Study on Fatigue Performance of Pulsed Tungsten Inert Gas Welding Joint of Duplex Stainless Steel Thin Tube

To solve the shortage of austenite phase precipitation caused by nitrogen loss in the welding process of UNS S2205 duplex stainless steel (DSS), shielding gas nitriding was investigated by adding different N<sub>2</sub> contents in Ar shielding gas during the welding process. A good thin...

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Main Authors: Chaofei Yang, Wenjian Zheng, Renfu Wang, Jiajia Niu, Lei Sun, Mao Cheng, Xianjing Lu, Zhou Zhou, Jianguo Yang
Format: Article
Language:English
Published: MDPI AG 2023-12-01
Series:Materials
Subjects:
Online Access:https://www.mdpi.com/1996-1944/17/1/109
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author Chaofei Yang
Wenjian Zheng
Renfu Wang
Jiajia Niu
Lei Sun
Mao Cheng
Xianjing Lu
Zhou Zhou
Jianguo Yang
author_facet Chaofei Yang
Wenjian Zheng
Renfu Wang
Jiajia Niu
Lei Sun
Mao Cheng
Xianjing Lu
Zhou Zhou
Jianguo Yang
author_sort Chaofei Yang
collection DOAJ
description To solve the shortage of austenite phase precipitation caused by nitrogen loss in the welding process of UNS S2205 duplex stainless steel (DSS), shielding gas nitriding was investigated by adding different N<sub>2</sub> contents in Ar shielding gas during the welding process. A good thin-walled pipe butt joint was formed using the pulsed tungsten inert gas (P-TIG) welding method with Ar-N<sub>2</sub> shielding gas. High cycle fatigue tests of the weld joints were conducted to study the effect of shielding gas nitriding on the fatigue properties. Fatigue tests at three stress levels of 225 MPa, 270 MPa, and 360 MPa were carried out on the weld joints with different N<sub>2</sub> contents, and the fatigue samples were all fractured in the high temperature heat-affected zone (H-HAZ). Within the current process parameters, the fatigue life of the 4 vol.% N<sub>2</sub> welded joints was optimal. Fatigue striations appeared in the fatigue crack propagation zone, and the transient fracture zone was similar to the tensile fracture. Under the low-stress level, the area of the crack propagation zone under 4 vol.% N<sub>2</sub> was the highest, the tear ridges all expanded around the crack source area, and the fatigue crack propagation zone presented a radial distribution. The proliferation and expansion of dislocations were mainly carried out in the austenite grains, and the dislocation density of the fatigue specimens under 4 vol.% N<sub>2</sub> was smaller than that of the Ar specimens. Shielding gas nitriding effectively improved the balance of the two-phase ratio and the hardness of austenite phase, optimized the internal slip system, inhibited the proliferation of dislocations in the austenite phase, and improved the fatigue life of weld joints.
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spelling doaj.art-95cb5836481644be812cbb318b4cabc02024-01-10T15:02:37ZengMDPI AGMaterials1996-19442023-12-0117110910.3390/ma17010109Study on Fatigue Performance of Pulsed Tungsten Inert Gas Welding Joint of Duplex Stainless Steel Thin TubeChaofei Yang0Wenjian Zheng1Renfu Wang2Jiajia Niu3Lei Sun4Mao Cheng5Xianjing Lu6Zhou Zhou7Jianguo Yang8Luoyang Ship Material Research Institute, Luoyang 471000, ChinaLuoyang Ship Material Research Institute, Luoyang 471000, ChinaLuoyang Ship Material Research Institute, Luoyang 471000, ChinaLuoyang Ship Material Research Institute, Luoyang 471000, ChinaLuoyang Ship Material Research Institute, Luoyang 471000, ChinaZhejiang Academy of Special Equipment Science, Hangzhou 310020, ChinaZhejiang Academy of Special Equipment Science, Hangzhou 310020, ChinaCollege of Mechanical Engineering, Zhejiang University of Technology, Hangzhou 310014, ChinaCollege of Mechanical Engineering, Zhejiang University of Technology, Hangzhou 310014, ChinaTo solve the shortage of austenite phase precipitation caused by nitrogen loss in the welding process of UNS S2205 duplex stainless steel (DSS), shielding gas nitriding was investigated by adding different N<sub>2</sub> contents in Ar shielding gas during the welding process. A good thin-walled pipe butt joint was formed using the pulsed tungsten inert gas (P-TIG) welding method with Ar-N<sub>2</sub> shielding gas. High cycle fatigue tests of the weld joints were conducted to study the effect of shielding gas nitriding on the fatigue properties. Fatigue tests at three stress levels of 225 MPa, 270 MPa, and 360 MPa were carried out on the weld joints with different N<sub>2</sub> contents, and the fatigue samples were all fractured in the high temperature heat-affected zone (H-HAZ). Within the current process parameters, the fatigue life of the 4 vol.% N<sub>2</sub> welded joints was optimal. Fatigue striations appeared in the fatigue crack propagation zone, and the transient fracture zone was similar to the tensile fracture. Under the low-stress level, the area of the crack propagation zone under 4 vol.% N<sub>2</sub> was the highest, the tear ridges all expanded around the crack source area, and the fatigue crack propagation zone presented a radial distribution. The proliferation and expansion of dislocations were mainly carried out in the austenite grains, and the dislocation density of the fatigue specimens under 4 vol.% N<sub>2</sub> was smaller than that of the Ar specimens. Shielding gas nitriding effectively improved the balance of the two-phase ratio and the hardness of austenite phase, optimized the internal slip system, inhibited the proliferation of dislocations in the austenite phase, and improved the fatigue life of weld joints.https://www.mdpi.com/1996-1944/17/1/109shielding gas nitridingthin-walled pipebutt jointfatigue propertiesP-TIG welding
spellingShingle Chaofei Yang
Wenjian Zheng
Renfu Wang
Jiajia Niu
Lei Sun
Mao Cheng
Xianjing Lu
Zhou Zhou
Jianguo Yang
Study on Fatigue Performance of Pulsed Tungsten Inert Gas Welding Joint of Duplex Stainless Steel Thin Tube
Materials
shielding gas nitriding
thin-walled pipe
butt joint
fatigue properties
P-TIG welding
title Study on Fatigue Performance of Pulsed Tungsten Inert Gas Welding Joint of Duplex Stainless Steel Thin Tube
title_full Study on Fatigue Performance of Pulsed Tungsten Inert Gas Welding Joint of Duplex Stainless Steel Thin Tube
title_fullStr Study on Fatigue Performance of Pulsed Tungsten Inert Gas Welding Joint of Duplex Stainless Steel Thin Tube
title_full_unstemmed Study on Fatigue Performance of Pulsed Tungsten Inert Gas Welding Joint of Duplex Stainless Steel Thin Tube
title_short Study on Fatigue Performance of Pulsed Tungsten Inert Gas Welding Joint of Duplex Stainless Steel Thin Tube
title_sort study on fatigue performance of pulsed tungsten inert gas welding joint of duplex stainless steel thin tube
topic shielding gas nitriding
thin-walled pipe
butt joint
fatigue properties
P-TIG welding
url https://www.mdpi.com/1996-1944/17/1/109
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