Use of a Reductive Carbon Monoxide Atmosphere in Arc Welding of Microalloyed Steels

2019 ◽  
Vol 945 ◽  
pp. 543-548 ◽  
Author(s):  
E.A. Ivanaysky ◽  
A.V. Ishkov ◽  
A.A. Ivanaysky
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Welded Joints ◽  
Arc Welding ◽  
Microalloyed Steels ◽  
Metallographic Analysis ◽  
Welded Steel ◽  
Reducing Atmosphere ◽  
Oxidative Processes ◽  
Steel Joints

The possibility of making welded steel joints using arc welding in a reducing medium of carbon monoxide was studied. A method was proposed to eliminate its negative biological effect by heating the feed gas above its flash point, followed by oxidation till carbon dioxide was obtained. Welding modes have been selected to ensure the formation of a quality welded joint. Comparative studies of welded joints obtained using an oxidizing atmosphere of carbon dioxide and a reducing atmosphere of carbon monoxide were carried out. A chemical and metallographic analysis of welded joints was performed. The thermodynamic substantiation of chemical reactions in which carbon and microalloying additives can participate was presented. It was established that the main difference between the proposed welding method and those used at present was the suppression of oxidative processes in liquid metal due to the presence of a reducing atmosphere.

Welding of Cold-Resistant Micro-Alloed Steels 10HSNDA and 15HSNDA in the Atmosphere of Carbon Monoxide (II)

2020 ◽  
Vol 992 ◽  
pp. 523-528
Author(s):  
Alexey V. Ishkov ◽  
E.A. Ivanayskiy ◽  
Valeriy I. Ivanov
Keyword(s):  
Carbon Monoxide ◽  
Arc Welding ◽  
Cold Resistance ◽  
Low Cost ◽  
High Strength ◽  
Metallographic Analysis ◽  
Steel Composition ◽  
Reducing Atmosphere ◽  
The North ◽  
Microalloying Elements

Micro-alloyed steels are widely used in the manufacture of critical welded structures operating under extreme conditions of the North. Microalloying of V, Nb and B is a simple and effective method of transferring known grades of structural steel and alloys to the category of increased and high strength, cold resistance, etc. The possibility of arc welding of steels grade 10CrSiNiAl and 15CrSiNiAl (10, 15ХСНДА in Russian), initially alloyed with trace amounts of niobium and vanadium to increase their cold resistance in carbon monoxide is considered. It is established that the use of the specified reducing atmosphere prevents the oxidation of the weld metal. The thermodynamic substantiation of the chemical reactions of microalloying elements proceeding in the weld pool, leading to the preservation of the steel composition, is presented. The chemical and metallographic analysis of welds was performed. The efficiency of using low-cost CO, or its mixtures with CO2, as substitutes for expensive argon and helium, when welding micro alloyed steels is shown.

scholarly journals Controlled atmosphere GMAW welding of transportation vehicles and production machines parts made from 30MnB5 steel

2018 ◽  
Vol 216 ◽  
pp. 03001 ◽  
Author(s):  
Evgeny Ivanayskiy ◽  
Aleksei Ishkov ◽  
Aleksandr Ivanayskiy ◽  
Iakov Ochakovskii
Keyword(s):  
Mechanical Properties ◽  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Chemical Composition ◽  
Controlled Atmosphere ◽  
Shielding Gas ◽  
Reducing Atmosphere ◽  
Metal Composition ◽  
Gmaw Welding ◽  
Welding Materials

The paper studies the influence of shielding gas on the composition and the structure of weld joint metal of 30MnB5 steel applied in essential parts of automobiles and tractors. The welding was performed in inert, oxidizing and reducing atmospheres. It was established that TIG welding with argon used as shielding gas did not provide the required mechanical properties when using conventional welding materials. Carbon dioxide during MAG welding caused partial burning of alloying elements. Carbon monoxide used as shielding gas was proved to form reducing atmosphere enabling to obtain chemical composition close to the base metal composition. Metallographic examinations were carried out. The obtained results provided full-strength weld, as well as the required reliability and durability of welded components and joints.

scholarly journals Review of Fatigue Assessment Methods for Welded Steel Structures

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Boris Fuštar ◽  
Ivan Lukačević ◽  
Darko Dujmović
Keyword(s):  
Welded Joints ◽  
Fatigue Crack Initiation ◽  
High Stress ◽  
Steel Structures ◽  
Assessment Methods ◽  
Stress Concentrations ◽  
Additional Material ◽  
Welded Steel ◽  
Fatigue Assessment ◽  
Steel Joints

Due to high stress concentrations, welded joints represent the most common locations of fatigue crack initiation in steel structures that are prone to fatigue. Welding affects material properties by the process of heating, cooling, and combining basic and additional material. Since welding is the primary process of joining elements in steel structures, it is obvious that fatigue assessment during the design and maintenance process becomes inevitable. There are many fatigue assessment methods of welded joints, but their precision remains questionable. This paper represents a review of the most common fatigue assessment methods used for welded steel joints. As a result of this review, areas that require additional research are highlighted.

Thickness Effect Criterion for Fatigue Strength Evaluation of Welded Steel Structures

1993 ◽  
Vol 115 (1) ◽  
pp. 58-65 ◽  
Author(s):  
J. Yagi ◽  
S. Machida ◽  
M. Matoba ◽  
Y. Tomita ◽  
I. Soya
Keyword(s):  
Welded Joints ◽  
Steel Structures ◽  
Point Of View ◽  
Thickness Effect ◽  
Welded Steel ◽  
Cruciform Joints ◽  
Loading Mode ◽  
Heavy Section ◽  
Weld Profile ◽  
Steel Joints

From a practical point of view, some measures to reduce the thickness effect backed by a reasonable criterion are required for fabricating structures with heavy section plates. In this study, the thickness effect was investigated by systematic experiments on welded steel joints with thicknesses ranging from 10 to 80 mm. Cruciform joints and T-joints with improved weld by overall profiling or toe-grinding were tested under pulsating tension and under pulsating bending, respectively. These experimental results were analyzed together with the previous results of as-welded joints. As a result, it was concluded that the thickness effect exponents for various conditions may be classified into three categories according to the combination of joint type and loading mode. As-welded joints under bending stress have the steepest thickness effect exponent of −1/3, while as-welded joints under tension with an exponent of −1/5 is milder in thickness effect than that specified in the existing codes. If the weld profile is improved by grinding, the thickness effect becomes much milder to an exponent of −1/10. The as-weld joints with constant-sized attachments also have an exponent of −1/10. Furthermore, thickness effect dependence on fatigue life and thickness effect under random stress were investigated. Based on these results, this study proposes a new evaluation criterion for design purposes.

scholarly journals Effect of weld metal composition on impact toughness properties of shielded metal arc welded ultra-high hard armor steel joints

2020 ◽  
Vol 29 (1) ◽  
pp. 186-194
Author(s):  
V. Balaguru ◽  
Visvalingam Balasubramanian ◽  
P. Sivakumar
Keyword(s):  
Impact Toughness ◽  
Weld Metal ◽  
Welded Joints ◽  
Weight Ratio ◽  
High Hardness ◽  
High Strength ◽  
Solidification Mode ◽  
Austenitic Phase ◽  
Ferrite Number ◽  
Steel Joints

AbstractNowadays, ultra-high hard armor (UHA) steels are employed in armor tracked vehicle (ATV) construction because of their high hardness, high strength to weight ratio, and excellent toughness. UHA steels are usually welded using austenitic stainless steel (ASS) welding consumables, to avoid hydrogen-induced cracking (HIC). The use of ASS consumables to weld the above steel was the only available remedy because of higher solubility of hydrogen in the austenitic phase. In this investigation, an attempt was made to investigate the effect of ASS consumables (with different Creq/Nieq ratio) on solidification mode, impact toughness and microstructural characteristics of shielded metal arc (SMA) welded UHA steel joints. The welded joints were characterised based on impact toughness properties, hardness, and microstructural features. As the ferrite number increases with an increase in Creq/Nieq ratio result in different solidification mode (A, FA, F). It is also found that ferrite number of weld metal has appreciable influence on impact toughness and has inversely proportional relationship with impact toughness of the welded joints.

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