Blar i NTNU Open på forfatter "Ren, Xiaobo"
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A method for determining material's equivalent stress-strain curve with any axisymmetric notched tensile specimens without Bridgman correction
Tu, Shengwen; Ren, Xiaobo; He, Jianying; Zhang, Zhiliang (Journal article, 2017)Large deformation analyses of problems such as plastic forming, ductile fracture with finite element method need a full range of material's equivalent stress-strain curve or flow stress-strain curve. The equivalent ... -
A new method to estimate the residual stresses in additive manufacturing characterized by point heat source
Sun, Li; Ren, Xiaobo; He, Jianying; Olsen, Jim Stian; Pallaspuro, Sakari; Zhang, Zhiliang (Journal article; Peer reviewed, 2019)Residual stress in additive manufacturing (AM) is one of the key challenges in terms of structural integrity and finish quality of printed components. Estimating the residual stress distribution on additively manufactured ... -
A special notched tensile specimen to determine the flow stress-strain curve of hardening materials without applying the Bridgman correction
Tu, Shengwen; Ren, Xiaobo; Nyhus, Bård; Akselsen, Odd Magne; He, Jianying; Zhang, Zhiliang (Journal article; Peer reviewed, 2017)Structural integrity assessment of weldments requires the input of flow stress-strain curve of each individual material zone. To cope with these challenges, a cylindrical cross weld tensile specimen with a notch located ... -
Additive manufacture of superduplex stainless steel using WAAM
Eriksson, Magnus Carl Fredrik; Lervåg, Malin; Sørensen, Camilla; Robertstad, Andreas; Brønstad, Bård M.; Nyhus, Bård; Aune, Ragnhild; Ren, Xiaobo; Akselsen, Odd Magne (Journal article; Peer reviewed, 2018)Superduplex stainless steels have been used in the oil and gas industry for a couple of decades due to the combination of excellent mechanical properties and corrosion resistance. The present investigation addresses the ... -
Additive Manufacturing with Superduplex Stainless Steel Wire by CMT Process
Lervåg, Malin; Sørensen, Camilla; Robertstad, Andreas; Brønstad, Bård M.; Nyhus, Bård; Eriksson, Magnus Carl Fredrik; Aune, Ragnhild; Ren, Xiaobo; Akselsen, Odd Magne; Bunaziv, Ivan (Journal article; Peer reviewed, 2020)For many years, the oil and gas industry has utilized superduplex stainless steels due to their high strength and excellent corrosion resistance. Wire arc additive manufacturing (WAAM) was used with superduplex filler wire ... -
A bead sequence-driven deposition pattern evaluation criterion for lowering residual stresses in additive manufacturing
Sun, Li; Ren, Xiaobo; He, Jianying; Zhang, Zhiliang (Peer reviewed; Journal article, 2021)Deposition patterns can significantly influence the distribution and magnitude of residual stress in additively manufactured parts. Time-consuming thermal-mechanical simulations and costly experimental studies are often ... -
CAFE based Multi-scale Modelling of Ductile-to-Brittle Transition of Steel with a Temperature Dependent Effective Surface Energy
Li, Yang; Shterenlikht, Anton; Ren, Xiaobo; He, Jianying; Zhang, Zhiliang (Journal article; Peer reviewed, 2019)It is still a challenge to numerically achieve the interactive competition between ductile damage and brittle fracture in ductile-to-brittle transition (DBT) region. In addition, since two types of fracture occur at two ... -
Constraint effect on the brittle-to-ductile transition of single-crystal iron induced by dislocation mobility
Li, Yang; Ren, Xiaobo; He, Jianying; Zhang, Zhiliang (Journal article, 2018)The brittle-to-ductile transition (BDT), no matter what the dominated mechanism is, dislocation nucleation or dislocation motion, is not an intrinsic phenomenon of material, and depends not only on the strain rate but also ... -
Determining critical CTOA from energy-load curves with DWTT specimen
Shuai, Jian; Tu, Shengwen; Wang, Junqiang; Ren, Xiaobo; He, Jianying; Zhang, Zhiliang (Journal article; Peer reviewed, 2017)Running ductile fracture is one of the most catastrophic accidents of pipelines for natural gas transportation. Crack arrest toughness is important for preventing crack extension to a long distance along pipeline. Critical ... -
Determining the tensile properties of Arctic materials and modelling their effects on fracture
Tu, Shengwen (Doctoral theses at NTNU;2018:269, Doctoral thesis, 2018)The fracture behavior of metallic materials at low temperatures arise great attention among the petroleum industries, due to the potential considerable amount of petroleum and gas resources to be found there. Deep understanding ... -
Effect of heat input on nanomechanical properties of wire-arc additive manufactured Al 4047 alloys
Liu, Siqi; Wan, Di; Peng, Ding; Lu, Xu; Ren, Xiaobo; Fu, Yuequn; Wang, Feng; Li, Yanjun; Zhang, Zhiliang; He, Jianying (Peer reviewed; Journal article, 2022)Heat input is one of the most important process parameters during additive manufacturing (AM). It is of great significance to understand the effect of heat input on the microstructure and nanomechanical properties, as well ... -
Effect of low temperature tensile properties on crack driving force for Arctic applications
Dahl, Bjørn Augdal; Ren, Xiaobo; Akselsen, Odd Magne; Nyhus, Bård; Zhang, Zhiliang (Journal article; Peer reviewed, 2017)Many petroleum companies expand their activities further north towards the Arctic region, resulting in design temperatures down to −60 °C, which is much lower than what is usual for most current petroleum installations. ... -
Effect of preheating and preplaced filler wire on microstructure and toughness in laser-arc hybrid welding of thick steel
Bunaziv, Ivan; Langelandsvik, Geir; Ren, Xiaobo; Westermann, Ida; Rørvik, Gisle; Dørum, Cato; Danielsen, Morten Høgseth; Eriksson, Magnus Carl Fredrik (Peer reviewed; Journal article, 2022)Acicular ferrite (AF) is the most important microstructural constituent to achieve high toughness at low temperatures in weld metal of steels. This is due to the relatively small grain size and large misorientation angles. ... -
Effect of Sigma Phase in Wire Arc Additive Manufacturing of Superduplex Stainless Steel
Akselsen, Odd Magne; Bjørge, Ruben; Ånes, Håkon Wiik; Ren, Xiaobo; Nyhus, Bård (Peer reviewed; Journal article, 2021)In the present study, the thermal program in wire and arc additive manufacturing has been varied in terms of heat input and interpass temperature. Three walls were completed with subsequent Charpy V impact toughness and ... -
Effect of the Lüders plateau on ductile fracture with MBL model
Tu, Shengwen; Ren, Xiaobo; He, Jianying; Zhang, Zhiliang (Journal article; Peer reviewed, 2019)In this study, the effect of Lüders plateau on the ductile crack growth resistance has been investigated with the Gurson damage model and the modified boundary layer (MBL) model, under mode I plane strain condition. The ... -
The Effect of Thermal Residual Stresses on Ductile-to-Brittle Transition of a Welded TMCR Steel by Using CAFE Method
Li, Yang; Ren, Xiaobo; He, Jianying; Zhang, Zhiliang (Peer reviewed; Journal article, 2019)The effect of residual stress on fracture of materials or structures has been widely studied. However, its influence on ductile-to-brittle transition (DBT), a crucial phenomenon of structural materials, has rarely been ... -
Effect of welding residual stresson fracture
Ren, Xiaobo (Doktoravhandlinger ved NTNU, 1503-8181; 2010:77, Doctoral thesis, 2010)Residual stresses are unavoidable in welded constructions. How to correctly predict residual stresses and assess their effect on structural integrity is a fundamental issue. One of the most difficult aspects in structural ... -
Experimental measurement of temperature-dependent equivalent stress-strain curves of a 420 MPa structural steel with axisymmetric notched tensile specimens
Tu, Shengwen; Ren, Xiaobo; He, Jianying; Zhang, Zhiliang (Journal article; Peer reviewed, 2019)Recently, the authors in this paper proposed a correction function to determine material’s equivalent stress-strain curve with axisymmetric-notched tensile specimens. In this study, tensile tests were performed at room ... -
Fiber Laser-MAG Hybrid Welding of Structural Steels for Arctic Applications
Bunaziv, Ivan (Doctoral theses at NTNU;2018:149, Doctoral thesis, 2018) -
Filler metal distribution and processing stability in laser-arc hybrid welding of thick HSLA steel
Bunaziv, Ivan; Wenner, Sigurd; Ren, Xiaobo; Frostevarg, Jan; Kaplan, Alexander F.H.; Akselsen, Odd Magne (Journal article; Peer reviewed, 2020)Welds made by high power laser beam have deep and narrow geometry. Addition offiller wire by the arc source,forming the laser-arc hybrid welding (LAHW) process, is very important to obtain required mechanical prop-erties. ...