phases were 0.011 ± 0.005 at. % B and 0.003 ± 0.005 at. % B, respectively in Ti-47% Al-2% Cr-1.8% Nb-0.2% W-0.15 % B that was aged for 2 h at 900°C (base alloy). The majority of the B was in a variety of borides including TiB, TiB2 and a Cr-enriched (Ti,Cr)2B precipitate. With the exception of the smaller (< 50 nm thick) Cr-enriched (Ti,Cr)2B precipitates, Fig. 2, most of the borides were larger than ∼100 nm. A significant proportion of the microalloying additions is in these borides, Table 1.

Quasi-static crack propagation in Ti-6Al-4V in inert and aggressive media

2019 ◽  
Vol 37 (5) ◽  
pp. 533-538
Author(s):  
Sergio Baragetti ◽  
Emanuele Borzini ◽  
Emanuele Vincenzo Arcieri
Keyword(s):  
Corrosion Resistance ◽  
Surface Layer ◽  
Static Loading ◽  
Weight Ratio ◽  
High Strength ◽  
Surface Oxide Film ◽  
Notch Geometry ◽  
Consequent Reduction ◽  
Corrosive Environments

AbstractHigh strength-to-weight ratio Ti-6Al-4V alloy is used in many engineering applications. Its surface oxide film can protect the substrate from interaction with a lot of corrosive environments. Unfortunately, this surface layer can be damaged under mechanical and chemical actions with a consequent reduction in corrosion resistance. A characterization of the untreated alloy under quasi-static loading is here provided. Inert and aggressive environments have been investigated and the influence of the notch geometry of the alloy has also been analyzed.

scholarly journals Implementation of the ultrasonic through-transmission technique for the elastic characterization of fiber-reinforced laminated composite

DYNA ◽  
2019 ◽  
Vol 86 (208) ◽  
pp. 153-161
Author(s):  
Carlos A. Meza ◽  
Ediguer E. Franco ◽  
Joao L. Ealo
Keyword(s):  
Laminated Composites ◽  
Weight Ratio ◽  
Laminated Composite ◽  
High Strength ◽  
Mechanical Tests ◽  
Fiber Reinforced ◽  
Transmission Technique ◽  
Laminated Materials

Laminated composites are widely used in applications when a high strength-to-weight ratio is required. Aeronautic, naval and automotive industries use these materials to reduce the weight of the vehicles and, consequently, fuel consumption. However, the fiber-reinforced laminated materials are anisotropic and the elastic properties can vary widely due to non-standardized manufacturing processes. The elastic characterization using mechanical tests is not easy, destructive and, in most cases, not all the elastic constants can be obtained. Therefore, alternative techniques are required to assure the quality of the mechanical parts and the evaluation of new materials. In this work, the implementation of the ultrasonic through-transmission technique and the characterization of some engineering materials is reported. Isotropic materials and laminated composites of carbon fiber and glass fiber in a polymer matrix were characterized by ultrasound and mechanical tests. An improved methodology for the transit time delay calculation is reported.

Role of the Physical Simulation for the Estimation of the Weldability of High Strength Steels and Aluminum Alloys

2015 ◽  
Vol 812 ◽  
pp. 149-154 ◽  
Author(s):  
János Lukács ◽  
László Kuzsella ◽  
Zsuzsanna Koncsik ◽  
Marcell Gáspár ◽  
Ákos Meilinger
Keyword(s):  
Physical Simulation ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Test Methods ◽  
Hot Cracking ◽  
Simulation Test ◽  
Gleeble 3500 ◽  
Welding Processes

The physical simulation is an ultimate innovative way to develop the welding processes. The paper introduces the connection between weldability and physical simulation, hot-cracking sensibility, the Gleeble 3500 thermo-mechanical physical simulator, respectively. Four kinds of materials were investigated and different kinds of physical simulation test methods were made such as, identification of the Nil-Strength Temperature (NST), hot tensile tests (on heating and on cooling parts of the welding simulation curve are also investigated). Furthermore, Heat Affected Zone (HAZ) tests are being introduced. The future approaches of the research are also exposed.

Synthesis and Characterization of Al/Al3Fe Nanocomposite for Tribological Applications

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Rahul Agarwal ◽  
Anita Mohan ◽  
Sunil Mohan ◽  
Rakesh Kr. Gautam
Keyword(s):  
Linear Thermal Expansion ◽  
Density Measurement ◽  
Aluminum Matrix ◽  
Weight Ratio ◽  
Physical And Mechanical Properties ◽  
High Strength ◽  
Mechanical And Physical Properties ◽  
Bulk Hardness ◽  
Matrix Nanocomposites

Aluminum based composites find diverse applications due to their superior mechanical and physical properties. Aluminum matrix nanocomposites have been synthesized with Al3Fe nanocrystalline intermetallics reinforcement using the powder metallurgy route. The prepared composites have been characterized for various physical and mechanical properties such as density measurement, bulk hardness, compressive strength, and tribological properties. The theoretical coefficient of the linear thermal expansion has also been predicted. The composite shows a high strength to weight ratio and excellent wear resistance, along with a low coefficient of friction. The observed wear rate is superior to other composites irrespective of the load and sliding velocity chosen for the study and it continuously decreases withan increasing amount of dispersoid.

Microstructure Characterization of Deep-Drawn DP780-Grade Dual Phase Steel

2013 ◽  
Vol 752 ◽  
pp. 75-84
Author(s):  
Adám Filep ◽  
Valéria Mertinger
Keyword(s):  
Dual Phase Steel ◽  
Annealing Temperature ◽  
Crack Formation ◽  
Intercritical Annealing ◽  
High Strength ◽  
Rolled Sheet ◽  
Dual Phase ◽  
Hsla Steels ◽  
Dp Steels

Dual phase (DP) steels belong to the group of high-strength low-alloy (HSLA) steels. Our study focuses on the causes of crack formation of sheets, which are designed for deep drawing, of DP780-grade dual phase steel. Also, a series of heat treatment experiments were performed regarding the effect of intercritical annealing temperature on the structure and mechanical properties of the finished product (in this case a rolled sheet).

scholarly journals Characterization of bainite-ferrite structures formed on the heat-affected zone of a dissimilar welds of high-strength steel (S700MC/S960QC) and their dependency on cooling time

2020 ◽  
Vol 65 (4) ◽  
pp. 159-172
Author(s):  
Bayock Njock ◽  
Paul Kah ◽  
Belinga Mvola ◽  
Pavel Layus ◽  
Xiaoyu Cai
Keyword(s):  
Heat Affected Zone ◽  
Volume Fraction ◽  
High Strength Steels ◽  
Steel Structures ◽  
High Strength ◽  
Cooling Time ◽  
Granular Bainite ◽  
High Yield ◽  
Dissimilar Welding

Modern steel structures and joints must satisfy various increasingly demanding requirements such as high yield strength, improved cross section to mass ratio, and desirable ductile-to-brittle transition properties. Consequently, joining different types of high-strength steels has become an attractive option from the cost perspective and for weight and corrosion reduction. In dissimilar welding, however, there remains a need for better understanding of discrepancies in microstructure formation resulting from asymmetric heat distribution. In this study, a characterization of the transformation of bainite, ferrite, and martensite in the microstructure of the heat affected zone (HAZ) formed by a cooling time of 10 kJ/cm of heat input was carried out for dissimilar high-strength joint steels (S700MC/S960QC). The characterization was performed by scan electron microscopy (SEM) sampling, the images of which were analyzed by ImageJ Pro and evaluated by volume fraction of block - like granular bainite (GB). The alloy elements composition close to the fusion line of both materials was then assessed using energy dispersive X-ray spectroscopy (EDS). The results showed a strong presence of GB, which had about 70% volume fraction in S700MC at 615 °C, and which comprised formations of lower bainite and retained austenite (RA) at 420 °C. The presence of 55% block GB was observed at 470 °C in S960QC, which was caused by the formation of tempered martensite (TMA) at 400 °C. Presence of 1.3Ni, 0.4Mo, and 1.6Mn in the coarse grain heat affected zone (CGHAZ) of S700MC confirmed the risk of brittle failure on the S700MC side due to the high presence of carbide and ferrite in the GB.

Precipitation in Al-Li-Zr alloys

1992 ◽  
Vol 50 (1) ◽  
pp. 186-187
Author(s):  
D.M. Vanderwalker
Keyword(s):  
Fracture Toughness ◽  
Precipitation Hardening ◽  
Weight Ratio ◽  
High Strength ◽  
Transmission Electron ◽  
Water Quench ◽  
Aluminum Lithium ◽  
Aluminum Lithium Alloys ◽  
Lithium Alloys ◽  
Zr Alloys

Aluminum-lithium alloys have a low density and high strength to weight ratio. They are being developed for the aerospace industry.The high strength of Al-Li can be attributed to precipitation hardening. Unfortunately when aged, Al-Li aquires a low ductility and fracture toughness. The precipitate in Al-Li is part of a sequence SSSS → Al3Li → AlLi A description of the phases may be found in reference 1 . This paper is primarily concerned with the Al3Li phase. The addition of Zr to Al-Li is being explored to find the optimum in properties. Zirconium improves fracture toughness and inhibits recrystallization. This study is a comparision between two Al-Li-Zr alloys differing in Zr concentration.Al-2.99Li-0.17Zr(alloy A) and Al-2.99Li-0.67Zr (alloy B) were solutionized for one hour at 500oc followed by a water quench. The specimens were then aged at 150°C for 16 or 40 hours. The foils were punched into 3mm discs. The specimens were electropolished with a 1/3 nitric acid 2/3 methanol solution. The transmission electron microscopy was conducted on the JEM 200CX microscope.

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