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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Materials Simulation and Design".

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 32614

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Prof. Dr. Dariusz Fydrych

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Guest Editor

Faculty of Mechanical Engineering, Gdańsk University of Technology, G. Narutowicza 11/12, 80-233 Gdańsk, Poland
Interests: underwater welding; mechanics of materials; testing of welded joints
Special Issues, Collections and Topics in MDPI journals

Dr. Jacek Tomków

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Guest Editor

Division of Welding Engineering, Institute of Manufacturing and Materials Technology, Faculty of Mechanical Engineering and Ship Technology, Gdańsk University of Technology, G. Narutowicza 11/12, 80-233 Gdańsk, Poland
Interests: offshore constructions; offshore steels; underwater welding; welding; joining processes; materials engineering; friction stir welding; non-destructive testing; metals; weldability of metals; surfacing; thermal spraying; hydrogen embrittlement; cold cracking; diffusible hydrogen; high strength steel; coatings; materials science; failures
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Special Issue Information

Dear Colleagues,

Technological processes implemented in the water environment include the manufacturing and processing of engineering materials and giving them specific properties. The first group consists of processes carried out underwater out of necessity, when there is no technical possibility to lift the structural elements above the water surface or it is economically unjustified. In this case, water is an environment that generates serious technological and metallurgical problems (structural changes, cracking, porosity, stress, deformation). These processes include, for example, welding (arc, laser, adhesive bonding), cutting and coating, surfacing, and thermal spraying. On the other hand, the physicochemical properties of water can be attractive and used, e.g., to promote specific properties of materials. Typical processes that use water in this way are, e.g., friction stir welding, plasma cutting, laser remelting. The practical application of underwater technologies inextricably requires the development of techniques for testing the quality of processed materials and advanced automated and robotic applications, which enable operations in difficult conditions, e.g., at great depths or in conditions harmful to health.

Since the demand for materials and technologies, including design and control of mechanized and robotic systems used in the water environment, is still increasing significantly, experimental and simulation studies are an important factor contributing to their wider use.

The purpose of this Special Issue is to present the latest developments in the field of processing of materials in a water environment, especially in offshore and nuclear plant structures. This includes technologies of manufacturing, properties, degradation, failures, protection, maintenance and repairs, joining, and cutting of materials. The scope of this Special Issue mainly covers issues focused on assessing the influence of the environment and technology on the behavior of materials underwater and in other similar environments. We would like to invite scientists and industrial engineers to submit original research articles and reviews related to any of the topics mentioned above. The deadline for manuscript submissions is 31 December 2021.

The Special Issue will cover but not be limited to the following topics:

Coatings and films used as protection for offshore and nuclear plant structures;
Degradation and failures of offshore and nuclear plant materials;
Hydrogen embrittlement;
Underwater repair processes;
Underwater welding (wet welding, local dry cavity welding; dry hyperbaric and isobaric welding);
Underwater adhesive bonding,
Underwater cutting;
Underwater friction stir welding;
Underwater explosion welding;
Underwater surfacing;
Underwater laser treatment;
Underwater welding arc stability;
Underwater nondestructive inspection and testing;
Modeling and simulations of underwater joining and cutting processes;
Design and control of mechanized and robotic systems for underwater processes.

Prof. Dr. Dariusz Fydrych
Dr. Jacek Tomków
Guest Editors

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Keywords

underwater processing
underwater welding
wet welding
dry welding
local dry cavity welding
underwater cutting
underwater surfacing
welding arc stability
welding thermal cycle
welding metallurgy
thermal spraying
hydrogen embrittlement
cold cracking, corrosion
fatigue
wear
nondestructive testing
underwater robot control
modeling and simulation

Published Papers (12 papers)

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Editorial

Jump to: Research

4 pages, 212 KiB

Open AccessEditorial

Underwater Processing of Materials

by Dariusz Fydrych and Jacek Tomków

Materials 2022, 15(14), 4902; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15144902 - 14 Jul 2022

Cited by 2 | Viewed by 1027

Abstract

Technological processes carried out in the water environment include the production and processing of engineering materials and giving them specific properties [...] Full article

(This article belongs to the Special Issue Underwater Processing of Materials)

Research

Jump to: Editorial

14 pages, 6682 KiB

Open AccessArticle

Induction Heating in Underwater Wet Welding—Thermal Input, Microstructure and Diffusible Hydrogen Content

by Oliver Brätz, Jan Klett, Thomas Wolf, Knuth-Michael Henkel, Hans Jürgen Maier and Thomas Hassel

Materials 2022, 15(4), 1417; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15041417 - 14 Feb 2022

Cited by 14 | Viewed by 2191

Abstract

Hydrogen-assisted cracking is a major challenge in underwater wet welding of high-strength steels with a carbon equivalent larger than 0.4 wt%. In dry welding processes, post-weld heat treatment can reduce the hardness in the heat-affected zone while simultaneously lowering the diffusible hydrogen concentration in the weldment. However, common heat treatments known from atmospheric welding under dry conditions are non-applicable in the wet environment. Induction heating could make a difference since the heat is generated directly in the workpiece. In the present study, the thermal input by using a commercial induction heating system under water was characterized first. Then, the effect of an additional induction heating was examined with respect to the resulting microstructure of weldments on structural steels with different strength and composition. Moreover, the diffusible hydrogen content in weld metal was analyzed by the carrier gas hot extraction method. Post-weld induction heating could reduce the diffusible hydrogen content by −34% in 30 m simulated water depth. Full article

(This article belongs to the Special Issue Underwater Processing of Materials)

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19 pages, 3541 KiB

Open AccessArticle

An Experimental Study of Damage Detection on Typical Joints of Jackets Platform Based on Electro-Mechanical Impedance Technique

by Liaqat Ali, Sikandar Khan, Naveed Iqbal, Salem Bashmal, Hamad Hameed and Yong Bai

Materials 2021, 14(23), 7168; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14237168 - 25 Nov 2021

Cited by 9 | Viewed by 1450

Abstract

Many methods have been used in the past two decades to detect crack damage in steel joints of the offshore structures, but the electromechanical impedance (EMI) method is a comparatively recent non-destructive method that can be used for quality monitoring of the weld in structural steel joints. The EMI method ensures the direct assessment, analysis and particularly the recognition of structural dynamics by acquiring its EM admittance signatures. This research paper first briefly introduces the theoretical background of the EMI method, followed by carrying out the experimental work in which damage in the form of a crack is simulated by using an impedance analyser at different distances. The EMI technique is used to identify the existence of damage in the welded steel joints of offshore steel jacket structures, and Q345B steel was chosen as the material for test in the present study. Sub-millimetre cracks were found in four typical welded steel joints on the jacket platform under circulating loads, and root average variance was used to assess the extent of the crack damage. Full article

(This article belongs to the Special Issue Underwater Processing of Materials)

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25 pages, 9092 KiB

Open AccessArticle

Study on Microstructural Characterization, Mechanical Properties and Residual Stress of GTAW Dissimilar Joints of P91 and P22 Steels

by Anupam Sauraw, Atul Kumar Sharma, Dariusz Fydrych, Sachin Sirohi, Ankur Gupta, Aleksandra Świerczyńska, Chandan Pandey and Grzegorz Rogalski

Materials 2021, 14(21), 6591; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14216591 - 02 Nov 2021

Cited by 43 | Viewed by 3716

Abstract

This article deals with the dissimilar joining of two different grade Cr-Mo steel (2.25Cr-1Mo: P22 and modified 9Cr-1Mo: P91) for power plant application. The dissimilar butt-welded joint was produced for conventional V groove design by using the gas tungsten arc welding (GTAW) process with the application of an ERNiCrMo-3 Ni-based super alloy filler. A microstructure characterization was performed to measure the inhomogeneity in the microstructure and element diffusion across the interface in a welded joint. The experiments were also performed to evaluate the mechanical properties of the dissimilar welded joint in as-welded (AW) and post-weld heat treatment (PWHT) conditions. An acceptable level of the mechanical properties was obtained for the AW joint. After PWHT, a significant level of the element diffusion across the interface of the weld metal and P22 steel was observed, resulting in heterogeneity in microstructure near the interface, which was also supported by the hardness variation. Inhomogeneity in mechanical properties (impact strength and hardness) was measured across the weldments for the AW joint and was reduced after the PWHT. The tensile test results indicate an acceptable level of tensile properties for the welded joint in both AW and PWHT conditions and failure was noticed in the weak region of the P22 steel instead of the weld metal. Full article

(This article belongs to the Special Issue Underwater Processing of Materials)

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24 pages, 21479 KiB

Open AccessArticle

Study on Microstructure and Mechanical Properties of Laser Welded Dissimilar Joint of P91 Steel and INCOLOY 800HT Nickel Alloy

by Vishwa Bhanu, Dariusz Fydrych, Ankur Gupta and Chandan Pandey

Materials 2021, 14(19), 5876; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14195876 - 07 Oct 2021

Cited by 25 | Viewed by 2793

Abstract

This investigation attempts to explore the weld characteristics of a laser welded dissimilar joint of ferritic/martensitic 9Cr-1Mo-V-Nb (P91) steel and Incoloy 800HT austenitic nickel alloy. This dissimilar joint is essential in power generating nuclear and thermal plants operating at 600–650 °C. In such critical operating conditions, it is essential for a dissimilar joint to preserve its characteristics and be free from any kind of defect. The difference between the physical properties of P91 and Incoloy 800HT makes their weldability challenging. Thus, the need for detailed characterization of this dissimilar weld arises. The present work intends to explore the usage of an unconventional welding process (i.e., laser beam welding) and its effect on the joint’s characteristics. The single-pass laser welding technique was employed to obtain maximum penetration through the keyhole mode. The welded joint morphology and mechanical properties were studied in as-welded (AW) and post-weld heat treatment (PWHT) conditions. The macro-optical examination shows the complete penetrations with no inclusion and porosities in the weld. The microstructural study was done in order to observe the precipitation and segregation of elements in dendritic and interface regions. Solidification cracks were observed in the weld fusion zone, confirming the susceptibility of Incoloy 800HT to such cracks due to a mismatch between the melting point and thermal conductivity of the base metals. Failure from base metal was observed in tensile test results of standard AW specimen with a yield stress of 265 MPa, and after PWHT, the value increased to 297 MPa. The peak hardness of 391 HV was observed in the P91 coarse grain heat-affected zone (CGHAZ), and PWHT confirmed the reduction in hardness. The impact toughness results that were obtained were inadequate, as the maximum value of impact toughness was obtained for AW P91 heat-affected zone (HAZ) 108 J and the minimum for PWHT Incoloy 800HT HAZ 45 J. Thus, difficulty in obtaining a dissimilar joint with Incoloy 800HT using the laser beam welding technique was observed due to its susceptibility to solidification cracking. Full article

(This article belongs to the Special Issue Underwater Processing of Materials)

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19 pages, 8760 KiB

Open AccessArticle

Metallurgy and Mechanism of Underwater Wet Cutting Using Oxidizing and Exothermic Flux-Cored Wires

by Sergey G. Parshin, Alexey M. Levchenko and Pengfei Wang

Materials 2021, 14(16), 4655; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14164655 - 18 Aug 2021

Cited by 4 | Viewed by 1976

Abstract

This paper considers the metallurgical processes of dissociation, ionization, oxidation, deoxidation, and dissolution of oxides during underwater wet cutting. A multiphase mechanism of underwater wet cutting consisting of working and idle cycles of the electrical process in a pulsating vapor gas bubble is proposed. A model of arc penetration into metal due to metal oxidation and stabilization of the arc by the inner walls of a narrow kerf is proposed. For underwater cutting of 10 KhSND, 304L steel, CuAl5, and AlMg4.5Mn0.7 alloy, we provide a principle of modeling the phase composition of the gas mixture based on high oxygen concentration, improving ionization, enthalpy, heat capacity, and thermal conductivity of plasma through the use of a mixture of KNO₃, FeCO₃ and aluminum. The method of improving the thermophysical properties and ionization of plasma due to the exothermic effect when introducing Fe₃O₄, MoO₂, WO₂ oxides and Al, Mg, Ti deoxidizers is proposed. Although a negative effect of refractory slag was revealed, it could be removed by using the method of reducing surface tension through the ionic dissolution of refractory oxides in Na₃AlF₆ cryolite. In underwater cutting of 10 KhSND and 304L, the steel welding current was 344–402 A with a voltage of 36–39 V; in cutting of CuAl5 and AlMg4.5Mn0.7 alloy, the welding current was 360–406; 240 A, with a voltage of 35–37; 38 V, respectively, with the optimal composition of flux-cored wire: 50–60% FeCO₃ and KNO₃, 20–30% aluminum, 20% Na₃AlF₆. Application of flux-cored wires of the KNO₃-FeCO₃-Na₃AlF₆-Al system allowed stable cutting of 10KhSND, AISI 304L steels, and CuAl5 bronze with kerf width up to 2.5–4.7 mm. Full article

(This article belongs to the Special Issue Underwater Processing of Materials)

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14 pages, 5053 KiB

Open AccessArticle

Weldability of Underwater Wet-Welded HSLA Steel: Effects of Electrode Hydrophobic Coatings

by Jacek Tomków

Materials 2021, 14(6), 1364; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14061364 - 11 Mar 2021

Cited by 21 | Viewed by 2458

Abstract

The paper presents the effects of waterproof coatings use to cover electrodes on the weldability of high-strength, low-alloy (HSLA) steel in water. With the aim of improving the weldability of S460N HSLA steel in water, modifications of welding filler material were chosen. The surfaces of electrodes were covered by different hydrophobic substances. The aim of the controlled thermal severity (CTS) test was to check the influence of these substances on the HSLA steel weldability in the wet welding conditions. The visual test, metallographic tests, and hardness Vickers HV10 measurements were performed during investigations. The results proved that hydrophobic coatings can reduce the hardness of welded joints in the heat-affected zone by 40–50 HV10. Additionally, the number of cold cracks can be significantly reduced by application of waterproof coatings on the filler material. The obtained results showed that electrode hydrophobic coatings can be used to improve the weldability of HSLA steel in underwater conditions. Full article

(This article belongs to the Special Issue Underwater Processing of Materials)

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21 pages, 10902 KiB

Open AccessArticle

Underwater Local Cavity Welding of S460N Steel

by Jacek Tomków, Anna Janeczek, Grzegorz Rogalski and Adrian Wolski

Materials 2020, 13(23), 5535; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13235535 - 04 Dec 2020

Cited by 28 | Viewed by 3579

Abstract

In this paper, a comparison of the mechanical properties of high-strength low-alloy S460N steel welded joints is presented. The welded joints were made by the gas metal arc welding (GMAW) process in the air environment and water, by the local cavity welding method. Welded joints were tested following the EN ISO 15614-1:2017 standard. After welding, the non-destructive—visual, penetrant, radiographic, and ultrasonic (phased array) tests were performed. In the next step, the destructive tests, as static tensile-, bending-, impact- metallographic (macroscopic and microscopic) tests, and Vickers HV10 measurements were made. The influence of weld porosity on the mechanical properties of the tested joints was also assessed. The performed tests showed that the tensile strength of the joints manufactured in water (567 MPa) could be similar to the air welded joint (570 MPa). The standard deviations from the measurements were—47 MPa in water and 33 MPa in the air. However, it was also stated that in the case of a complex state of stress, for example, bending, torsional and tensile stresses, the welding imperfections (e.g., pores) significantly decrease the properties of the welded joint. In areas characterized by porosity the tensile strength decreased to 503 MPa. Significant differences were observed for bending tests. During the bending of the underwater welded joint, a smaller bending angle broke the specimen than was the case during the air welded joint bending. Also, the toughness and hardness of joints obtained in both environments were different. The minimum toughness for specimens welded in water was 49 J (in the area characterized by high porosity) and in the air it was 125 J (with a standard deviation of 23 J). The hardness in the heat-affected zone (HAZ) for the underwater joint in the non-tempered area was above 400 HV10 (with a standard deviation of 37 HV10) and for the air joint below 300 HV10 (with a standard deviation of 17 HV10). The performed investigations showed the behavior of S460N steel, which is characterized by a high value of carbon equivalent (CeIIW) 0.464%, during local cavity welding. Full article

(This article belongs to the Special Issue Underwater Processing of Materials)

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17 pages, 5042 KiB

Open AccessArticle

The Effect of Polarity and Hydrostatic Pressure on Operational Characteristics of Rutile Electrode in Underwater Welding

by Andrés M. Moreno-Uribe, Alexandre Q. Bracarense and Ezequiel C. P. Pessoa

Materials 2020, 13(21), 5001; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13215001 - 06 Nov 2020

Cited by 17 | Viewed by 2628

Abstract

In order to provide a better understanding of the phenomena that define the weld bead penetration and melting rate of consumables in underwater welding, welds were developed with a rutile electrode in air welding conditions and at the simulated depths of 5 and 10 m with the use of a hyperbaric chamber and a gravity feeding system. In this way, voltage and current signals were acquired. Data processing involved the welding voltage, determination of the sum of the anodic and cathodic drops, calculation of the short-circuit factor, and determination of the melting rate. Cross-sectional samples were also taken from the weld bead to assess bead geometry. As a result, the collected data show that the generation of energy in the arc–electrode connection in direct polarity (direct current electrode negative-DCEN) is affected by the hydrostatic pressure, causing a loss of fusion efficiency, a drop of operating voltage, decreased arc length, and increased number of short-circuit events. The combination of these characteristics kept the weld bead geometry unchanged, compared to dry weld conditions. With the positive electrode (direct current electrode positive-DCEP), radial losses were derived from greater arc lengths resulting from increasing hydrostatic pressure, which led to a decrease in weld penetration. Full article

(This article belongs to the Special Issue Underwater Processing of Materials)

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17 pages, 23503 KiB

Open AccessArticle

Plasticity of Bead-on-Plate Welds Made with the Use of Stored Flux-Cored Wires for Offshore Applications

by Aleksandra Świerczyńska and Michał Landowski

Materials 2020, 13(17), 3888; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13173888 - 03 Sep 2020

Cited by 27 | Viewed by 2666

Abstract

Extreme atmospheric conditions in the marine and offshore industry are harmful to engineering materials, especially to welded joints, and may cause degradation of their properties. This article presents the results of research on the plasticity of bead-on-plate welds made using two types of seamless, copper plated flux-cored wires. Before welding, spools with wire were stored for 1 month in two distinct locations with different geographical and industrial conditions in Poland, and then subjected to visual examination. Bead-on-plate welds were subjected to a static tensile test and on this basis plasticity indexes showing the effect of storage on plasticity were determined. The fractures after tensile tests and the surfaces of the wires were examined on an electron scanning microscope. Additionally, diffusible hydrogen content in deposited metal measurements for each condition were carried out. The highest degradation level was found for wire stored in an agricultural building in north-eastern Poland—there was an almost fourfold decrease in the plasticity index value and the highest diffusible hydrogen content. For the same wire and the same location, the largest difference was also observed in fracture morphology after the tensile test—ductile fracture was obtained for wire at delivery condition while an almost full cleavage fracture was found after relatively short (1 month) storage of wire. Full article

(This article belongs to the Special Issue Underwater Processing of Materials)

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18 pages, 4797 KiB

Open AccessArticle

The Applicability of the Standard DIN EN ISO 3690 for the Analysis of Diffusible Hydrogen Content in Underwater Wet Welding

by Jan Klett, Thomas Wolf, Hans Jürgen Maier and Thomas Hassel

Materials 2020, 13(17), 3750; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13173750 - 25 Aug 2020

Cited by 15 | Viewed by 2532

Abstract

The European standard ISO 3690 regulates the measurement of diffusible hydrogen in arc-welded metal. It was designed for different welding methods performed in dry atmosphere (20% humidity). Some details of the standard are not applicable for wet underwater welding. The objective of this study was to extend the applicability of DIN EN ISO 3690:2018-12 to underwater wet-shielded metal arc welding (SMAW). Four different aspects regulated within the standard were accounted for: (1) sample dimensions and number of samples taken simultaneously; (2) time limitations defined by the standard regarding the welding and the cleaning process; (3) time, temperature, and method defined for analysis of the diffusible hydrogen content; (4) normalization of the hydrogen concentration measured. Underwater wet welding was performed using an automated, arc voltage-controlled welding machine. The results are discussed in light of standard DIN EN ISO 3690, and recommendations are provided for the analysis of diffusible hydrogen content upon underwater wet welding. Full article

(This article belongs to the Special Issue Underwater Processing of Materials)

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15 pages, 7232 KiB

Open AccessArticle

Effect of Electrode Waterproof Coating on Quality of Underwater Wet Welded Joints

by Jacek Tomków, Dariusz Fydrych and Kamil Wilk

Materials 2020, 13(13), 2947; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13132947 - 01 Jul 2020

Cited by 35 | Viewed by 3775

Abstract

In this paper, the effects of different hydrophobic coatings on the surface of covered electrodes on the quality of wet welded carbon steel joints were discussed. Commonly available hydrophobic substances used in industrial applications were selected for the research. The aim of using waterproof coatings was to check the possibility to decreasing the susceptibility of high-strength low-alloy S460N steel to cold cracking. During experiments diffusible hydrogen content in deposited metal determination by mercury method, metallographic macro- and microscopic testing and hardness measurements were performed. Investigations showed that waterproof coatings laid on covered electrodes can improve the quality of wet welded joints, by decreasing the Vickers HV10 hardness in heat-affected zone and decreasing the diffusible hydrogen content in deposited metal, which minimalize possibility of cold cracking. Full article

(This article belongs to the Special Issue Underwater Processing of Materials)

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