scholarly journals High Martensitic Steel after Welding with Micro-Jet Cooling in Microstructural and Mechanical Investigations

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 936
Author(s):  
Bożena Szczucka-Lasota ◽  
Tomasz Węgrzyn ◽  
Tadeusz Szymczak ◽  
Adam Jurek
Keyword(s):  
Tensile Strength ◽  
Weld Metal ◽  
Fatigue Limit ◽  
Relative Elongation ◽  
Fatigue Behavior ◽  
Base Material ◽  
Welding Process ◽  
Heat Affect Zone ◽  
Jet Cooling ◽  
Metal Deposit

Modern means of transport will play a significant role in the smart city. In the automotive industry, high-strength steels such as Docol are employed more often. This kind of material is relatively not very well weldable. The main reason is related to the Heat Affect Zone, the region in which cracks occur. Another disadvantage is connected with differences in values of ultimate strength of parent and weld material. The differences can be diminished using the correct welding process, which employs nickel and molybdenum electrode wires at much lower sulfur content. The weld metal deposit contains mainly martensite and bainite with coarse ferrite, while the parent material contains mainly martensite and rather fine ferrite. New technology, micro-jet cooling after the joining process enables to obtain the microstructure of weld metal deposit at acceptable parameters. Welding with micro-jet cooling could be treated as a very promising welding Docol steels process with high industrial application. Results of non-destructive inspections on macro samples corresponded with further destructive test results (tensile strength, hardness, fatigue, metallographic structure analyses). This article aims to verify fatigue behavior of Docol 1200 M steel after welding supported by the cooling using the micro-jet technique. For the first time, micro-jet cooling was used to weld this kind of steel to check the mechanical properties of the joint, especially to determine the fatigue limit. This study is formulated as follows: investigating fatigue resistance of the Docol 1200 M weld manufactured at the cooling process with micro-jets. The joints were produced in the MAG (Metal Active Gas) technology modified by micro-jet cooling. The results collected in the fatigue test were processed in the form of the Wöhler’s S–N diagram following the fatigue limit of the weld examined. All data have indicated the possibility of obtaining a new method of welded joints with high fatigue limit minimum of 480 MPa. It could be important to achieve a tensile strength of 700 MPa while maintaining the best relative elongation at the level of the base material.

Oxygen in Steel WMD after Welding with Micro-Jet Cooling

2013 ◽  
Vol 58 (4) ◽  
pp. 1067-1070 ◽  
Author(s):  
T. Wegrzyn ◽  
J. Piwnik ◽  
D. Hadrys
Keyword(s):  
Mechanical Properties ◽  
Weld Metal ◽  
Welding Process ◽  
Mag Welding ◽  
Mig Welding ◽  
Metallographic Structure ◽  
Jet Cooling ◽  
Welding Technology ◽  
Metal Deposit ◽  
Steel Welds

Abstract Until that moment micro-jet technology was tested only for MIG welding process with argon as a shielded gas. An article presents actual information about innovate welding technology with micro-jet cooling. There are put down information about gases that could be chosen both for MIG/MAG welding and for micro-jet process. There were given information about influence of various micro-jet gases on metallographic structure of steel welds. Mechanical properties of weld was presented in terms of oxygen amount in WMD (weld metal deposit).

Influence of Weld Discontinuities on Strain Controlled Fatigue Behavior of 308 Stainless Steel Weld Metal

1994 ◽  
Vol 116 (2) ◽  
pp. 193-199 ◽  
Author(s):  
K. Bhanu Sankara Rao ◽  
M. Valsan ◽  
R. Sandhya ◽  
S. L. Mannan ◽  
P. Rodriguez
Keyword(s):  
Stainless Steel ◽  
Weld Metal ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Base Material ◽  
Welding Process ◽  
Single Strain ◽  
Damage And Fracture ◽  
Slag Inclusions ◽  
Type 304

Detailed investigations have been performed for assessing the importance of weld discontinuities in strain controlled low cycle fatigue (LCF) behavior of 308 stainless steel (SS) welds. The LCF behavior of 308 SS welds containing defects was compared with that of type 304 SS base material and 308 SS sound weld metal. Weld pads were prepared by shielded metal arc welding process. Porosity and slag inclusions were introduced deliberately into the weld metal by grossly exaggerating the conditions normally causing such defects. Total axial strain controlled LCF tests have been conducted in air at 823 K on type 304 SS base and 308 SS sound weld metal employing strain amplitudes in the range from ±0.25 to ±0.8 percent. A single strain amplitude of ±0.25 percent was used for all the tests conducted on weld samples containing defects. The results indicated that the base material undergoes cyclic hardening whereas sound and defective welds experience cyclic softening. Base metal showed higher fatigue life than sound weld metal at all strain amplitudes. The presence of porosity and slag inclusions in the weld metal led to significant reduction in life. Porosity on the specimen surface has been found to be particularly harmful and caused a reduction in life by a factor of seven relative to sound weld metal. Defect combination of porosity and slag inclusions was found to be more deleterious than the case when either the slag inclusions or porosity was present alone. Discontinuties acted as crack initiation sites and also enhanced crack propagation. The LCF properties of weld samples containing discontinuities have been correlated with the damage and fracture behavior.

scholarly journals Nitrogen And Oxygen Amount In Weld After Welding With Micro-Jet Cooling

2015 ◽  
Vol 60 (2) ◽  
pp. 657-660
Author(s):  
T. Węgrzyn ◽  
J. Piwnik
Keyword(s):  
Mechanical Properties ◽  
Weld Metal ◽  
Welding Process ◽  
Mag Welding ◽  
Mig Welding ◽  
Metallographic Structure ◽  
Jet Cooling ◽  
Metal Deposit ◽  
Steel Welds

AbstractMicro-jet cooling after welding was tested only for MIG welding process with argon, helium and nitrogen as a shielded gases. A paper presents a piece of information about nitrogen and oxygen in weld after micro-jet cooling. There are put down information about gases that could be chosen both for MIG/MAG welding and for micro-jet process. There were given main information about influence of various micro-jet gases on metallographic structure of steel welds. Mechanical properties of weld was presented in terms of nitrogen and oxygen amount in WMD (weld metal deposit).

scholarly journals The Use of Compressed Air for Micro-Jet Cooling After MIG Welding

2016 ◽  
Vol 61 (3) ◽  
pp. 1405-1408
Author(s):  
D. Hadryś ◽  
T. Węgrzyn ◽  
J. Piwnik ◽  
Z. Stanik ◽  
W. Tarasiuk
Keyword(s):  
Weld Metal ◽  
Acicular Ferrite ◽  
Compressed Air ◽  
Steel Weld ◽  
Low Alloy Steel ◽  
Mig Welding ◽  
Jet Cooling ◽  
Metal Deposit ◽  
Steel Weld Metal ◽  
First Time

AbstractThe material selected for this investigation was low alloy steel weld metal deposit (WMD) after MIG welding with micro-jet cooling. The present investigation was aimed as the following tasks: obtained WMD with various amount of acicular ferrite and further analyze impact toughness of WMD in terms of acicular ferrite amount in it. Weld metal deposit (WMD) was first time carried out for MIG welding with micro-jet cooling of compressed air and gas mixture of argon and air. Until that moment only argon, helium and nitrogen were tested as micro-jet gases for MIG/MAG processes. An important role in the interpretation of the results can give methods of artificial intelligence.

Characterization of Local Deformation in Welded Joints Using a Combined Experimental and Numerical Approach

2014 ◽  
Vol 627 ◽  
pp. 241-244 ◽  
Author(s):  
Pawel Kucharczyk ◽  
Sebastian Münstermann
Keyword(s):  
Chemical Composition ◽  
Weld Metal ◽  
Welded Joints ◽  
Base Material ◽  
Welding Process ◽  
Numerical Approach ◽  
Geometrical Model ◽  
Local Deformation ◽  
Heat Treated ◽  
Welded Structure

The microstructure of welded joints differs significantly from that of the base material, what changes their mechanical properties and influences fatigue life. The aim of this work was the investigation of the local deformation field within a butt joint made of 10 mm thick structural steel S355. However, a direct sampling even of the weld metal was impossible due to small dimensions of butt joints. Therefore, the following procedure was utilized in order to manufacture big samples of the microstructure identical to that of the local weldment areas.A geometrical model of the welded structure describing the relevant areas e.g. weld metal, heat-affected zone was established. It was based on the results of the metallographic investigations, hardness mapping and electron-probe-micro-analysis of the local chemical composition. The welding process was numerically simulated using SYSWELD program to estimate the time-temperature-transition (TTT) curves for each identified area. The parameters of the heat input source were calibrated. Afterwards, the material of the defined chemical composition was heat-treated according to the TTT curves. For the validation purpose the heat-treated work pieces were evaluated in terms of microstructure and hardness distribution. Finally, the up-scaled samples of the respective bulk microstructure were manufactured and investigated in monotonic tests.

Recommendations for Submerged Arc Spiral Welding With Optimized CTOD Properties

2018 ◽  
Author(s):  
Martin Liebeherr ◽  
Özlem E. Güngör ◽  
Nuria Sanchez ◽  
Hervé Luccioni ◽  
Nenad Ilic
Keyword(s):  
Weld Metal ◽  
Base Material ◽  
Welding Process ◽  
Experimental Program ◽  
Welding Parameters ◽  
Pipe Production ◽  
Filler Wire ◽  
Crack Tip Opening Displacement ◽  
Wide Range ◽  
Submerged Arc

Many pipe mills may not be familiar with a Crack Tip Opening Displacement (CTOD) requirement on the pipe seam weld, nor will they find easily relevant information in open literature. Influencing — and certainly not independent — factors are: welding parameters, base material and consumable selection. Out of these, the welding parameters such as heat input and cooling rate cannot be varied over a wide range during the pipe production, which means that the leverage is rather limited at the given welding process. The properties of the heat affected zone will be mainly affected by the base material, while the properties of the weld metal will be affected by both, base material and filler wire selection. In particular with respect to the weld metal properties it will be difficult to obtain general quantitative information. For example, a welding consumable supplier will readily provide the properties of the filler wires but would be unable to predict the changes caused by the dilution from any base material in the weld pool and specific welding procedures that may have been used. To support the pipe mills in the selection of the consumables for submerged arc welding, an experimental program was launched with the aim to provide recommendations on how to optimize CTOD toughness of the spiral weld seam. For this, a large number of welds were produced on 20 mm thick X70 coil samples, with eight different filler wire combinations, using a 2-wire (tandem) set-up for both the inside and outside weld. Welding parameters were kept constant. The welding program was applied to two different X70 steels to determine a potential influence of the micro-alloying elements, particularly Nb. The results show clearly that a careful consumable selection is required for obtaining acceptable CTOD toughness in the weld metal. Ni-Mo and Ti-B additions to the weld metal are found to be beneficial with both steel concepts. Mo addition alone both to the ID and OD welds was clearly not a suitable selection.

Application of FIB/SEM/EBSD for Evaluation of Residual Strains and Their Relationship to Weld Metal Hydrogen Assisted Cold Cracking

2012 ◽  
Author(s):  
W. L. Costin ◽  
I. H. Brown ◽  
L. Green ◽  
R. Ghomashchi
Keyword(s):  
Residual Stresses ◽  
Weld Metal ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Ion Beam ◽  
Base Material ◽  
Welding Process ◽  
Cold Cracking ◽  
Predictive Methods ◽  
Residual Strains

Hydrogen assisted cold cracking (HACC) is a welding defect which may occur in the heat affected zone (HAZ) of the base metal or in the weld metal (WM). Initially the appearance of HACC was associated more closely with the HAZ of the base metal. However, recent developments in advanced steel processing have considerably improved the base material quality, thereby causing a shift of HACC to the WM itself. This represents a very serious problem for industry, because most of the predictive methods are intended for prevention of HACC in the HAZ of the base metal, not in the weld metal [1]. HACC in welded components is affected by three main interrelated factors, i.e. a microstructure, hydrogen concentration and stress level [2–4]. In general, residual stresses resulting from the welding process are unavoidable and their presence significantly influences the susceptibility of weld microstructures to cracking, particularly if hydrogen is introduced during welding [5]. Therefore various weldability tests have been developed over the years which are specifically designed to promote HACC by generating critical stress levels in the weld metal region due to special restraint conditions [4, 6–8]. These tests were used to develop predictive methods based on empirical criteria in order to estimate the cracking susceptibility of both the heat-affected zone and weld metal [4]. However, although the relationship between residual stress, hydrogen and HACC has received considerable attention, the interaction of residual stresses and microstructure in particular at microscopic scales is still not well understood [5, 9–21]. Therefore the current paper focuses on the development and assessment of techniques using Focused Ion Beam (FIB), Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction for the determination of local residual strains at (sub) micron scales in E8010 weld metal, used for the root pass of X70 pipeline girth welds, and their relationship to the WM microstructure. The measurement of these strains could be used to evaluate the pre-existing stress magnitudes at certain microstructural features [22].

scholarly journals Mechanical Properties of Plug Welds after Micro-Jet Cooling

2016 ◽  
Vol 61 (4) ◽  
pp. 1771-1776 ◽  
Author(s):  
D. Hadryś
Keyword(s):  
Mechanical Properties ◽  
Weld Metal ◽  
Weld Joint ◽  
Welded Joint ◽  
New Technology ◽  
Mig Welding ◽  
Jet Streams ◽  
Welding Method ◽  
Jet Cooling ◽  
Metal Deposit

Abstract New technology of micro-jet welding could be regarded as a new way to improve mechanical properties of plug welds. The main purpose of that paper was analyzing of mechanical properties of plug welds made by MIG welding method with micro-jet cooling. The main way for it was comparison of plug welds made by MIG welding method with micro-jet cooling and plug welds made by ordinary MIG welding method. It is interesting for steel because higher amount of acicular ferrite (AF) in weld metal deposit (WMD) is obtained in MIG welding method with micro-jet cooling in relation to ordinary MIG welding method. This article presents the influence of the cooling medium and the number of micro-jet streams on mechanical properties of the welded joint. Mechanical properties were described by force which is necessary to destroy weld joint.

scholarly journals Impact Toughness of Steel WMD After TIG Welding

2017 ◽  
Vol 62 (3) ◽  
pp. 1647-1650
Author(s):  
T. Węgrzyn ◽  
J. Piwnik ◽  
Z. Stanik ◽  
D. Węgrzyn ◽  
D. Sieteski
Keyword(s):  
Artificial Intelligence ◽  
Impact Toughness ◽  
Weld Metal ◽  
Alloy Steel ◽  
Gas Mixtures ◽  
Tig Welding ◽  
Low Alloy Steel ◽  
Jet Cooling ◽  
Metal Deposit ◽  
Alloy Weld

AbstractThe material selected for this investigation was low alloy weld metal deposit after TIG welding with various amount of oxygen in weld metal deposit (WMD). After TIG process it is difficult to get proper amount of oxygen in WMD on the level much lower than 350 ppm. The highest impact toughness of low alloy WMD corresponds with the amount of oxygen in WMD above 350 ppm. In the paper focuses on low alloy steel after innovate welding method with micro-jet cooling that could be treated as a chance on rising amount of oxygen in weld. Weld metal deposit (WMD) was carried out for TIG welding with micro-jet cooling with various amount of oxygen in WMD. In that paper various gas mixtures (gas mixtures Ar-O2and Ar-CO2) were tested for micro-jet cooling after TIG welding. An important role in the interpretation of the results can give methods of artificial intelligence.

Weld Hardness Study of P91 Welded Pipes with Post Weld Heat Treatment for Elevated Temperature Application in Power Plants

2015 ◽  
Vol 1115 ◽  
pp. 503-508 ◽  
Author(s):  
Muhammad Sarwar ◽  
Mohd Amin bin Abd Majid
Keyword(s):  
Heat Treatment ◽  
Power Plant ◽  
Weld Metal ◽  
Creep Strength ◽  
Power Plants ◽  
Thermal Power ◽  
Base Material ◽  
Welding Process ◽  
Post Weld Heat Treatment ◽  
Weld Heat

The creep strength-enhanced ferritic (CSEF) steels are undergoing an encouraged use around the world especially in power plant construction. On construction sites, it has always been the target to have no problems in welded joints but premature failures are being encountered. The primary reason of these premature failures is found to be the improper heat treatment that is mandatorily carried out to achieve the required weld hardness. Weld hardness has close relationship with creep strength and ductility of the welded structures. Hence it is important for any weld to achieve certain level of weld hardness. This study aims at ascertaining the importance of Post Welding Heat Treatment (PWHT) in achieving the required hardness in creep-strength enhanced ferritic (CSEF) materials.The study was carried out on the welding of alloy steel ASTM A335 Gr. P-91 with the same base material (ASTM A335 Gr. P-91) by Gas Tungsten Arc Welding (GTAW) process using ER90S-B9 filler wire with pre-heat of 200oC (min) and inter-pass temperature of 300oC (max). After welding, the joints were tested for soundness with Radiography testing. Induction heating was used for heat treatment of P91 pipes during welding and post weld heat treatment. The effect of Post Weld Heat Treatment (PWHT) was investigated on the Weld metal and the Heat Affected Zones (HAZ) by hardness testing. It is perceived that the scattered and higher hardness values, more than 250HB in 2” P91 pipes in the weld metal and in the heat affected zones, can be brought into the lower required level, less than 250HB, with an effective post weld heat treatment at 760°C for 2hrs.It is concluded that PWHT is the most effective way of relieving the welding stresses that are produced due to high heat input in the welding process and to achieve the required level of hardness in the weld as well as in the heat affected zones (HAZ) in thermal power plant main steam piping.

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