Fracture Behaviour of Type 304LN Stainless Steel and Its Welds

Author(s):  
J. S. Dubey ◽  
J. K. Chakravartty ◽  
P. K. Singh ◽  
S. Banerjee

SA312 type 304LN stainless steel material, having closer control over impurities and inclusion content, is the intended piping material in the Advanced Heavy Water Reactors. Deformation, fatigue and fracture behaviour of this material and its weldments have been characterized at ambient temperature and at 558K. The details of the fractographic investigations and stretch zone width measurements are also discussed. The base metals shows high initiation toughness (>500 kJ/m2) and large tearing modulus at ambient and operating temperatures. Shielded Metal Arc Welding (SMAW) weld metal shows much much reduced initiation toughness and tearing resistance in comparison to base metal and Gas Tungsten Arc Welding (GTAW) welds. This is attributed to larger density of second phase inclusions in the SMAW weld metal. SZW measurements give a good alternate estimate of the toughness of the materials. Fatigue crack growth rate in SMAW weld metal was found to be comparable to base metal at higher load ratios.

2013 ◽  
Vol 845 ◽  
pp. 775-778 ◽  
Author(s):  
Toto Triantoro Budi Wardoyo ◽  
S. Izman ◽  
Denni Kurniawan

Effect of variation of the connection (butt joint) in low carbon steel resistance welding (shielded metal arc welding, SMAW) performance is investigated in this paper. Three types of butt joint was varied: square, single V, and double V. The results from tensile test showed that welded specimens are of similar tensile properties with base metal and one another. When hardness test was performed on weld metal, HAZ, and base metal of each specimen,.it was found that weld metal and HAZ were of higher hardness than the base metal. Specimen with square joint exhibits the highest hardness while specimens with single V and double V joints show similar hardness. Microstructure analysis revealed that weld metal of specimen with square joint is of bainite-martensite phases while weld metal of specimens with single V and double V joints are of ferrite-pearlite phases. This difference in microstructure, and hence in hardness, is related to the corresponding heat input during welding.


2013 ◽  
Vol 545 ◽  
pp. 182-187 ◽  
Author(s):  
Nusara Tiyasri ◽  
Bovornchok Poopat

This work aims to develop welding procedure for small diameter longitudinal welded clad pipe made from clad plate. High strength carbon steel base metal bonded with 316L stainless steel clad layer was used in this study. The dissimilar materials at the weld joint and accessibility limitation of small diameter present difficulty in welding process selection to achieve weld soundness. The joint and welding se¬quence are designed to avoid solidification cracking. Nickel base over matching filler is used on the clad side. Typical joint configuration is double V groove weld without clad peel back to minimize the number of passes inside the pipe. Firstly, welding is done on the carbon steel side by using Shielded Metal Arc Welding (SMAW) and Submerged Arc Welding (SAW) with carbon steel electrodes. Then, welding on the clad side is done by using ERNiCrMo-3 filler metal. Two different procedures for the clad side are studied. The first procedure is to weld the clad side by using Gas Tungsten Arc Welding (GTAW) and Gas Metal Arc Welding pulse current (GMAW-pulse) and another procedure is to weld the clad side by using the SAW procedure. Hot cracking was observed in the case of SAW procedure at the clad weld centerline due to high heat input and high level of dilution. Mechanical properties and microstructure are evaluated. Clad weld by use of GTAW and GMAW-pulse could give sound weld metal. The tensile and yield strength of all weld metal were found to be greater than that of base metal and 100% shear failures were observed. Charpy impact energy of weld and HAZ at -10°C was found to be over 100 joules. Hardness of weld and HAZ area are surveyed over the weld cross section to determine local hardening. Additionally intergranular corrosion testing was carried out on the clad weld side and then bend testing was done. No crack was observed. Therefore, GTAW and GMAW-pulse clad weld procedure could give required properties according to clad line pipe standard, reduce cost of production and increase productivity compared to the peel back method.


Author(s):  
Sorush Niknamian

Nowadays, welding of dissimilar metals has become significant. In this process, a number of parameters including but not limited to type of electrode, amount of current, preheating temperature, and welding rate, that are essential to be taken into account. For welding of dissimilar metals, various methods are exploited including shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW). The stimulus for studying welding of 304L stainless steel to pure copper originates from difficulties in joining copper parts of           water-circulating molds to their steel part. In this study, the welding is performed on plates of steel and copper using SMAW, GTAW and combined SMAW+GTAW welding methods with    EL-CuMn2, ENiCrMo-6 and ER70S-4 electrodes. In order to investigate the microstructure and corrosion resistance behavior of welds, the samples were characterized using microstructural study and polarization test. It was observed that among all four welding methods, only combined SMAW+GTAW welding process resulted in successful joint between 304L stainless steel and copper. Both obtained joints possess suitable microstructure and corrosion resistance.


Author(s):  
R Rajasekaran ◽  
AK Lakshminarayanan ◽  
M Vasudevan ◽  
P Vasantharaja

Nuclear grade 316LN austenitic stainless steel weld joints were fabricated using conventional gas tungsten arc welding (GTAW), activated flux gas tungsten arc welding (AGTAW), laser beam welding (LBW) and friction stir welding (FSW) processes. Assessment of weld beads was done by mechanical and metallurgical characterizations. Bead geometry and weld zones were studied by taking macrographs along the transverse side of the weld joints. Metallurgical features of different weld joints were carried out using optical microscopy and scanning electron microscopy. Microhardness distribution across four weld joints was recorded and hardness variations were compared. All weld zone, heat affected zone (HAZ) of GTAW and LBW, thermo-mechanically affected zone (TMAZ) of FSW processes, exhibited higher hardness values than the base metal. Reduced hardness was recorded at HAZ of AGTAW process. This was the result of a considerable grain growth. LBW joint showed the highest hardness value at the center of the fusion zone due to fine equiaxed dendrite morphology. Tensile and impact properties of different welding processes were evaluated and comparisons were made at room temperature. All weld samples displayed high yield strength (YS) and ultimate tensile strength (UTS) with a lower percentage of elongation compared to that of the base metal. FSW joint showed improved YS, UTS and impact toughness compared to other weld joints. This is attributed to the formation of strain-free fine equiaxed grains at stir zone around 5 µm in size with subgrains of 2 µm in size by severe dynamic recrystallization mechanism. Among the fusion welding techniques, AGTAW process exhibited improved toughness, besides almost equal toughness of the base metal due to low δ-Ferrite with high austenite content. Fractography studies of the base metal and different weld samples were carried out by SEM analysis and features were compared.


2020 ◽  
Vol 1012 ◽  
pp. 296-301
Author(s):  
Clélia Ribeiro de Oliveira ◽  
Eloá Lopes Maia ◽  
Solange T. da Fonseca ◽  
Marcelo Martins ◽  
Julián Arnaldo Ávila Díaz ◽  
...  

Superduplex stainless steel alloy exhibit high mechanical and corrosion resistance, which main industrial application is in the petrochemical industry. The manufacture and maintenance of such equipment usually involve welding processes, followed by post-welded heat treatment and it often becomes impossible to apply heat treatments. Thereby, the purpose of this work is to verify the effect of a post-welded heat treatment on shielded metal arc welding in steel grade ASTM A890/A890M - grade 6A. The microstructure in the as-welded condition consisted of austenite, secondary austenite, and ferrite phases and, the post-welded heat treatment condition exhibited only austenite and ferrite. The hardness in the melt zone reached values of 300 HV after welding and, the value was reduced to 260 HV in the post-welded heat treatment condition.


2012 ◽  
Vol 581-582 ◽  
pp. 808-816 ◽  
Author(s):  
Chuaiphan Wichan ◽  
Srijaroenpramong Loeshpahn

The joining of austenitic stainless steel (AISI 201) to low carbon steel sheets (CS) was attempted by gas tungsten arc welding (GTAW) with four types of consumables. The studied consumables were ER308L, ER309L, ER316L stainless steel wires, and AWS A5.18 carbon steel wire. The welding parameters – i.e. the current of 90 A and the welding speed of 62 mm.min-1 – were fixed in all welding operations. The microstructure of weld metal produced by stainless steel consumables consisted of delta ferrite in austenite matrix. The delta ferrite in the form of continuous dendrite was observed in weld metals produced by 308L and 309L fillers. The dendrite of delta ferrite was relatively discontinuous in weld metal produced by 316L filler. The microstructure of weld metal produced by carbon steel filler consisted of equiaxed ferrite and pearlite, similar to that of carbon steel. The corrosion behavior of weld metal was investigated by potentiodynamic method. Specimens were tested in 0.35-wt% NaCl solution saturated by laboratory air at 27°C. It was found that the corrosion potential of weld metal produced by carbon steel filler was considerably lower than those of AISI 201 base metal and weld metals welded using stainless steel consumables. Weld metals produced by stainless steel fillers –308L,309L and316L– exhibited the similar corrosion potentials as that of 201 base metal. The pitting potentials of weld metals produced by 309L, 316L fillers were higher than those of 201 base metal and weld metal produced by 308L filler respectively. It was discussed that the increase of Cr content in weld metals by using 309L filler contained with 24.791 wt% of Cr, or the addition of Cr and Mo in weld metals by using 316L filler contained with 21.347 wt% of Cr and 2 wt% of Mo, promoted the pitting corrosion resistance of weld metal to be comparable with that of Fe-17Cr-3Ni (201) base metal. An emission spectroscopy was applied to quantify the amount of elements in weld metals. By considering the contents of Cr and Mo, the pitting resistance equivalent number (PREN) of each weld metal was calculated. The discussion of the corrosion resistance of weld metals related to PREN and microstructure was made in the paper.


2015 ◽  
Vol 819 ◽  
pp. 57-62 ◽  
Author(s):  
M.F. Mamat ◽  
E. Hamzah ◽  
Z. Ibrahim ◽  
A.M. Rohah ◽  
A. Bahador

In this paper, dissimilar joining of 316L stainless steel to low carbon steel was carried out using gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW). Samples were welded using AWS: ER309L welding electrode for GMAW and AWS: ER316L welding electrode for GTAW process. Determination of mechanical properties and material characterization on the welded joints were carried out using the Instron tensile test machine and an optical microscope respectively. The cross section area of the welded joint consists of three main areas namely the base metal (BM), heat affected zone (HAZ), and weld metal (WM). It was found that, the yield and tensile strengths of welded samples using ER316L filler metal were slightly higher than the welded sample using ER309L welding electrode. All welded samples fractured at low carbon steel base metal indicating that the regions of ER316L stainless steel base metal, ER316L filler metal and heat affected zone (HAZ) have a higher strength than low carbon steel base metal. It was also found that ER316L welding electrode was the best filler to be used for welding two dissimilar metals between carbon and stainless steel.


2012 ◽  
Vol 710 ◽  
pp. 451-456
Author(s):  
Ravi Ranjan Kumar ◽  
P. K. Ghosh

Mechanical and fracture properties of 20MnMoNi55 grade high strength low alloy (HSLA) steel welds have been studied. The weld joints were made using Gas Tungsten Arc Welding (GTAW), Shielded Metal Arc Welding (SMAW) and Pulse Gas Metal Arc Welding (P-GMAW) methods on conventional V-groove (V-Groove) and Narrow groove (NG-13). The base metal and weld metal were characterised in terms of their metallurgical, mechanical and fracture toughness properties by following ASTM procedures. The J-Integral fracture test was carried out using compact tension C(T) specimen for base and weld metal. The fracture toughness and tensile properties of welds have been correlated with microstructure. In conventional V-groove welds prepared by P-GMAW shows the improvement in initiation fracture toughness (JIC) as compared to the weld prepared by SMAW. Similar improvements in tensile properties have also been observed. This is attributed to reduction in co-axial dendrite content due to lower heat input during P-GMAW process as compared to SMAW. In the narrow groove P-GMA weld prepared at f value of 0.15 has shown relative improvement of JIC as compared to that of the weld prepared by SMAW process.


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