ProgramMaster Logo
Conference Tools for 2020 AWS Professional Program
Login
Register as a New User
Help
Submit An Abstract
Propose A Symposium
Presenter/Author Tools
Organizer/Editor Tools
About this Abstract
Meeting 2020 AWS Professional Program
Symposium 2020 AWS Professional Program
Presentation Title Influence of Composition on the Solidification and Mechanical Properties of HP-modified Heat-resistant Austenitic Stainless Steels
Author(s) Sean M. Orzolek, John N DuPont
On-Site Speaker (Planned) Sean M. Orzolek
Abstract Scope Introduction Heat resistant austenitic stainless steels such as 0.4C-25Cr-35Ni-1Nb, HP-Nb alloys are commonly used in high temperature applications (>850°C) for applications such as ethylene pyrolysis tubes and furnace rolls. HP-Nb alloys exhibit high temperature corrosion resistance and good creep properties due to the high volume fractions of MC niobium carbides, as well as, M7C3 and M23C6 chromium carbides. However, these carbides can form a continuous network after casting or during service which leads to poor ductility and weldability. Previous studies have reported that HP-Nb alloys are susceptible to hot cracking in the Heat Affected Zone during fabrication following the pathway of the continuous carbide network along the grain boundaries and interdendritic regions. As the microstructure and concomitant carbide continuity is a result of the casting conditions and alloy composition, a thorough study is needed to explore the solidification of these alloys. Although the solidification of Ni-Nb-C and Ni-Cr-C ternary systems are well documented, there is limited information concerning the Ni-Cr-Nb-C quaternary system where both chromium and niobium carbides form. Therefore, the objective of this study is to improve the understanding of the solidification in the Ni-Cr-Nb-C quaternary system in order to understand the relation between composition, microstructure and mechanical properties of HP-Nb alloys. Experimental Procedures The solidification of HP alloys has been studied through the development of an alloy matrix with systematic variations of carbon, silicon, niobium, titanium and tungsten. Experimental alloys were prepared at the University of Alabama and poured into 45lb wedge shaped blocks for a total of 18 unique chemistries. Industrial centrifugally cast HP-Nb material was also included in the study in order to compare to the experimental alloy matrix for a total of 30 alloys. Samples were extracted from the center wedge or cast tubes and metallographically prepared to a final polish of 50nm colloidal silica. Differential thermal analysis (DTA) was conducted using a Netzsch STA 409 with 500mg ± 50mg samples and a heating and cooling rate of 10°C/min in order to determine the liquidus and eutectic transformation temperatures. Scanning electron microscopy (SEM) was conducted using a FEI Scios Dual Beam microscope with an accelerating voltage of 15kV and a beam current of 13nA using an electron backscatter detector. Backscatter electron images were processed via a quantitative image analysis program written in MATLAB to extract phase fractions of each constituent. Electron microprobe analysis (EPMA) was conducted using a Joel JXA-8900 with an accelerating voltage of 15kV and beam current of 30nA for phase identification and to determine the partition coefficients for representative alloys. Thermo-Calc Scheil solidification modeling was conducted using the TCNi9 database. Room temperature tensile testing was conducted in duplicate for each alloy according to ASTM E8. Weldability was assessed through longitudinal varestraint testing with a sample geometry of 6” x 1” x 0.25” and an imposed strain of five percent. Results and discussion Fractography of the room temperature tensile samples revealed that fracture consistently occurred through continuous carbide networks along dendritic boundaries. The mechanism of cracking in HP-Nb alloys was found to initiate with microcracking within the M7C3 carbides after which, the continuous carbide network provides a pathway for crack propagation. However, the cracking preferentially propagated through M7C3 carbides instead of MC carbides. Previous studies have conducted nanoindentation on each carbide where, a hardness of 14.5 ± 2.5 GPa was observed for the M7C3 carbides and 25.7 ± 3.6 GPa for the MC carbides. Because hardness and tensile strength are directly correlated, a lower hardness indicates a lower tensile strength and is therefore likely the reason why cracking initiated in the M7C3 carbides. Longitudinal varestraint tests revealed that cracking primarily occurred in the base metal and low temperature heat affected zones, associated with insufficient ductility to support the residual stresses from welding. Volume fraction data measured from the quantitative image analysis procedure was used in combination with EPMA compositional data to calculate the experimental eutectic points for the niobium and chromium eutectic carbides. These points were then plotted to represent the nickel rich corner of the Ni-Cr-Nb-C liquidus projection. Solidification modeling was then conducted assuming nonequilibrium conditions for chromium and niobium and equilibrium conditions for carbon and were plotted along with the experimental liquidus projection. From this, increasing the nominal concentration of niobium was found to increase the volume fraction of MC carbide and a decrease in the volume fraction of the M7C3 carbides and increasing the nominal concentration of carbon resulted in an increase in M7C3 carbides as well as total eutectic constituent. Conclusion Longitudinal varestraint testing and room temperature tensile tests were observed to have the same fracture mechanism which initiated in the chromium rich carbides and propagated through the continuous carbide network. Fracture was found to preferentially initiate within the chromium carbides instead of the MC carbides, associated to the lower hardness and therefore lower tensile strength. An experimental Ni-Cr-Nb-C liquidus projection was developed and revealed that the addition of niobium results in an increase in the volume fraction of MC carbide and a decrease in the volume fraction of the chromium carbide. The addition of carbon resulted in an increase of the eutectic constituent through a minor increase in the volume MC carbides and a significant increase in the volume fraction of chromium carbides. Statistical regression techniques reveal a correlation between increasing volume fraction of M7C3 carbides and decreasing ductility, where no correlation is observed with increasing volume fraction MC carbide. The results of this study show that high volume fractions of chromium carbide are detrimental to the room temperature ductility and therefore weldability of HP-Nb alloys.
Proceedings Inclusion? Definite: Other

OTHER PAPERS PLANNED FOR THIS SYMPOSIUM

101st Year of the American Welding Society: Changes in Welding & Outlook
Additive Manufacture of the First Concentric Reduction Sleeve Used in the Brazilian Oil and Gas Industry
Additive Manufacturing Using Semi-solids
Advances in Robotic Arc DED AM for Shipbuilding
Aluminum Root Pass Quality Using Rotating Electrode GMAW on Ceramic Abstract
An Efficient Part-scale Model to Predict Distortion on Overhang Structure in Laser Powder Bed Fusion Additive Manufacturing
An Overview of LME Cracking in Advanced High Strength Automotive Steels
Analysis of Dynamic Evolution of Weld Pool for the Real-time Monitoring of Penetration Using Deep Learning
Avoiding Tool Failure and Defects in Friction Stir Welding Using Machine Learning
Bondline Properties in High Frequency Welding of Steels
Building a Digital Twin for Welding Process Monitoring, Visualization and Control Based on Deep Learning
Characterization of the Fourth Generation of Nickel-Chromium Welding Products for Nuclear Service
Chipping Study of Friction Element Welding
Computational Modeling on Defect Formation during Self-reacting Friction Stir Welding
Copper Foil Welding for Battery Manufacturing
Correlating Laser Power and Microstructural Properties of Additively Manufactured Ti-6Al-4V Fabricated by Directed Energy Deposition
Creep Strength Variation in Simulated ICHAZs of Grade 91 Steel
Design of an Austenitic Steel Weldment System Using ICME
Development of Industry 4.0 Software for Arc-welding Energy Monitoring and Traceability
Development of Interlayer Technology to Join Advanced Materials for the Transportation Industry
Development, Optimization, and Mechanical Testing of ER80S-G Girth Welds on Internally Clad API 5L Grade X65 Pipes
Dissimilar Joining of Carbon Fiber Reinforced Composite to Magnesium Alloy by Friction Self-Piercing Riveting Process
Effect of Aluminum on Primary Carbides in Chromium Carbide Overlays
Effect of Chemical Composition of Welding Consumable on Slag Formation and Weld Corrosion Resistance
Effect of Heating Rate on Austenite Formation in a Low Carbon Microalloyed Steel
Effect of Phase Transformations on Mechanical Properties of Ti Free Grade 300 Maraging Steel Manufactured by Laser Powder Bed Fusion (LPBF)
Electron Beam Brazing of Stainless Steel Using NIORO Filler Metal
Evaluation of Braze Joints for Hydrogen Purification Diffuser
Failure Analysis: Evaluating a Low Strength Solder Joint
Fundamentals and Techniques for High-speed Imaging of Welding
High Deposition Gas Metal Arc Variants for Directed Energy Deposition Additive Manufacturing
High Efficient Modification of Arc Welding Processes via Modeling and Sensing Weld Pool Behaviors
High Penetration Buried Arc Gas Metal Arc Welding for Shipyard Steel Plate Fabrication
Hybrid Laser Welding on API 5L Pipeline Steels
Hyper-duplex Stainless Steel Intermetallic Precipitation Behavior during Cladding
Improper Weld Field Fabrication Caused Premature Failure
In-situ Measurement and Numerical Simulation for Linear Friction Welding of Complex Titanium Structures
In-situ Synchrotron Diffraction Measurement of Solidification Behavior during Laser Welding of Multi-principal-component Alloy
Induction Heating-assisted Friction Stir Welding in Low Carbon Steel Plates
Influence of Composition on the Solidification and Mechanical Properties of HP-modified Heat-resistant Austenitic Stainless Steels
Influence of Cooling Rate on Microstructure Formation in Rapid Solidification of Ni2MnGa Alloy
Influence of Hydrogen on the Softened HAZ in Various Carbon Steel Welds
Integrated Computational Materials Engineering (ICME) Techniques to Enable a Material-informed Digital Twin Prototype for Marine Structures
Integrated Modeling of Multi-process Automotive Lap Joining – Part 3: Microstructure and Mechanical Properties
Investigation of a Curly Toolpath in Friction Stir Welding
Investigation of Laves Phase Formation in Inconel 718 Fabricated by Laser Powder Bed Fusion
Investigation of Thermally Assisted Friction Element Welding
Joining Dissimilar Metals of DP590 Steel and AZ31B Magnesium Sheets by Ultrasonic Spot Welding
Low-cycle Fatigue Evaluations of Ni-steel Dissimilar Joints for Coke Drum Welding Repairs
Machine Learning for Automatic Recognition of Microstructures
Mechanical Properties Assessment of Carbon and Low-alloy Steel Parts Built by GMA-DED
Mechanistic Models and Machine Learning to Mitigate Common Defects in Metal Printing
Metallic Powder Core Tubular Wire Development for Additive Manufacturing
Microstructural and Mechanical Property Characterization of Reaction Synthesis Aluminum Metal Matrix Composites Produced by Additive Manufacturing
Microstructure and Mechanical Properties of Intercritical-treated Grade 91 Steel
Mitigation of Liquid Metal Embrittlement in Galvannealed AHSS Welds Using High Entropy Alloy Filler
Modal Analysis of Ultrasonic Welding to Enable Multi-spot Dissimilar Material Joining
Modeling and Comparing Human Welder’s Operation Between Stereo Camera and Virtual Reality
Modeling of In-situ Tempering of a Creep Resistant Ferritic Martensitic Steel during Multi-layer Additive Manufacturing
Modeling of Mash Seam Welding Using Improved Electro-thermo-mechanical Simulation
Modelling of Laser Cladding Using Gaussian Heat Source Profile and Verification with Experimental Results
Multi-scale and Multi-physics Modeling of Process-microstructure-property Relationship in Metal Additive Manufacturing
New Approaches in Friction Welding Advanced PM Nickel Base Superalloys
Numerical Study on Heat Transfer Mechanisms in Electric Arc Columns
Optimization of Tool Path and Microstructure in Large Scale Metal Additive Manufacturing with Multi-heat Sources
Phase Transformation Analysis and Microstructural Characterization of the Heat Affected Zone in Grade 92 Steel Welds
Process Control Using Predictive Equations for Zero Programming Laser Cladding Facility
Process, Microstructure and Fracture Mode of Magnesium to Steel Dissimilar Metal Spot Joints
Pulsed-arc Welding of Battery Tabs for Vehicle Electrification
PWHT of 347SS Weldments for Thermal Energy Storage Concentrating Solar Power Applications
Real-time Prediction of Weld Penetration from Dynamic Weld Pool-arc Images Deep Learning Based
Recent Developments in Metal Additive Manufacturing
Research and Development of a Novel TIG Welding Technology for Joining Thin Sheets Applying in Metal Forming Field
Residual Stress Measurement on High-strength Steel Panels for Shipbuilding Application
Resistance Spot Welding Challenges, Root Causes, and Suggested Welding Practices When Welding 3rd Generation AHSS
Role of Retained Austenite in Mechanical Response of Additively Manufactured 17-4 PH Stainless Steel
SMART Camera in the Welding Torch for Manual Welding Quality and Productivity
State-of-the-art of Underwater Wet Welding Practice
Strain Ageing of Inconel 740H and 347H
Suitability of Using Thin Wire in Wire Arc Additive Manufacturing (GMA-DED)
Sulfur Implantation in Alloy 690 for the Study of Ductility-dip Cracking
Surface Modification via Metal Deposition and Selective Alteration
Surface Treatment of 3-D Printing Parts
Temper Bead Welding
The Correlation of Hardness to Toughness and the Superior Low Temperature Impact Properties of Martensite in RPV Steels Applied to Temper Bead Qualification
The Role of Inclusions in Duplex Stainless Steels Produced Using Laser-based Directed Energy Deposition Additive Manufacturing
Universal Representation of Arc Shape and Arc Column Characteristics for DC Electric Arcs Burning in Argon and Helium
Variation in Microstructure and Properties in the Heat Affected and Fusion Zones of Low-density Fe-Mn-Al-C Steel Welds
Variations in Microstructure and Mechanical Properties with Solidification Mode in L-PBF 316L
Welding of FeMnAl High-manganese Lightweight Steel

Questions about ProgramMaster? Contact programming@programmaster.org