Wire Arc Additive Manufacturing (WAAM) is revolutionizing how we make metal components, especially when it comes to materials like 304L austenitic stainless steel—a popular choice in industries such as aerospace, automotive, and healthcare due to its durability and corrosion resistance. The research paper titled “Microstructural Characteristics and Properties of Wire Arc Additive Manufactured 304L Austenitic Stainless Steel Cylindrical Components by Different Arc Welding Processes” published by Dr Maheswar Dwivedy, Associate Professor, Department of Mechanical Engineering and his post-doctoral scholar Dr B Prasanna Nagasai explores this innovative manufacturing method in detail, focusing on how different welding techniques affect the end product.

Overall, this research indicates that WAAM, with its different welding techniques, can produce 304L stainless steel cylinders that potentially outperform those made by conventional forging, both in terms of material efficiency and mechanical properties. Such findings are significant as they point towards more sustainable and cost-effective manufacturing methods that do not sacrifice quality.

Abstract

Wire arc additive manufacturing (WAAM) is an advanced additive manufacturing (AM) technology that offers low cost and high deposition rates, making it suitable for building large metal parts for structural engineering applications. However, various welding procedures result in differing heat inputs and repetitive heating treatments throughout the deposition process, which can affect the microstructural and mechanical characteristics of the parts. In the current study, cylindrical parts made of 304L austenitic stainless steel (ASS) were manufactured using the WAAM technique, employing both gas metal arc welding (GMAW) and cold metal transfer (CMT) processes. This study explores the correlation between WAAM techniques and their effects on the bead geometry, microstructure and mechanical properties. The paper presents detailed analyses of the microstructure using techniques such as optical microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The research findings suggest that the choice of arc welding process significantly affects the grain size, phase distribution, and defect formation within the 304L stainless steel, thereby influencing the mechanical properties and overall performance of the manufactured components. The WAAM-processed 304L ASS cylinders showed better performance compared to those manufactured using traditional industrial forging standards, indicating that WAAM-processed 304L ASS cylinders are suitable for industrial applications. This comprehensive evaluation provides insights into optimising welding processes for enhanced quality and performance of stainless steel cylindrical parts.

Highlights of the research

• Controlling heterogeneous microstructures in WAAM-processed 304L stainless steel is challenging.
• GMAW vs. CMT impacts on 304L ASS microstructure analysed.
• The upward growth of coarse austenite/ferrite morphologies is controlled by the wire retraction mechanism.
• CMT produced finer dendrites and more ferrite morphologies.
• WAAM 304L ASS components outperformed the wrought 304L ASS and forged 304L ASS.

Practical implementation/Social implications of the research

The practical implementation of Wire Arc Additive Manufacturing (WAAM) for 304L austenitic stainless steel could revolutionise multiple industries, including aerospace, automotive, medical devices, maritime, and energy, by allowing the production of complex, custom, and durable components with greater efficiency and reduced material waste. This shift not only promises economic benefits like cost reduction and job creation in advanced manufacturing sectors but also carries significant environmental advantages by minimising waste and the carbon footprint associated with traditional manufacturing processes. Furthermore, the technology enhances supply chain resilience by enabling local, on-demand production, which could be crucial during global disruptions. Socially, WAAM could increase access to customised medical aids in low-income regions, fostering greater equality. The adoption of WAAM thus holds the potential to impact manufacturing practices profoundly, driving innovation, sustainability, and inclusivity across various sectors.

Collaborations

Dr V Balasubramanian, Professor & Director, Centre for Materials Joining & Research (CEMAJOR), Annamalai University, Tamilnadu.

In the future, the research team plan to focus on developing Functionally Graded Materials (FGMs) of nickel and stainless steel using Wire Arc Additive Manufacturing (WAAM). This research will aim to leverage the unique properties of each metal to create components with tailored functional performance for demanding applications. Key challenges will include optimising material interfaces, controlling deposition processes, and ensuring structural integrity.

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The Department of Mechanical Engineering at SRM University-AP is proud to present its research paper titled, Study on Properties and Microstructure of Wire Arc Additive Manufactured 2209 Duplex Stainless Steel by Dr Maheshwar Dwivedy and post-doctoral researcher, Dr B Prasanna Nagasai. Below is a brief write-up on their research.

Abstract:

This study investigates the properties and microstructure of 2209 duplex stainless steel (DSS) components fabricated using the wire arc additive manufacturing (WAAM) technique, specifically employing the gas metal arc welding (GMAW) process. The research focuses on the mechanical properties and microstructural characteristics of the produced cylindrical components. Detailed examination revealed that the microstructure varied from the bottom (region ①) to the top (region ②) of the cylinders, with hardness measurements ranging from 301 HV0.5 to 327 HV0.5, and impact toughness values from 118J to 154J. The tensile properties exhibited anisotropic behavior, with ultimate tensile strength and yield strength ranging from 750 to 790 MPa and 566 to 594 MPa, respectively. The study highlights the significant influence of complex heat cycles and cooling rates on the primary phase balance, resulting in a 50/50 austenite/ferrite distribution. Additionally, σ-phase precipitation was observed at the ferrite grain boundaries. The observed increase in austenite content from region ① to region ② is attributed to reduced cooling rates and extended time for solid-state phase transformation. This research provides valuable insights into optimizing the WAAM process for enhanced performance of 2209 DSS components.

Citation Format:

Prasanna Nagasai, B, Maheshwar Dwivedy, Malarvizhi, S. et al. Study on Properties and Microstructure of Wire Arc Additive Manufactured 2209 Duplex Stainless Steel. Metallogr. Microstruct. Anal. (2024). https://doi.org/10.1007/s13632-024-01089-8

Practical implementation:

The practical implementation of this research on Wire Arc Additive Manufacturing (WAAM) for Duplex Stainless Steel (DSS) has significant implications for industries requiring high-strength, corrosion-resistant components, such as construction, marine, and chemical processing. By optimizing the WAAM process to produce DSS parts with balanced microstructures, manufacturers can create durable and efficient parts more cost-effectively and with less material waste than traditional methods. This advancement could lead to more sustainable manufacturing practices, reducing the environmental impact and operational costs associated with producing large metal components. Socially, the widespread adoption of this technology could drive innovation, create new job opportunities in advanced manufacturing, and contribute to the development of stronger, longer-lasting infrastructure and machinery, ultimately benefiting the economy and society at large.

Collaborations:

Dr V Balasubramanian,
Professor & Director,
Centre for Materials Joining & Research (CEMAJOR)
Annamalai University, Annamalai Nagar-608002, Tamilnadu.

Dr P Snehalatha,
Associate Professor & Head
Department of Mechanical Engineering,
Sri Padmavathi Mahila Visvavidyalam, Tirupati, Andhra Pradesh-517502, India.

Future Research Plans:

In our upcoming work, we will focus on developing Functionally Graded Materials (FGMs) using Wire Arc Additive Manufacturing (WAAM), combining nickel and stainless steel. This research aims to harness the unique properties of each metal to create components tailored for specialized applications requiring high performance. Key challenges include optimizing material interfaces, refining deposition processes, and ensuring robust structural integrity throughout production.

The link to the article– https://doi.org/10.1007/s13632-024-01089-8

In a remarkable achievement, Dr Maheshwar Dwivedy, Associate Professor in the Department of Mechanical Engineering, has made a significant contribution to the field of materials science with his latest publication. The paper, entitled “Understanding heterogeneity and anisotropy of duplex stainless steel elastic/plastic nature through property mapping technique,” has been published in the esteemed journal Materials Letters, which boasts an impact factor of 3.0.

Dr Dwivedy’s research provides insightful analysis of the complex behaviours of duplex stainless steel, a material known for its high strength and corrosion resistance. By employing a property mapping technique, the study reveals the intrinsic heterogeneity and anisotropy of the material’s elastic and plastic properties. This groundbreaking work not only advances the understanding of duplex stainless steels but also opens up new possibilities for their application in various industries.
The publication of this paper in a journal with a significant impact factor is a testament to the quality and importance of the research conducted by Dr Dwivedy and his team. It underscores SRM University – AP’s commitment to fostering cutting-edge research and innovation.

Abstract
Accelerated property mapping, an advanced indentation technique, was used to describe the nanomechanical behaviour of duplex stainless steel (DSS) surfaces prior to and post-heat treatments. Heterogeneity in deformation responses and relative elastic and/or plastic nature of DSS was assessed on longitudinal and transverse directions through load-displacement curves, property maps, histograms of hardness (H), modulus (E) and indentation works. Empirical ratios such as H/E, (H/E)1/2, H3/E2 and plasticity index were employed to understand the anisotropy across the directions. It is crucial that for structural designing, heterogeneity and anisotropy of mechanical behaviour need to be accounted for improved property–optimisation.

Explanation of the Research in Layperson’s Terms

Duplex stainless steel (DSS), a unique category of steel, contains almost equal amounts of ferrite and austenite phases within its microstructure. These are employed in applications like boilers, pressure vessels, heat exchangers, etc., as they offer superior strength, ductility, toughness, and corrosion resistance properties compared to other steels. Mechanical characteristics of DSS are significantly influenced by manufacturing protocols including heat treatments. It is believed that anisotropy and heterogeneity in mechanical behaviour can be driven by microstructures post-material processing.

A comprehensive understanding of DSS material behaviour at the macroscopic scale is not feasible without knowledge of its features and their properties locally. Although the mechanical properties of DSS have been widely explored from a macroscopic perspective as well as innovative nano-scale property mapping techniques, the number of studies addressing anisotropy seen through small-scale characterization is rather restricted. In general, the preliminary assessment of the mechanical behaviour commonly done through hardness (H) and modulus (E) properties. For estimating the elasticity and/or plasticity of material or any surface, different empirical ratios were adopted namely H/E, H3/E2 and (H/E)1/2.

Practical Implementation or the Social Implications Associated
• This study demonstrates the notable differences in mechanical properties in longitudinal and transverse directions along with heterogeneity before and after heat treatments.
• It is felt crucial that for structural designing, heterogeneity and anisotropy of mechanical behaviour need to be accounted for improved property-optimisation.

Link to the article

Yet another groundbreaking achievement for the researchers at SRM University-AP! Prof. Ranjit Thapa, Dean-Research and Professor, Department of Physics, Prof. G S Vinod Kumar, Professor and Head, Department of Mechanical Engineering and Ms Harsha K, PhD scholar, continue to make their mark in the university’s excellent research legacy by having their patent “Tarnish Resistant Silver Composition and a Process for its Preparation” being granted by the Indian Patent Office. This innovative research team has used density functional theory to explain the tarnishing of silver. Their work also focuses on finding alloying elements that protect silver.

Abstract

The research is on the development of tarnish-resistant silver alloys from an experimental and computational perspective. With time, silver atoms on the surface of the metal undergo sulphidation and form Ag2S molecules. These particles will accumulate to form a layer whose thickness goes beyond 10nm, and then the human eye will start to find a discolouration on the surface of silver, which is tarnish. The stain colour changes from light yellow to dark brown. This reduces the lustre of silver and makes them aesthetically non-pleasing. The silver jewellery and articles manufacturing industry suffers from this tarnishing as it leads to the loss of material and money and ruins intricate designs made of silver. The research study attempts the problem by alloying silver with appropriate elements, which are computationally checked and verified. The team works with alloying elements such as Cu, Zn, Ge, Ti, Zr, Mg, Al, and Be. Along with tarnish resistance, the proposed alloys maintain high reflectance, good hardness, and excellent workability when spinning.

Figure.1 The images of different silver alloys after accelerated tarnish test in as-cast condition (first row) and after undergoing passivation heat treatment at 450°C for 1 hour in the presence of oxygen (second row).

Practical implementation/social implications of the research

• Stainless silver is in demand as customers want their precious metal articles to be kept for a longer time as heirlooms. So, the product that we could develop out of our composition will be making more demand for silver.
• It can increase the market potential of silver.
• It can lead to more innovations in the jewellery industry.

Collaborations

• Waman Hari Pethe
• Ashlyn Chemmannur
• TITAN

The team would continue to work on the scope of research to develop more tarnish-resistant compositions, improve the tensile strength, scratch resistance, surface hardness, and workability of silver alloys and find novel elements which can add to desirable properties of silver.

Figure.2 Reflectance of alloys (a) before tarnish test (b) after tarnish test

In a significant advancement in the field of material engineering, Dr Supen Kumar Sah, an esteemed Assistant Professor from the Department of Mechanical Engineering, has published a groundbreaking research paper.

The study, titled “Effect of Bi-Directional Material Gradation on Thermo-Mechanical Bending Response of Metal Ceramic FGM Sandwich Plates Using Inverse Trigonometric Shear Deformation Theory,” appears in the prestigious International Journal of Structural Integrity.

Dr Sah’s research provides new insights into the behaviour of Functionally Graded Materials (FGMs) under thermal and mechanical loads, which is crucial for the design of advanced engineering structures. His work employs an innovative inverse trigonometric shear deformation theory to analyse the bending response of metal-ceramic FGM sandwich plates, offering a more accurate prediction of their performance in real-world applications.

This publication not only highlights the cutting-edge research being conducted at SRM University but also positions Dr Sah as a leading figure in the application of FGMs in structural engineering. The findings from this paper have the potential to influence the design and optimization of materials used in various industries, from aerospace to automotive.

Abstract

The purpose of this study is to investigate the bending analysis of metal (Ti-6Al-4V) ceramic (ZrO_2) functionally graded material (FGM) sandwich plate having material property gradation along length and thickness direction under thermo-mechanical loading using inverse trigonometric shear deformation theory (ITSDT). Mechanical and thermal properties of BDFGM sandwich plates are considered temperature-dependent in the present study. Analytical solution for bending analysis of FGM plate has been carried out using Hamilton’s principle and Navier’s solution.

The present study shows that centre deflection, normal stress, and shear stress are significantly influenced by temperature-dependent material properties, bi-directional gradation exponents’ geometrical parameters, sandwich plate layer thickness, etc.

Title of the Research Paper in the Citation Format

Sah, S. K., Ghosh, A. (2024). Effect of Bi-Directional Material Gradation on Thermo-Mechanical Bending Response of Metal Ceramic FGM Sandwich Plates Using Inverse Trigonometric Shear Deformation Theory. International Journal Structural Integrity. DOI: 10.1108/IJSI-02-2024-0016

Collaborations

Prof Anup Ghosh, Indian Institute of Technology Kharagpur, India

Future Research Plans

Modelling and Analysis of porous uni and multi-directional Functionally Graded Material (FGM) plates to obtain the impact of porosity distributions over structural responses.

Analytical & Finite Element Solution for static and dynamic response of FGM sandwich plates employing non-polynomial shear deformation theories under elastic foundation.