Download or read book Liquid Metal Embrittlement of Advanced High Strength Steels During Resistance Spot Welding written by Julian Frei and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of Liquid Metal Embrittlement in Advanced High Strength Steels written by Liu He and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Third-generation advanced high strength steels (AHSS) are typically given a zinc coating that provides excellent resistance to corrosion. During the resistance spot welding (RSW) process, the melted zinc coating enables liquid metal embrittlement (LME) where the liquid zinc, acting as an embrittling agent, induces cracking in the weld indent, compromising weld strength. This work investigates the various factors that influence LME in AHSS and provides a viable solution to suppress LME. Hot tensile testing was first used to evalute the LME susceptiblility of the studied steels. It was discovered that the austenite content of the steels' microstructure, Si content in the steels' chemistry and the type of Zn coating all influence the behavior of the ductility trough of the examined steels. As the austenite content of the steel increased, the ductility loss caused by LME increased as well. Approximately 18 vol.% to 31 vol.% austenite is the minimum amount required to trigger the rise in ductility loss of all the studied steels. In addition, steels containing a low Si content are more likely to form a layer of Fe-Zn intermetallic that acts as a barrier to suppresses LME at temperatures below 670°C. It was also discovered that the GA coated steels are far less susceptible to LME than their GI coated counterparts due to it being thinner and containing 25 wt.% Fe in its coating. A mathematical model capable of estimating the crack index within the weld lobe of each material was also developed through resistance spot welding. The model showed that the weld lobe of materials where not equally affected by LME. Furthermore, it identified regions within the weld lobe where welds of sufficient size could be made while minimizing LME cracks. Using the hot tensile testing data and the results from RSW, LME susceptibility of the studied steels are ranked. QP1180GA is the most LME susceptible steel while DP980GA is the least. The ductility loss obtained via hot tensile testing shows good correlation with the intensity of LME cracks found in resistance spot welds. Finally, LME was suppressed in AHSS by placing aluminum interlayers added between the electrode and steel contact surface. Compared to welds exhibiting LME, TRIP 1100 with aluminum interlayers showed complete strength recovery while TRIP 1200 with aluminum interlayers resulted in a recovery of strength by 90%. Aluminum interlayers suppress LME of TRIP steel by formation of iron aluminides that hinder liquid zinc from coming in contact with the steel substrate, thus preventing LME.

Download or read book Liquid Metal Embrittlement Leading to Inner Cracks in Resistance Spot Welds written by Outhmane Siar and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced high strengths steels (AHSS) offer a good compromise between lightweight and high mechanical properties, allowing automotive parts to be made of thinner sheets and thus reducing CO2 emissions of vehicles. However, as they are composed with a higher amount of alloying elements, their resistance spot welding may be challenging and Liquid Metal Embrittlement (LME) is more likely to occur. LME cracks could appear at the surface (outer cracks) or at the interface between sheets (inner cracks). In the literature, many studies investigated outer cracks, but not the inner ones. This PhD thesis addresses the particular case of LME of a Gen.3 AHSS giving rise to inner cracks, when spot welded. First, the influence of severely deteriorated welding conditions on the occurrence of cracks has been studied. This allowed to underline a homogeneous welding configuration which produces significant LME inner cracks in a reproducible way. This first step allowed also to confirm the scarcity of these cracks and the possibility to avoid them by following standard welding conditions. In a second step, the impact of LME inner cracks on the mechanical behavior of spot welds has been investigated in cross tension, tensile shear and uniaxial tension. This concerned both their impact on the fracture mechanism and on the load bearing capacity of spot welds. With complementary tools including microscopic cross-section observations, 3D computed tomography and finite element simulation, it has been shown that the impact of such cracks remains globally non-critical except in the case of uniaxial loading. Finally, weld-bonding, a joining method defined by both the application of an adhesive and the spot weld formation, has been suggested as a possible solution to recover the observed losses. This solution has shown promising results in the case of tensile shear and remains to be tested in uniaxial tensile testing.

Download or read book A Statistical Approach to Quantifying Impact of Multiple Pulse Resistance Spot Welding Schedules on Liquid Metal Embrittlement Cracking written by Erica Wintjes and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced high strength steels (AHSS) are advantageous for automotive applications due to their excellent strength and ductility. However, when coated with zinc for corrosion protection, these steels are susceptible to liquid metal embrittlement (LME) during welding. In this work, a new metric was developed to quantify LME severity and this metric was used to study the influence of multiple pulse weld schedules on LME cracking in resistance spot welds. Several conflicting reports have been released about the effect of LME on mechanical performance of resistance spot welds. In this work, a new method of LME crack quantification called a "Crack Index" was developed to link LME crack distributions in resistance spot welds to weld performance. The crack index is calculated by multiplying the lognormal median crack length by the number of cracks per weld and dividing by the sheet thickness. Because studies have established both crack size and location as vital factors affecting weld strength, both of these factors must be taken into account when characterizing LME severity. Lognormal median crack length is used as the parameter for crack size because the crack lengths measured in LME affected welds were observed to fit a lognormal distribution. Number of cracks is used to account for the probability that a crack may be found in a critical location and sheet thickness is used as a normalization factor. The crack index has a linear relationship with weld strength loss. The crack index analysis method was used to study the influence of multiple pulse welding schedules on LME severity. Pulsing was applied using two different methodologies: pulsing during the welding current to manage heat generation and a pre-pulse before the welding current to remove the zinc coating. All welds made using a double-pulse welding schedule exhibited less severe LME cracking than those made with a single pulse schedule with a similar nugget diameter. A double-pulse schedule with two equal length pulses showed the least severe LME cracking and a schedule consisting of a short pulse followed by a long pulse resulted in the most severe LME. This is due to both a difference in the amount of free zinc available for LME and the different thermal and stress profiles of the pulsing conditions. The majority of pre-pulse welding schedules caused an increase in LME cracking due to the additional heat introduced into the weld. However, a 4 kA pre-pulse (low current), applied for 3 cy (low time) was able to reduce LME cracking in TRIP1100, a LME crack susceptible alloy, by almost 30%. The 4 kA, 3 cy pre-pulse reduced the amount of free zinc for LME, without introducing too much additional heat into the weld.

Download or read book TMS 2022 151st Annual Meeting Exhibition Supplemental Proceedings written by The Minerals, Metals & Materials Society and published by Springer Nature. This book was released on 2022-03-11 with total page 1597 pages. Available in PDF, EPUB and Kindle. Book excerpt: This collection presents papers from the 151st Annual Meeting & Exhibition of The Minerals, Metals & Materials Society.

Download or read book Towards Understanding the Effects of Current Input on Fatigue Mechanisms in Resistance Spot Welding of Advanced High Strength Steels written by Conner Cleek and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, the relationship of welding parameters to fatigue mechanisms is examined in spot welding of advanced high strength steels. Lightweighting efforts in the automotive industry are part of a push for greater fuel economy and improved consumer safety. TBF-1180 is an advanced high strength steel being developed for use in structurally critical components, however its fatigue behavior is not well understood. Electro galvanized TBF-1180 possesses corrosion resistant properties, however the additional zinc layer allows for the possibility of zinc-penetrative liquid metal embrittlement (LME) to occur during resistance spot welding (RSW). Additionally, variations in weld input and correspondingly heat input can affect the performance of welds due to microstructural changes that occur. In this study, the effect of LME and changes in microstructure were assessed in separate experiments for their fatigue impact in TBF-1180. Welds were fabricated in a traditional lap shear geometry in order to investigate the effects of LME, while an hourglass shaped cap geometry was used for welds with microstructural variation. Fatigue testing revealed that for lap-shear coupons containing LME cracks, no deleterious effect was observed. Cap geometry specimens were assessed for performance in a control and a high-current low-time condition, and a significant fatigue knockdown factor was found. Post-mortem fractography on both specimen geometries revealed that fatigue cracks initiated at the inner faying surface, regardless of the presence of LME. Finite element analysis confirmed that the LME cracks in the lap shear weld experience compressive stresses during loading, contributing to the lack of fatigue impact. Experimental conditions used for the cap geometry had lower heat input, which can result in less retained metastable austenite after welding, leading to reduced crack growth resistance. To tests the hypothesis that less retained metastable austenite after welding can cause a reduction in the number of cycles to failure in the spot weld, life prediction were made using fracture mechanics concepts coupled with reported knockdown factors on crack growth rates in relation to the amount of transformed martensite. The life predictions generated with this method strongly matched the observed fatigue behavior for the cap geometry specimens.

Download or read book Welding and Joining of Advanced High Strength Steels AHSS written by Mahadev Shome and published by Elsevier. This book was released on 2015-02-25 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt: Welding and Joining of Advanced High Strength Steels (AHSS): The Automotive Industry discusses the ways advanced high strength steels (AHSS) are key to weight reduction in sectors such as automotive engineering. It includes a discussion on how welding can alter the microstructure in the heat affected zone, producing either excessive hardening or softening, and how these local changes create potential weaknesses that can lead to failure. This text reviews the range of welding and other joining technologies for AHSS and how they can be best used to maximize the potential of AHSS. - Reviews the properties and manufacturing techniques of advanced high strength steels (AHSS) - Examines welding processes, performance, and fatigue in AHSS - Focuses on AHSS welding and joining within the automotive industry

Download or read book The Metallurgy of Zinc Coated Steels written by Arnold Marder and published by Elsevier. This book was released on 2023-02-22 with total page 610 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Metallurgy of Zinc Coated Steels provides a comprehensive overview of the science and engineering of zinc coatings. Beginning with a look at new innovations made in the hot-dip coating methods (CGL), the book goes on to discuss phase equilibria, Zn bath phenomena and overlay coating formations. Both processing methods and controls are covered, as well as corrosion resistance and coating product properties. The book concludes with a discussion of future opportunities for zinc coatings. This book is a vital resource for both individuals new to this area while also serving as a handbook for users and producers of zinc coatings. - Presents a basic understanding of the science and engineering behind zinc coatings with a thorough and cutting-edge look at their processing methods, controls, properties, and applications - Discusses corrosion resistance, overlay coating formation, heat treatment, interface reactions, deposition processes, and more - Covers real-world applications of these coatings

Download or read book New Advanced High Strength Steels written by Mohamed Goune and published by John Wiley & Sons. This book was released on 2024-01-11 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, significant developments have been made to increase the mechanical strength of steels in order to reduce the overall weight of structures, particularly in motor vehicles. Depending on the application, the increase in strength should not be at the expense of forming and in-use properties. The development of ultra-high strength steels requires a search for new trade-offs between these properties in order to optimize the final microstructure. New Advanced High Strength Steels analyzes the interactions between tensile mechanical properties and properties such as work hardening, anisotropy, resistance to rupture, fatigue life, corrosion resistance, crashworthiness, edge retention, hydrogen resistance and weldability. It also examines the links between the microstructural parameters of high-strength steels and the properties mentioned above. It highlights the metallurgical developments that have been necessary for the emergence of these new generations of steels. The book concludes with a look ahead to future developments in ultra-high strength steels

Download or read book Hot Dip Galvanizing of Steel Structures written by Vlastimil Kuklik and published by Butterworth-Heinemann. This book was released on 2016-02-09 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hot-Dip Galvanizing of Steel Structures contains practical information that is useful for both researchers in hot-dip galvanizing and engineers, designers, and inspectors. The book draws from the empirical experience and research of the authors, complementing the current state of knowledge of morphological variations of the coating and causes of coating delamination. The book includes chapters devoted to qualitative tests of the coating, and to methods of making corrections. A section describing the principle of protecting steel against corrosion through zinc coating is also provided, along with an extensive chapter on the principles of good design for hot-dip galvanizing. The chapter related to the safety of hot-dip galvanized steel structures offers a new hypothesis about the mechanism of nucleation of LMAC cracks during hot-dip galvanizing, thus enriching the knowledge regarding this phenomenon. - Provides practical information on hot-dip galvanizing from a scientific-disciplinary perspective, including coverage of design principles, reliability of galvanized structures, and legal aspects - Features chapters devoted to qualitative assessments of the surface treatment and methods for correcting problems - Includes discussion of hot-dip galvanizing with regard to environmental aspects and sustainable development

Download or read book Transactions on Intelligent Welding Manufacturing written by Shanben Chen and published by Springer. This book was released on 2018-05-07 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary aim of this volume is to provide researchers and engineers from both academia and industry with up-to-date coverage of recent advances in the fields of robotic welding, intelligent systems and automation. It gathers selected papers from the 2017 International Workshop on Intelligentized Welding Manufacturing (IWIWM’2017), held June 23-26, 2017 in Shanghai, China. The contributions reveal how intelligentized welding manufacturing (IWM) is becoming an inescapable trend, just as intelligentized robotic welding is becoming a key technology. The volume is divided into four main parts: Intelligent Techniques for Robotic Welding, Sensing in Arc Welding Processing, Modeling and Intelligent Control of Welding Processing, and Intelligent Control and its Applications in Engineering.

Download or read book Microstructure and Texture in Steels written by Arunansu Haldar and published by Springer Science & Business Media. This book was released on 2009-09-03 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microstructure and Texture in Steels and Other Materials comprises a collection of articles pertaining to experimental and theoretical aspects of the evolution of crystallographic texture and microstructure during processing of steels and some other materials. Among the topics covered is the processing-microstructure-texture-property relationship in various kinds of steels, including the latest grade. Special emphasis has been given to introduce recent advances in the characterization of texture and microstructure, as well as modeling. The papers included are written by well-known experts from academia and industrial R and D, which will provide the reader with state-of-the-art, in-depth knowledge of the subject. With these attributes, Microstructure and Texture in Steels and Other Materials is expected to serve the cause of creating awareness of current developments in microstructural science and materials engineering among academic and R and D personnel working in the field.

Download or read book Resistance Welding written by Hongyan Zhang and published by CRC Press. This book was released on 2011-12-13 with total page 465 pages. Available in PDF, EPUB and Kindle. Book excerpt: Drawing on state-of-the-art research results, Resistance Welding: Fundamentals and Applications, Second Edition systematically presents fundamental aspects of important processes in resistance welding and discusses their implications on real-world welding applications. This updated edition describes progress made in resistance welding research and

Download or read book Failure Analysis of Heat Treated Steel Components written by Lauralice de Campos Franceschini Canale and published by ASM International. This book was released on 2008 with total page 651 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of Liquid Metal Embrittlment in Advanced High Strength Steels written by Nathaniel P. Briant and published by . This book was released on 2018 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis explored the susceptibility of ferritic/bainitic, advanced high strength steels to zinc-based liquid metal embrittlement (LME). The understanding of the causes and effects of LME is critical because of the common use of zinc coatings for corrosion protection and an increased used of advanced high strength steels in industries such as automotive. Transformation induced plasticity steels, TBF 1180 and TRIP 700, and a complex phase steel, CP 1200, were studied to assess their susceptibility to LME during hot tensile tests. Comparisons between stress versus strain curves collected with and without zinc coatings at various temperatures and strain rates were used to determine the effect of the zinc-based embrittlement on the mechanical properties of these steels. The stress versus strain curves were collected using uniaxial hot tensile tests in a Gleeble 1500D thermal-mechanical simulator from Dynamic Systems Inc. The fracture modes were studied using scanning electron microscopy and energy-dispersive X-ray spectrometry (EDS). From the results it was determined that all three steels demonstrated LME at temperatures between 800 degrees C and 900 degrees C and nominal strain rates of 1.3 and 0.13 strain per second. The fracture mode for all LME cracks was found to be intergranular.

Download or read book Manufacturing and Application of Stainless Steels written by Andrea Di Schino and published by MDPI. This book was released on 2020-04-15 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stainless steels represent a quite interesting material family, both from a scientific and commercial point of view, following to their excellent combination in terms of strength and ductility together with corrosion resistance. Thanks to such properties, stainless steels have been indispensable for the technological progress during the last century and their annual consumption increased faster than other materials. They find application in all these fields requiring good corrosion resistance together with ability to be worked into complex geometries. Despite to their diffusion as a consolidated materials, many research fields are active regarding the possibility to increase stainless steels mechanical properties and corrosion resistance by grain refinement or by alloying by interstitial elements. At the same time innovations are coming from the manufacturing process of such a family of materials, also including the possibility to manufacture them starting from metals powder for 3D printing. The Special Issue scope embraces interdisciplinary work covering physical metallurgy and processes, reporting about experimental and theoretical progress concerning microstructural evolution during processing, microstructure-properties relations, applications including automotive, energy and structural.

Download or read book Advanced Steels written by Yuqing Weng and published by Springer Science & Business Media. This book was released on 2011-04-14 with total page 495 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Advanced Steels: The Recent Scenario in Steel Science and Technology" contains more than 50 articles selected from the proceedings of the International Conference on Advanced Steels (ICAS) held during 9-11, Nov, 2010 in Guilin, China. This book covers almost all important aspects of steels from physical metallurgy, steel grades, processing and fabrication, simulation, to properties and applications. The book is intended for researchers and postgraduate students in the field of steels, metallurgy and materials science. Prof. Yuqing Weng is an academician of Chinese Academy of Engineering and the president of The Chinese Society for Metals. Prof. Han Dong is the vice president of Central Iron & Steel Research Institute and the director of National Engineering Research Center of Advanced Steel Technology, China. Prof. Yong Gan is an academician of Chinese Academy of Engineering, the vice president of Chinese Academy of Engineering and the president of Central Iron & Steel Research Institute, China.