scholarly journals Improving the mechanical properties of PHS laser welded joints by adding Ni foil to suppress δ-ferrite

2020 ◽  
Vol 9 (3) ◽  
pp. 5184-5193 ◽  
Author(s):  
Xiaming Chen ◽  
Xiaonan Wang ◽  
Qian Sun ◽  
Zengrong Hu ◽  
Pengcheng Huan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Welded Joints ◽  
Δ Ferrite

scholarly journals Microstructure and Mechanical Properties of Modern 11%Cr Heat-Resistant Steel Weld Joints

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3430
Author(s):  
Grzegorz Golański ◽  
Jacek Słania ◽  
Marek Sroka ◽  
Paweł Wieczorek ◽  
Michał Urzynicok ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Welded Joints ◽  
Martensitic Steel ◽  
Base Material ◽  
Hardness Measurement ◽  
Power Industry ◽  
Strength Properties ◽  
Typical Structure ◽  
Δ Ferrite ◽  
The Impact

In addition to good high-temperature creep resistance and adequate heat resistance, steels for the power industry must have, among other things, good weldability. Weldability of such steels is one of the criteria determining whether or not the material is suitable for applications in the power industry. Therefore, when materials such as martensitic steel Thor 115 (T115) are introduced into the modern power industry, the quality and properties of welded joints must be assessed. The paper presents the results of metallographic and mechanical investigations of T115 martensitic steel welded joints. The analysis was carried out on joints welded with two filler metals: WCrMo91 (No. 1) and EPRI P87 (No. 2). The scope of the investigations included: microstructural investigations carried out using optical, scanning and transmission electron microscopy and mechanical testing, i.e., Vickers microhardness and hardness measurement, static tensile test and impact test. The macro- and microstructural investigations revealed correct structure of the weld, without welding imperfections. The microstructural investigations of joint No. 1 revealed a typical structure of this type of joint, i.e., the martensitic structure with numerous precipitates, while in joint No. 2, the so-called Nernst’s layers and δ-ferrite patches were observed in the weld fusion zone as well as the heat affected zone (HAZ). The mechanical properties of the test joints met the requirements for the base material. A slight influence of the δ-ferrite patch on the strength properties of joint No. 2 was observed, and its negative effect on the impact energy of HAZ was visible.

Autogenous Tungsten Inert Gas and Gas Tungsten Arc With Filler Welding of Dissimilar P91 and P92 Steels

2018 ◽  
Vol 140 (2) ◽  
Author(s):  
Chandan Pandey ◽  
Manas Mohan Mahapatra ◽  
Pradeep Kumar ◽  
N. Saini
Keyword(s):  
Mechanical Properties ◽  
Microstructure Evolution ◽  
Welded Joints ◽  
Welding Process ◽  
Postweld Heat Treatment ◽  
Inert Gas ◽  
P92 Steel ◽  
Gas Tungsten Arc ◽  
Δ Ferrite ◽  
Gas Tungsten

Creep strength ferritic/martensitic modified 9Cr-1Mo-V-Nb (P91) steel also designated as ASTM A335 and P92 steel are used for piping, cladding, ducts, wrappers, and the pressure vessel in Gen IV nuclear reactors. In the present investigation, a comparative study of the effect of autogenous tungsten inert gas welding (A-TIG) with double pass and multipass gas tungsten arc (GTA) welding with filler on microstructure evolution in the weld fusion zone and the mechanical properties of P91 and P92 steel welded joints was carried out. The microstructure evolution was studied in as-welded and postweld heat treatment (PWHT) condition. The study also focused on the evolution of δ-ferrite patches and their influence on the tensile properties of welded joints. PWHT was carried out at 760 °C with durations from 2 to 6 h. To study the effect of δ-ferrite evolution on mechanical properties, Charpy toughness, microhardness, and tensile tests were performed. The acceptable microstructure and mechanical properties were obtained after the 6 h of PWHT for A-TIG arc welding process while for GTA weld with filler wire, it was obtained after the 2 h of PWHT at 760 °C.

scholarly journals The Microstructure and Mechanical Properties of Multi-Strand, Composite Welding-Wire Welded Joints of High Nitrogen Austenitic Stainless Steel

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2944 ◽  
Author(s):  
Jianguo Li ◽  
Huan Li ◽  
Yu Liang ◽  
Pingli Liu ◽  
Lijun Yang
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Welded Joints ◽  
Heat Input ◽  
Weld Seam ◽  
High Heat ◽  
High Nitrogen ◽  
Welding Wire ◽  
Δ Ferrite ◽  
High Heat Input

A multi-strand composite welding wire was applied to join high nitrogen austenitic stainless steel, and microstructures and mechanical properties were investigated. The electrical signals demonstrate that the welding process using a multi-strand composite welding wire is highly stable. The welded joints are composed of columnar austenite and dendritic ferrite and welded joints obtained under high heat input and cooling rate have a noticeable coarse-grained heat-affected zone and larger columnar austenite in weld seam. Compared with welded joints obtained under the high heat input and cooling rate, welded joints have the higher fractions of deformed grains, high angle grain boundaries, Schmid factor, and lower dislocation density under the low heat input and cooling rate, which indicate a lower tensile strength and higher yield strength. The rotated Goss (GRD) ({110}⟨1 1 ¯ 0⟩) orientation of a thin plate and the cube (C) ({001}⟨100⟩) orientation of a thick plate are obvious after welding, but the S ({123}⟨63 4 ¯ ⟩) orientation at 65° sections of Euler’s space is weak. The δ-ferrite was studied based on the primary ferrite solidification mode. It was observed that low heat input and a high cooling rate results in an increase of δ-ferrite, and a high dislocation density was obtained in grain boundaries of δ-ferrite. M23C6 precipitates due to a low cooling rate and heat input in the weld seam and deteriorates the elongation of welded joints. The engineering Stress–strain curves also show the low elongation and tensile strength of welded joints under low heat input and cooling rate, which is mainly caused by the high fraction of δ-ferrite and the precipitation of M23C6.

scholarly journals Characterization of Mechanical Heterogeneity in Dissimilar Metal Welded Joints

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4145
Author(s):  
He Xue ◽  
Zheng Wang ◽  
Shuai Wang ◽  
Jinxuan He ◽  
Hongliang Yang
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Welded Joints ◽  
Structural Integrity ◽  
Material Interfaces ◽  
Mechanical Heterogeneity ◽  
Finite Element Software ◽  
Dissimilar Metal ◽  
Stress Changes

Dissimilar metal welded joints (DMWJs) possess significant localized mechanical heterogeneity. Using finite element software ABAQUS with the User-defined Material (UMAT) subroutine, this study proposed a constitutive equation that may be used to express the heterogeneous mechanical properties of the heat-affected and fusion zones at the interfaces in DMWJs. By eliminating sudden stress changes at the material interfaces, the proposed approach provides a more realistic and accurate characterization of the mechanical heterogeneity in the local regions of DMWJs than existing methods. As such, the proposed approach enables the structural integrity of DMWJs to be analyzed in greater detail.

Vibratory weld conditioning during gas tungsten arc welding of al 5052 alloy on the mechanical and micro-structural behavior

2020 ◽  
Vol 17 (6) ◽  
pp. 831-836
Author(s):  
M. Vykunta Rao ◽  
Srinivasa Rao P. ◽  
B. Surendra Babu
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Welded Joints ◽  
Great Influence ◽  
Welding Process ◽  
Microstructural Characterization ◽  
Content Type ◽  
Average Grain Size

Purpose Vibratory weld conditioning parameters have a great influence on the improvement of mechanical properties of weld connections. The purpose of this paper is to understand the influence of vibratory weld conditioning on the mechanical and microstructural characterization of aluminum 5052 alloy weldments. An attempt is made to understand the effect of the vibratory tungsten inert gas (TIG) welding process parameters on the hardness, ultimate tensile strength and microstructure of Al 5052-H32 alloy weldments. Design/methodology/approach Aluminum 5052 H32 specimens are welded at different combinations of vibromotor voltage inputs and time of vibrations. Voltage input is varied from 50 to 230 V at an interval of 10 V. At each voltage input to the vibromotor, there are three levels of time of vibration, i.e. 80, 90 and 100 s. The vibratory TIG-welded specimens are tested for their mechanical and microstructural properties. Findings The results indicate that the mechanical properties of aluminum alloy weld connections improved by increasing voltage input up to 160 V. Also, it has been observed that by increasing vibromotor voltage input beyond 160 V, mechanical properties were reduced significantly. It is also found that vibration time has less influence on the mechanical properties of weld connections. Improvement in hardness and ultimate tensile strength of vibratory welded joints is 16 and 14%, respectively, when compared without vibration, i.e. normal weld conditions. Average grain size is measured as per ASTM E 112–96. Average grain size is in the case of 0, 120, 160 and 230 is 20.709, 17.99, 16.57 and 20.8086 µm, respectively. Originality/value Novel vibratory TIG welded joints are prepared. Mechanical and micro-structural properties are tested.

scholarly journals Microstructure and Mechanical Properties of Heat-Affected Zone of Repeated Welding AISI 304N Austenitic Stainless Steel by Gleeble Simulator

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 773
Author(s):  
Y.H. Guo ◽  
Li Lin ◽  
Donghui Zhang ◽  
Lili Liu ◽  
M.K. Lei
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Impact Energy ◽  
Heat Affected Zone ◽  
Ferrite Content ◽  
Equipment Safety ◽  
Microstructure And Mechanical Properties ◽  
Δ Ferrite ◽  
The Impact

Heat-affected zone (HAZ) of welding joints critical to the equipment safety service are commonly repeatedly welded in industries. Thus, the effects of repeated welding up to six times on the microstructure and mechanical properties of HAZ for AISI 304N austenitic stainless steel specimens were investigated by a Gleeble simulator. The temperature field of HAZ was measured by in situ thermocouples. The as-welded and one to five times repeated welding were assigned as-welded (AW) and repeated welding 1–5 times (RW1–RW5), respectively. The austenitic matrices with the δ-ferrite were observed in all specimens by the metallography. The δ-ferrite content was also determined using magnetic and metallography methods. The δ-ferrite had a lathy structure with a content of 0.69–3.13 vol.%. The austenitic grains were equiaxial with an average size of 41.4–47.3 μm. The ultimate tensile strength (UTS) and yield strength (YS) mainly depended on the δ-ferrite content; otherwise, the impact energy mainly depended on both the austenitic grain size and the δ-ferrite content. The UTS of the RW1–RW3 specimens was above 550 MPa following the American Society of Mechanical Engineers (ASME) standard. The impact energy of all specimens was higher than that in ASME standard at about 56 J. The repeated welding up to three times could still meet the requirements for strength and toughness of welding specifications.

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