Antonio J Ramirez

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• Ph.D. Materials Science
• Professor at The Ohio State University

This work addressed the stress corrosion cracking (SCC) resistance of welded ultra-high-strength steel (UHSS) using gas metal arc welding (GMAW) with ER100 and ER120 filler metals. The microstructure of welds was characterized, and SCC resistance assessed using slow strain rate to compare the percentage of elongation at failure (pct EL) when testin...

Nickel-based alloys, Alloys 625 and 718, are widely used in the aerospace industry due to their excellent corrosion resistance and high strength at elevated temperatures. Recently, these alloys have been utilized to manufacture rocket engine components using additive manufacturing (AM) technologies such as laser powder bed fusion (LPBF) and powder-...

Restoring components in the hot gas path of turbine engines after service-induced degradation is crucial for economic efficiency. This study investigates the printability of Rene 65 powder on a degraded first-stage turbine blade using two additive manufacturing techniques: Laser Powder Bed Fusion (L-PBF) and Laser Powder Directed Energy Deposition...

The use of laser powder bed fusion (LPBF) for faster and more customized manufacturing has grown significantly. However, LPBF parts often require welding to other components, raising concerns about their weldability due to differences in microstructure compared to conventionally manufactured parts. Despite its importance, research on the weldabilit...

Wire arc additive manufacturing (WAAM) is an effective technique for producing medium to large-size components, due to its convenience and sustainability in fabricating large-scale parts with high deposition rates, employing low-cost and simple equipment, and attaining high material efficiency. Thus, WAAM attracts different industrial sectors and h...

title>ABSTRACT The US Army TARDEC has been researching an alternative to current armor steel that is both tough, and light-weight. The studied alloy is based on the Fe-Mn-Al-C system. This study was conducted to investigate and quantify this alloy’s susceptibility to hot cracking phenomena related to casting and welding. Very little research has b...

title>Abstract The United State Army employs several advanced armored combat vehicles, in a wide array of different environments, and applications. Armor steels are hard and are required to meet certain conditions to stay within the military’s specifications for armored steels. Vehicle armor is typically joined using arc welding methods. Joining v...

Solidification cracking (SC) is a defect that occurs in the weld metal at the end of the solidification. It is associated with the presence of mechanical and thermal stresses, besides a susceptible chemical composition. Materials with a high solidification temperature range (STR) are more prone to the occurrence of these defects due to the formatio...

Super Duplex stainless steels (SDSS) are alloys based on the Fe-Cr-Ni-N system. The chemical composition is tailored to achieve a balanced microstructure of 50% ferrite and 50% austenite. Hyper Duplex Stainless Steels (HDSS) are also duplex materials distinguished by their remarkable yield strength (≥700 MPa) and corrosion resistance (PREN>48). The...

This work uses kinetics calculation and a thermomechanical physical simulator to evaluate the sigma phase precipitation in Hyper Duplex Stainless Steel (HDSS) as-welded microstructure for impact toughness evaluation. Precipitation bars were machined out of a HDSS deposited clad mockup and submitted through aging on the thermomechanical physical sim...

This study focuses on the kinetic analysis of sigma phase formation in filler metal wires on Super Duplex Stainless Steel (SDSS) and Hyper Duplex Stainless Steel (HDSS). Precipitation data reveal that in the solubilized microstructure, sigma phase kinetics are more prominent in SDSS. This increased susceptibility is attributed to the greater number...

Wire arc additive manufacturing (WAAM) is an efficient technique for producing medium to large‐size components, due to its accessibility and sustainability in fabricating large‐scale parts with high deposition rates, employing low‐cost and simple equipment, and achieving high material efficiency. Consequently, WAAM has garnered attention across var...

FeMnAl steels are currently generating a lot of interest with potential applications for structural parts in armored vehicles due to their lower density and outstanding mechanical properties. Despite the extensive mechanical performance and heat treatment exploration of this alloy class, further weldability investigation is required for future larg...

Additive manufacturing (AM) has the potential for improving the sustainability of metal processing through decreased energy and materials usage compared to casting and forging. Laser powder bed fusion (LPBF) of high-temperature alloys such as nickel alloy 718 is one of the key modalities supporting this effort. One of the major drawbacks to LPBF is...

In-service welding simulations were carried out using a multiphysics finite element analysis (FEA). Calculated data as temperature and thermal cycles were validated by comparing them with experimental welding results carried out in a carbon steel pipe attached to a water loop. Two in-service welding cases were tested using the GMAW-P process with a...

Repair of in-service O&G pipelines is an important demand worldwide. • Experimental and numerical analysis of inservice welding was used to assess the application of GMAW-P DC/AC assisted with induction preheating (IP). • A multiphysics FEM-based model was developed considering: heat transfer, fluid flow, and electromagnetic field. • The GMAW-P DC...

A finite element model was developed using a multiphysics finite element analysis (FEA) coupling heat transfer, fluid flow, and electromagnetic heating. Part 1 presents the software implementation and model equations beside the mesh setting and modeling approach to simulate circumferential welding of Type B sleeve repair. The simulation was divided...

This study investigates and compares the kinetics of sigma phase formation in established Super Duplex Stainless Steel (SDSS) and recently developed Hyper Duplex Stainless Steel (HDSS) filler metal wires. Experimental sigma phase time-temperature-transformation (TTT) maps were developed, revealing nearly equivalent interface area/volume, resulting...

This work discusses several aspects of the weldability of AA5083-H116 butt-welded joints, using ER5183 filler material, automated GMAW-P process, and 80Ar19He1O2 shielding gas. The used methodology included the characterization of base metal, the development of welded joints using two different heat inputs, the microhardness profiles analysis on th...

Coke drums are critical units in the delayed coking process to produce lightweight oil products from heavy residual oil. The fulfillment of the designed coke drum lifetime is often obstructed by low-cycle fatigue damage over cyclic thermal and mechanical loading. Considering the tremendous cost of drum replacement and production loss due to shutdow...

The Hyper Duplex Stainless Steel HDSS enhanced corrosion resistance and toughness relies upon high alloying to obtain a balanced ferrite and austenite volume and pitting resistance equivalent number PREn. However, during welding, sigma phase precipitates might form, hindering corrosion and mechanical performance. Therefore, a kinetics model is deve...

Additive Manufacturing (AM) has the potential for improving sustainability of metal processing through decreased energy and materials usage compared to casting and forging. Laser powder bed fusion (LPBF) of high temperature alloys such as nickel alloy 718 is one of the key modalities supporting this effort. One of the major drawbacks to LPBF is its...

GTAW welding with pulsed current has been misinterpreted in some of the classic literature and scientific articles. General conclusions are presented, stating that its use provides greater penetration compared to the use of constant current and that the simple pulsation of the current promotes beneficial metallurgical effects. Therefore, this manus...

The objective of this work is to study the possibility of obtaining dense parts using water atomized AISI 316L steel powder in the L-PBF process. Despite its irregular, non-spherical, particle morphology, it has a significantly lower cost. 25 samples were produced varying the laser power and the scanning speeds to determine the optimal processing c...

The deformation and fracture behaviors of undeformed-coarse (UC) and deformed-refined (DR) pearlitic steel microstructure were investigated via in-situ tensile-shear (TS) test in scanning electron microscopy (SEM). An original TS sample geometry was designed. Secondary Electron (SE) images were recorded in real-time and digital image correlation te...

The GTAW welding with pulsed current has been misinterpreted in some classic literature and scientific articles. General conclusions are presented, stating that its use provides greater penetration compared to the use of constant current and that the simple pulsation of the current promotes beneficial metallurgical effects. Therefore, this manuscri...

This work presents a kinetic study of the sigma phase formation in hyper duplex stainless steel filler metal. Two sigma phase precipitation kinetics models were developed and compared. Initially, experimental sigma phase precipitation was built using isothermal heat treatments with durations from 30 s to 600 s, and temperatures between 600 °C and 1...

Austenitic and ferritic stainless-steel interlayers for resistance spot welding of an AlSi-coated 2000MPa UTS press-hardened boron steel and a 6022-T4 aluminium alloy were investigated to improve joint performance. CALPHAD and kinetic-based simulations were explored to determine the effects of Cr on the formation of Fe–Al intermetallic compounds. S...

Alloy 625 is a Ni-based alloy used in aerospace, energy, chemical, oil and gas industries, mainly as cladding material due to its corrosion resistance, high strength and creep resistance at high temperature. In this study, microstructural evaluation and susceptibility to intergranular corrosion of base metal and friction stir welded Alloy 625 were...

Motorsport electrification raised the need to manufacture prototypes of battery packs. The manufacturing process requires welding many cylindrical cells to reach power and energy requirements. Cylindrical cells are made of steel and for this application, they are joined together using two layers of copper busbars. Dissimilar metals and significantl...

Welding repair has been widely used to restore the structural integrity of coke drums compromised by cracks due to low-cycle fatigue failure among other damaging mechanisms. Nevertheless, due to the heterogeneous mechanical and metallurgical properties, repair welds are susceptible to re-cracking during subsequent operations. The API 1996 report ha...

Strain accumulation as a result of cyclic loading affects the microstructure and mechanical performance of low-alloy steels under cyclic operation conditition. This manuscript presents a comprehensive analysis of a ferritic-pearlitic SA204 Grade C steel under strain-controlled low-cycle fatigue tests to understand the microstructural deformation an...

Cold spray and laser powder bed fusion deposition processes were explored and found to significantly increase the peak force and fracture energy of the press hardened boron steel–aluminium joint. The use of 250 µm thick 316L metallic interlayers was resistance spot welded to an AlSi-coated press hardened steel and 6022-T4 aluminium alloy. Moreover,...

Additive manufacturing (AM) has emerged as an outstanding technique for obtaining complex geometries and custom parts, without the material loss of conventional subtractive manufacturing processes. In this work, AISI 316L stainless steel specimens were fabricated by laser powder bed fusion (L-PBF), and its microstructure was characterized by severa...

After continuous annealing process (CAP) at 790°C, 85% of the coils of 50% cold-rolled low carbon microalloyed (LCM) steel did not exhibit yield-strength (YS) on the target range, while the 70% cold-reduced LCM coils did. In this context, the non-isothermal recrystallisation kinetics of ferrite for the above two full-hard LCM steel were investigate...

In this paper presents the phase stability and elemental partitioning in a Co-40Ni-10Al-7.5W-10Cr-3Nb-0.06B-0.6C (at.%) superalloy (referred to as 3Nb) after two-step heat treatment. The resultant microstructure consisted of γ, γ’, and MC carbide and µ-Co7W6 phase decorating regions near and at grain boundaries. Nb preferentially partitioned to γ’-...

NASA, defense, academia, and commercial space companies seek to develop orbital manufacturing to enhance mission capabilities. In-space welding and joining are needed for space-based manufacturing. We propose a permanent low-earth orbital welding and joining testbed for scientific study of relevant physical phenomena and development of welding and...

In-service welding in pipelines can be applied for repair and fittings installation purposes. One of the most important things in such application is the determination of the welding parameters, avoiding issues as hydrogen induced cracks (HIC), blow-out and fragile microstructures. Several different methods of in-service welding can be found, but t...

In-service welding in pipelines can be applied for repair and fittings installation purposes. One of the most important things in such application is the determination of the welding parameters, avoiding issues as hydrogen induced cracks (HIC), blow-out and fragile microstructures. Several different methods of in-service welding can be found, but t...

Low-cycle fatigue failure has been widely accepted as the key mechanism causing damages of coke drums during cyclic thermal-mechanical loadings. Common damages of coke drums known as bulging and cracking are associated with accumulative plasticity caused by thermal and mechanical strains. External repairs using temper-bead welding techniques are im...

Hyper Duplex Stainless Steels (HDSS) are dual phase, ferritic-austenitic materials with a remarkable yield strength (≥ 700 MPa) and corrosion resistance (PREN/W > 49). It has been developed as an alternative to super-duplex stainless steels, where higher mechanical and corrosion performance is required. Unfortunately, such highly alloyed materials...

The automotive industry is demanding more sophisticated resistance spot welding (RSW) models with an emphasis on integrated computational materials engineering (ICME) to better design welded structures. RSW process models are often validated using experimental weld nugget diameter measurements that verify the maximum temperature prediction but not...

Predicting the occurrence of solidification cracking during the solidification of metallic alloys by numerical simulation is a crucial move for avoiding such defects. Several models are widely available, however, the application of such are impacted due to the specific and not accessible parameters required. A simple, composition-based approach to...

Additive manufacturing (AM) has captured the imagination of the manufacturing community and has revolutionary potential across a number of energy applications. One particular challenge for these applications is the large size of metal AM components that are compelling to be printed. This necessitates welding and joining processes to integrate metal...

Coke drums are pressure vessels used in the delayed coking process at oil refineries, which transform heavy residual oil into light-weight hydrocarbon molecules and solid coke through thermal cracking. Due to the severe thermal and mechanical loadings during operation, these vessels experienced low-cycle fatigue failure, which led to shell and skir...

Temper bead (TB) welding is routinely used as an alternative to post weld heat treatment (PWHT) when performing weld repairs on low alloy steels in the nuclear power industry. Historically, TB welding procedures have been qualified by Charpy V-notch (CVN) testing to demonstrate acceptable impact properties in the weld heat affected zone (HAZ). Part...

The maximum allowed hardness for low carbon martensitic stainless steel components used in the oil and gas industry is 247 HV. Inter-critical tempering is an effective method for hardness control due to the production of stable reverted austenite. By conducting multiple-step tempering cycles, the austenite reversion kinetics can be accelerated and...

Bulk-metallic glasses (BMGs) are a class of structural materials with many attractive processing features such as the ability to be processed into parts with fine features, dimensional precision, and repeatability; however, their fracture behavior is complex and size-dependent. Previous work has shown that BMGs can display strong size effects on to...

In Situ Analysis of Cryoformed Metals by STEM - Volume 25 Supplement - Ricardo Sanson Namur, Daniel E. Huber, Antonio J. Ramirez, Osvaldo M. Cintho

Temper bead (TB) welding is often used as an alternative to post weld heat treatment (PWHT) for repair of pressure vessels and piping in the nuclear power industry. Historically, qualification of TB welding procedures has employed the Charpy V-notch test to ensure acceptable heat-affected-zone (HAZ) impact properties. The 2004 Edition of ASME Secti...

This work addresses the fundamentals of inter-critical austenite reversion in a Ti-stabilized 12Cr-6Ni-2Mo (at.%) supermartensitic stainless steel, combining thermodynamic and experimental assessments. The calculation of the temperature and composition at which ferrite and austenite phases have the same free energy, i.e. T0 and C0(T), respectively,...

Many models have been developed to explore solidification segregation and dendrite structure in additively manufactured parts. However, these models tend to be computationally expensive and consider only a limited number of alloying elements, compromising their practical application. In this work, a methodology to extend the Scheil model, based on...

A hybrid joining technique utilized resistance spot welding and friction element welding to produce a steel-aluminum multi-stack. Each weld process was tested independently and as a combination to better understand how multi-step welding affects joint performance. Weld interfaces and surrounding heat affected zones were investigated using microstru...

In the last paragraph of the section “SOLIDIFICATION AND THERMODYNAMIC SIMULATIONS”, the authors would like to change the sentence “Although the solvus temperature for δ was not predicted here, it should be near the non-equilibrium solidus temperature as it forms during the terminal stages of solidification” to “Although the solvus temperature for...

Dissimilar metal resistance spot welds, critical to the manufacture of medical devices, typically form brittle intermetallic compounds that are prone to failure. Here, a case study of biocompatible metals platinum and niobium using advanced analytical techniques is presented. It describes the variation of properties and microstructure using microre...

The ability to consolidate parts in complex assemblies using metal additive manufacturing offers transformational product development opportunities. Specifically, the high value capability for printing complex shapes and channels using metal laser powder bed fusion is a key enabler to realizing this vision. A thorough understanding of microstructur...

The thermal cycles associated to friction stir welding and processing produce a wide range of microstructures, resulting in different mechanical behaviors along the weld. Most research efforts have focused on the development of welding parameters to obtain sound welds, yet there is still an opportunity for performance improvement based on the under...

The unique combination of mechanical properties and the ability to be processed using injection molding techniques makes bulk metallic glasses (BMGs) excellent candidates for use in engnineering applications, especially in the medical device industry. Widespread use of BMGs is hindered by their inability to be joined to common engineering materials...

An open challenge on structural biomaterials is to obtain low-cost Ti-alloys with high elastic admissible strength (the ratio of yield strength to modulus). To reach this goal, we designed and characterized three quaternary alloys from the Ti-Nb-Fe system with additions of Zr and Sn. The samples were solution-treated and tested under two conditions...

During friction stir welding or processing (FSP), temperature and deformation have influence on the final microstructure and mechanical properties. Studying microstructures before and after welding might help interpreting mechanical and corrosion resistance; however, microstructural evolution during the process remains unknown. In this study, a FSP...

Coke drums are massive pressure vessels used in the oil and gas industry, which are subjected to demanding cyclic thermomechanical loading. Such conditions generate severe plastic deformation that leads to bulging and cracking during service due to low-cycle fatigue. The cracks are often repaired in programed maintenance shutdowns, and the repair p...

Quenching and partitioning (Q&P) and a novel combined process of hot straining (HS) and Q&P (HSQ&P) treatments have been applied to a TRIP-assisted steel in a Gleeble®3S50 thermomechanical simulator. The heat treatments involved intercritical annealing at 800 °C and a two-step Q&P heat treatment with a partitioning time of 100 seconds at 400 °C. Th...

The current work characterizes the microstructure and mechanical properties of two arc melted Co-Ni-based superalloys containing in atomic percent: 1) Co-40Ni-10Al-7.5W-10Cr-3Ta-0.06B-0.6 C and 2) Co-40Ni-10Al-7.5W-10Cr-3Nb-0.06B-0.6 C. These two materials named 3Ta and 3 Nb, respectively, were characterized by X-Ray diffraction analysis, different...

Evaluation was made of friction stir welded joints, identifying conditions that resulted in satisfactory welded joints free from defects and with microstructural characteristics that provided good mechanical properties. Microstructural characterization and cooling curve analysis of the joints with lower and higher heat inputs evidenced deformation...

This work details the development of a new cobalt-free stainless steel powder metallurgy hardfacing alloy designed to replace Stellite 6, a cobalt-based hardfacing alloy used in nuclear valve applications. The fundamental strategy centers on alloying stainless steels with up to 0.5 wt% nitrogen, which is shown to increase both the volume fraction o...

The objective of this work is the evaluation of hydrogen effects on the martensitic transformation and strain hardening in Duplex Stainless Steels (DSS) SAF 2205 (UNS S32205/S31803). DSS are two-phase alloys (austenite and ferrite), which are used for applications requiring high mechanical strength, in corrosive environments. Therefore, it is neces...

In this project, the extent of damage is evaluated by means of cavity mapping using confocal laser scanning microscopy, and the cavity neighborhoods are characterized through XEDS and EBSD mapping. A summary of the most common features and phases around cavities is reported. Comparison of cavity and inclusion distributions shows that inclusions are...

Controlling the amount of reverted austenite at room temperature allows for tailoring of mechanical properties in supermartensitic stainless steels. The austenite reversion and stabilization occurs during inter-critical tempering through partitioning of austenite-stabilizing elements. The degree of partitioning greatly depends on the reversion temp...

Duplex stainless steels are successful in a variety of applications such as the food industry, petrochemicals and plants for desalination of seawater, where high corrosion resistance and high mechanical strength are required. However, the beneficial microstructure may change during fusion welding steps, and it can compromise the performance of thes...

In this work we studied the phase transformations in a single pass welding joint of AA5083-H116 alloy using GMAW-P automated process, 80Ar19He1O2 shielding gas mixture, ER5183 filler metal and different heat inputs. The methodology included a preliminary analysis using optical microscopy, which identified morphological changes in microstructure of...

Correlative physical simulation, synchrotron x-ray diffraction and laser dilatometry were used to characterize the surface and volumetric austenite reversion kinetics and stability in a Ti-stabilized supermartensitic stainless steel. A fast heating rate of 500 °C s−1 was used to minimize any martensite to austenite reversion related to the heating...

Rapid Nanometer Mapping of Nickel-Steel Friction Stir Weld Joint - Volume 23 Issue S1 - Genevieve Lee, Guilherme Abreu-Faria, F Johnnatan Rodríguez, Jonathan Orsborn, Antonio J. Ramirez

2013 - 1st Proceedings of FSW -- Osaka -- Page 65 DOI: 10.1533/978-1-78242-164-1.75

Resumo Sabe-se que as velocidades de soldagem e rotacional, força axial, ângulo de inclinação e desenho da ferramenta são as principais variáveis de entrada independentes, que são utilizadas para controlar o processo de soldagem por atrito com pino não consumível, e que a taxa de geração de calor, taxa de resfriamento, força na direção de soldagem...

Dissimilar joining of advanced engineering alloys is fundamental for the development of new applications. However, joining two distinct materials poses difficulties owing to the several metallurgical and thermo-physical problems that can arise. This paper describes the work performed on dissimilar laser welding of NiTi and CuAlMn shape memory alloy...

Microstructure evolution during friction stir welding (FSW) of mild steel and Ni-based alloy 625 was studied. Regarding the Ni-based alloy, the welding process led to grain refinement caused by discontinuous and continuous dynamic recrystallization, where bulging of the pre-existing grains and subgrain rotation were the primary mechanisms of recrys...

The microstructure and mechanical properties of dissimilar butt-joints between a high-strength low alloyed (HSLA) grade and an austenitic high Mn TRIP steel were investigated. The tool rotation and the tool offset toward the TRIP steel were varied between 300–500 rpm and 1–2 mm, respectively. Tool advancing speed amounted to 100 mm/min. Maximum ten...

Duplex stainless steels are successfully used in a wide variety of applications in areas such as the food industry, petrochemical installations, and sea water desalination plants, where high corrosion resistance and high mechanical strength are required. However, during fusion welding operations, there can be changes to the favorable microstructure...

Friction stir welding with the optimum parameters offers high toughness and mechanical properties for pipeline steel applications; however, at subzero temperatures such joints have shown decreased toughness relative to room temperatures values as well as predominantly brittle behavior. This paper relates certain microstructural features to fracture...

Friction stir welding with the optimum parameters offers high toughness and mechanical properties for pipeline steel applications; however, at subzero temperatures such joints have shown decreased toughness relative to room temperatures values as well as predominantly brittle behavior. This paper relates certain microstructural features to fracture...

Trends in Welding Research, Proceedings of the 9th International Conference. Hot torsion physical simulation was used to reproduce the microstructure of the thermomechanically affected zone (TMAZ) of friction stir welded UNS S32205 duplex stainless steel. Such microstructure reproduction under controlled conditions allows the estimation of the ther...