Hydrogen and Oxygen Pick-Up in Hyperbaric TIG Welding of Supermartensitic 13% Cr Stainless Steel With Matching Filler Wire

2005 ◽  
Author(s):  
Ragnhild Aune ◽  
Hans Olav Knagenhjelm ◽  
Ansgar S. Ha˚rsvær
Keyword(s):  
Stainless Steel ◽  
Water Vapor ◽  
Weld Metal ◽  
Hydrogen Content ◽  
Tig Welding ◽  
Load Test ◽  
Chamber Pressure ◽  
Filler Wire ◽  
Shielding Gas ◽  
Single Edge

The possible sources causing weld metal hydrogen and oxygen pick-up during offshore hyperbaric tie-in TIG welding have been identified and simulated at a hyperbaric chamber pressure of 12 bar, i.e. 110 meter sea depth. The base material was supermartensitic 13% Cr stainless steel. Matching filler wire was used. The weld metal hydrogen and oxygen pick-up from water vapor in the shielding and chamber gases has been investigated by girth welding of pipes. Moist chamber gas seems to have insignificant effect on hydrogen and oxygen pick-up. The largest contribution is from moist shielding gas. Most of the hydrogen content in the supermartensitic welds is diffusible. By applying post-heat, it is possible to reduce the hydrogen content in the weld metal. Microcracks in the cap were observed for welds deposited with 14 mbar water vapor in the shielding gas (117 ppm) and above. Microcracks in the root welds were not observed, which was also confirmed for self restrained cracking tests. During constant load test at 150 MPa simulating hydrostatic testing of pipelines, the microcracks grew, and for the weld deposited with fully moistened shielding gas (175 ppm), a macrocrack appeared in the centre of the capping pass longitudinally to the welding direction. Crack Tip Opening Displacement (CTOD) values based on Single Edge Notched Bend (SENB) testing were all low, and the high constraint of the SENB specimen did not show any effects of hydrogen on fracture toughness. CTOD values based on Single Edge Notched Tension (SENT) testing decreased with increasing shielding gas moisture contents. For specimens without microcracks it was possible to increase the CTOD (SENT) values by post-heat, close to the toughness observed for specimens deposited with dry shielding gas.

Effect of Ar-N2 Mixed Gas on Morphology and Microstructure of Type 316L Stainless Steel TIG Weld Metal

2011 ◽  
Vol 295-297 ◽  
pp. 1919-1924 ◽  
Author(s):  
Kuang Hung Tseng ◽  
Kai Chieh Hsien
Keyword(s):  
Stainless Steel ◽  
Weld Metal ◽  
316L Stainless Steel ◽  
Welding Process ◽  
Ferrite Content ◽  
Shielding Gas ◽  
Mixed Gas ◽  
Nitrogen Gas ◽  
Type 316L ◽  
Type 316L Stainless Steel

The aim of the present work was to investigate the effects of specific nitrogen gas additions to argon shielding gas on morphology and microstructure of austenitic stainless steel TIG welds. An autogenous TIG welding process was applied on type 316L stainless steel to produce a bead-on-plate weld. The ferrite content of weld metal was measured using a Feritscope. The results indicated that the arc voltage increase as the amount of nitrogen gas added to the argon atmosphere increases. The retained ferrite content of type 316L stainless steel TIG weld metal decreased rapidly as nitrogen gas addition to the argon shielding gas was increased.

Influence of Argon-Nitrogen Gas to Balance the Microstructure in the Welding of Super Duplex Stainless Steel

2016 ◽  
Vol 836 ◽  
pp. 165-172
Author(s):  
Suheni
Keyword(s):  
Stainless Steel ◽  
Weld Metal ◽  
Duplex Stainless Steel ◽  
Heat Input ◽  
Oil And Gas ◽  
Austenite Phase ◽  
Super Duplex Stainless Steel ◽  
Shielding Gas ◽  
Input Variables ◽  
Protective Gas

Super duplex stainless steel is steel that has a corrosion resistance and good mechanical strength so that used in industry especially in oil and gas and petrochemical industry. In use in the field is often used for the connection process by welding methods. To produce good welds, it should be noted that the welding procedures and parameters used , especially the heat input. In this study is used the heat input variables shielding gas composition to determine how much influence on the balance of ferrite - austenite phase structure in the weld stainless steels SAF 2507 super duplex with tungsten inert gas welding method (TIG). Heat input varied by applying different welding speed 1,3,4 and 5 mm /sec while the shielding gas is used 100 % argon, 98 % argon + 2 % nitrogen and 95 % argon + 5 % nitrogen. The result showed that at different welding speeds generated depth and width of the weld metal which is different. Likewise the use of protective gas will produce a different ratio wide and deep of weld metal which is different. By using protective gas 95 % argon + 5 % nitrogen squeak - ausenit phase, resulting in weld metal that is relatively balanced than others. On a slow welding in addition to produce a large heat input also produces weld metal hardness at high and affect the growth of the austenite phase. The higher the heat input ( 2,280 kJ / mm ) , the lower the austenite phase in the weld metal.

Effect of shielding gas combination on microstructure and mechanical properties of MIG welded stainless steel 316

2021 ◽  
Vol 63 (1) ◽  
pp. 97-101
Author(s):  
İsmail Açar ◽  
Behçet Gülenç
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Stainless Steel ◽  
Weld Metal ◽  
Base Metal ◽  
Welding Process ◽  
Bending Test ◽  
Welding Parameters ◽  
Microstructural Properties ◽  
Shielding Gas

Abstract The quality of welded joints depends on the most optimal welding parameters and the selection of shielding gas type. The shielding gas was selected for joining stainless steels through gas metal arc welding methods by considering properties such as chemical-metallurgical interaction of shielding gas and the molten weld metal during the welding process, heat transmission capability of the gas and cost. In this study, the effect of different shielding gas combinations on the mechanical and microstructural properties of 316 austenitic stainless steel joined by the metal inert gas (MIG) welding method was investigated. In the welding process, pure argon (100 % Ar), 98.5 % Ar + 1.5 % H2 and 95 % Ar + 5 % H2 were used as shielding gases. Tensile, hardness, and bending tests were conducted to determine mechanical properties of the welded samples. In addition, metallographic examinations were carried out to detect the macrostructural and microstructural properties of weld zones. According to the results obtained from the study, the highest tensile strength was obtained from the joints welded using 100 % Ar shielding gas. When the addition of H2 into the Ar gas increased, the tensile strength of the welded samples decreased. As a result of the tensile test, fractures occurred in the base metal in all welded samples. In all welding parameters, the hardness of the weld metal was lower as compared to the heat affected zone (HAZ) and the base metal. As a result of the bending test, crack and tearing defects were found in the weld zone.

Controlling the Ferrite/Austenite Phase Balance of SAF 2707HD Hyperduplex Stainless Steel Weldment

2013 ◽  
Vol 748 ◽  
pp. 138-143
Author(s):  
Muhammad Anis ◽  
Rini Riastuti ◽  
Permana Hariansyah ◽  
Mohammad Fadli ◽  
Fisca Sunandar Arif ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Weld Metal ◽  
Stainless Steels ◽  
Heat Input ◽  
Volume Fraction ◽  
Nitrogen Addition ◽  
Limited Range ◽  
Austenite Phase ◽  
Shielding Gas ◽  
Phase Balance

Hyperduplex, as a new class of duplex stainless steels, having high Cr and Mo present excellent combination of mechanical and corrosion resistance, due to their strict composition control and ferrite/austenite phase balance. This balance may, however, be disturbed during welding in both the weld metal and the Heat Affected Zone (HAZ) due to the rapid cooling rates. Those may lead to loss of the good corrosion and mechanical properties of the weldments. The present investigation is to establish the effect of heat input and the nitrogen addition in the argon shielding gas, for controlling the microstructure of hyperduplex stainless steels welded by the Gas Tungsten Arc Welding (GTAW) technique autogeneously. Hyperduplex stainless steel in the form of tube having outside diameter of 32 mm and thickness of 2 mm, was welded using limited range of heat input to control the microstructure in the HAZ, and using the nitrogen addition of 2-5% into argon shielding gas to control the ferrite/austenite phase balance of the weld metal. The microstructure of the weldment was examined by calculating the volume fraction of ferrite and austenite phases. The result shows that the heat input of 0,6 kJ/mm gives the optimum ferrite/austenite phase balance in the HAZ. The addition of 2% nitrogen into argon shielding gas is recommended to give the optimum balance of ferrite/austenite phases in weld metal in addition to the heat input employed. The heat input higher than 0,6 kJ/mm promoted sigma phase at the HAZ as well as at the weld metal particularly when welded with addition of more than 2% nitrogen in the argon shielding gas.

Development of Optimized Welding Consumable for Joining Type 410 Martensitic Stainless Steel

2019 ◽  
Author(s):  
Benjamin J. Lawson ◽  
Boian T. Alexandrov ◽  
Joseph C. Bundy ◽  
David Benson ◽  
Jorge A. Penso
Keyword(s):  
Stainless Steel ◽  
Weld Metal ◽  
Martensitic Stainless Steel ◽  
Ferrite Content ◽  
Filler Wire ◽  
Delta Ferrite ◽  
Welding Consumable ◽  
Fresh Martensite ◽  
Steel Welds ◽  
Welding Consumables

Abstract Type 410 martensitic stainless steel is used in some downstream hydro-processing installations, due to its good resistance to sulfide corrosion and chloride stress corrosion cracking. Industry experience with Type 410 steel welds, using generic welding consumables, has shown difficulties in meeting the weld metal and HAZ hardness and toughness requirements. Recent research has pointed out the wide composition specifications of Type 410 base metal and welding consumables as the leading cause for significant hardness and toughness variations, related to exceeding the A1 temperature during PWHT and formation of fresh martensite, and to retention of significant amounts of delta ferrite. Predictive equations for the A1 temperature and the content of retained delta ferrite were used to identify optimal composition for Type 410 welding consumables with delta ferrite content below 20% and A1 temperature close to the upper end of the ASME specified PWHT range. Experimental metal core filler wire was manufactured and tested to validate the A1 temperature and delta ferrite content. A test weld in Type 410 steel was produced with the new filler wire and subjected to PWHT, metallurgical characterization, and mechanical testing. The weld metal and HAZ properties met the corresponding NACE and ASME hardness and toughness requirements.

Effects of TIG Pulse Current and Nitrogen Content in Argon Shielding Gas on Microstructure and Mechanical Properties of 15Cr-4Ni-8Mn-1.3Cu Stainless Steel Weld Metal

2014 ◽  
Vol 931-932 ◽  
pp. 306-311
Author(s):  
Pragassak Petarporn ◽  
Gobboon Lothongkum ◽  
Ekkarut Viyanit ◽  
Amnuaysak Chianpairot
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Weld Metal ◽  
Nitrogen Content ◽  
Pulse Current ◽  
Shielding Gas ◽  
Delta Ferrite ◽  
Microstructure And Mechanical Properties ◽  
Steel Weld Metal ◽  
Pulse Welding

The TIG pulse welding of 15Cr-4Ni-8Mn-1.3Cu austenitic stainless steel at pulse currents of 130 and 160 A with Argon shielding gases containing 0%, 5% and 10% (v/v) Nitrogen was investigated. The effects of pulse current and Nitrogen content in Argon shielding gas on the microstructure and mechanical properties of weld metal were studied. Based on the results found in this study, the nitrogen content in weld metal was found to increase with increasing nitrogen content in argon shielding gas and pulse current. With the addition of nitrogen in Argon shielding gas, the morphology of delta-ferrites was changed from the conventional TIG pulse welding using pure Argon shielding gas where both lathy and vermicular types were found. However, with the Nitrogen + Argon shielding gas, only vermicular type was observed. Moreover, the arm spacing of delta-ferrite can be enlarged by increasing the pulse current. Those results are the reason for the observed decrease in tensile strength and percent elongation with increasing nitrogen content in argon shielding gas and the pulse current.

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