scholarly journals A Fracture Mechanics-Based Optimal Fatigue Design Method of Under-Matched HSLA Steel Butt-Welded Joints with Imperfections

2019 ◽  
Vol 9 (17) ◽  
pp. 3609 ◽  
Author(s):  
Wen ◽  
Wang ◽  
Dong ◽  
Fang
Keyword(s):  
Fracture Mechanics ◽  
Welded Joints ◽  
Design Method ◽  
Hsla Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Engineering Structures ◽  
Fatigue Design ◽  
Load Carrying ◽  
Practical Engineering

The trend of light-weight structures leads to the wide application of high strength steels in engineering structures. When welding high strength steels, under-matched consumables could reduce the cold-cracking tendency, simplifying the preheating process. However, under-matched welds would sometimes make the high strength base metal pointless due to its weak load-carrying capacity. For the purpose of enhancing the fatigue strength of under-matched welded joints, a fracture mechanics-based optimal fatigue design method of under-matched butt-welded joints is proposed in this work. Heterogeneous mechanical features of welded joints, which are not considered in current standards and codes, are incorporated into the optimal design method. The fatigue limit of the high strength parent metal is taken as the design target, which has seldom been reported. HSLA steel Q550, with its under-matched consumable ER70S-6 composed X-shaped butt-welds, is selected for experimental verification. The experimental results indicate that the fracture mechanic based equal-fatigue-bearing-capacity (EFBC) design method established in this work is feasible and could be a valuable reference for the design of practical engineering structures.

scholarly journals Nominal Stress-Based Equal-Fatigue-Bearing-Capacity Design of under-matched HSLA Steel Butt-welded Joints

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 880 ◽  
Author(s):  
Xue Wen ◽  
Ping Wang ◽  
Zhibo Dong ◽  
Yong Liu ◽  
Hongyuan Fang
Keyword(s):  
Bearing Capacity ◽  
Fatigue Limit ◽  
Base Metal ◽  
Welded Joints ◽  
Design Method ◽  
Hsla Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Nominal Stress ◽  
Load Carrying

Under-matched welds could minimize the tendency of cold cracking and reduce the preheating operations when high strength steels are welded. However, its low load-carrying capacity might make the high strength parent metal meaningless. With the aim of improving the fatigue limit of under-matched butt-welded joints, this work establishes a nominal stress based fatigue design method for under-matched butt welds while considering its heterogeneous mechanical features. The fatigue life of the base metal is set to be the design goal for the under-matched butt-welded joints, which has scarce been tried before. An equal-fatigue-bearing capacity (EFBC) design method fit for the under-matched butt-welded joints is thus applied with the aims of equal fatigue limit of base metal. X-shaped butt-welded joint is selected to carry out experimental verification where HSLA steel Q550 as the base metal and ER70S-6 as the under-matched filler metal are used. The results show that the EFBC method proposed here is feasible. Note that the EFBC method is valid only in high cycle fatigue.

scholarly journals Imperfections and Modelling of the Weld Bead Profile of Laser Butt Joints in HSLA Steel Thin Plate

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 151
Author(s):  
Patricio G. Riofrío ◽  
José A. M. Ferreira ◽  
Carlos A. Capela
Keyword(s):  
Laser Welding ◽  
Welded Joints ◽  
Hsla Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Weld Bead ◽  
Welding Parameters ◽  
Great Decrease ◽  
Weld Quality ◽  
Butt Joints

In many applications that use high strength steels, structural integrity depends greatly on weld quality. Imperfections and the weld bead geometry are influencing factors on mechanical properties of the welded joints but, especially in the fatigue strength, they cause a great decrease. The proper knowledge of these two factors is important from the nominal stress approach to the fracture mechanics approaches. Studies concerning the profile and imperfections of the weld bead in laser welding for thin plates of high strength steels are scarce. In this work, these two aspects are covered for five series single and double-welded joints, butt joints in a 3 mm thick HSLA steel, welded in a small range of welding parameters. The actual profiles captured with profilometer were modeled with proposed geometric parameters achieving an adequate fit with values of the coefficient of determination ℜ2 greater than 0.9000. Description of imperfections includes the distributions of porosity and undercuts. The evaluation of the weld quality, taking as guide the ISO 13919-1 standard determined B and D levels for the welded series while based on the stress-concentrating effect, showed a greater detriment in those series with undercuts and excessive penetration. The analysis of variance validated the results of the different combinations of laser welding parameters and showed, for the factorial experimental design, a more significant effect of the welding speed.

scholarly journals Nominal stress based equal fatigue bearing capacity design of HSLA steel V-shaped butt-welded joints

2018 ◽  
Vol 221 ◽  
pp. 01009
Author(s):  
Wen Xue ◽  
Ping Wang ◽  
Zhibo Dong ◽  
Hongyuan Fang
Keyword(s):  
Bearing Capacity ◽  
Welded Joints ◽  
Design Method ◽  
Hsla Steel ◽  
Estimation Method ◽  
High Strength ◽  
Nominal Stress ◽  
Fatigue Load ◽  
Capacity Design ◽  
Fatigue Life Estimation

Based on nominal stress, this paper proposed a fatigue life estimation method of V-shaped butt welded joints. Then, the fatigue bearing capacity of the base metal under the same fatigue load was used as design goal of the V-shaped butt welded joints and an equal fatigue bearing capacity (EFBC) design method for V-shaped butt welds was thus formed. High strength low alloy steel Q690 was chosen as the experimental material to carry out the equal fatigue bearing capacity design.

Load Carrying Capacities of Butt Welded Joints in High Strength Steels

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
M. Khurshid ◽  
Z. Barsoum ◽  
I. Barsoum
Keyword(s):  
Weld Metal ◽  
Carrying Capacity ◽  
Welded Joints ◽  
High Strength Steels ◽  
High Strength ◽  
Filler Material ◽  
Filler Materials ◽  
Load Carrying Capacity ◽  
Design Rules ◽  
Load Carrying

The aim of this study is to investigate the influence of yield strength of the filler material and weld metal penetration on the load carrying capacity of butt welded joints in high-strength steels (HSS) (i.e., grade S700 and S960). These joints are manufactured with three different filler materials (under-matching, matching, and over-matching) and full and partial weld metal penetrations. The load carrying capacities of these mentioned joints are evaluated with experiments and compared with the estimations by finite element analysis (FEA), and design rules in Eurocode3 and American Welding Society Code AWS D1.1. The results show that load carrying estimations by FEA, Eurocode3, and AWS D1.1 are in good agreement with the experiments. It is observed that the global load carrying capacity and ductility of the joints are affected by weld metal penetration and yield strengths of the base and filler materials. This influence is more pronounced in joints in S960 steel welded with under-matched filler material. Furthermore, the base plate material strength can be utilized in under-matched butt welded joints provided appropriate weld metal penetration and width is assured. Moreover, it is also found that the design rules in Eurocode3 (valid for design of welded joints in steels of grade up to S700) can be extended to designing of welds in S960 steels by the use of correlation factor of one.

ECA Methodology for Fatigue Design of Risers and Flowlines

2007 ◽  
Author(s):  
C. H. Luk ◽  
T. J. Wang
Keyword(s):  
Fracture Mechanics ◽  
Design Method ◽  
Steel Catenary Riser ◽  
Fatigue Design ◽  
Wide Range ◽  
Fatigue And Fracture ◽  
Level 3 ◽  
Fatigue Loads ◽  
Vessel Motion ◽  
Level 2

Engineering Criticality Assessment (ECA) is a procedure based on fracture mechanics that may be used to supplement the traditional S-N approach and determine the flaw acceptance and inspection criteria in fatigue and fracture design of risers and flowlines. A number of design codes provide guidance for this procedure, e.g. BS-7910:2005 [1]. However, more investigations and example studies are still needed to address the design implications for riser and flowline applications. This paper provides a review of the existing ECA methodology, presents a fracture mechanics design method for a wide range of riser and flowline fatigue problems, and shows flaw size results from steel catenary riser (SCR) and flowline (FL) examples. The first example is a deepwater SCR subjected to fatigue loads due to vessel motion and riser VIV. The second example is a subsea flowline subjected to thermal fatigue loads. The effects of crack re-characterization and material plasticity on the Level-2 and Level-3 ECA results of the SCR and flowline examples are illustrated.

Investigation of Structural and Material Effects on Crashworthiness of Advanced High Strength Steel Columns

2003 ◽  
Author(s):  
Faycal Ben-Yahia ◽  
James A. Nemes ◽  
Farid Hassani
Keyword(s):  
Numerical Study ◽  
Hsla Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Column Height ◽  
Steel Columns ◽  
Advanced High Strength Steels ◽  
Element Simulation ◽  
Formed Channel ◽  
Good Agreement

An experimental and numerical study was performed to evaluate the crashworthiness of several advanced high strength steels. The behavior of two Dual Phase (DP) steels and an HSLA steel are compared by examining the crush response of longeron column specimens, experimentally and computationally. The closed section columns, fabricated by spot welding formed channel sections, in both single hat and double hat configurations were exposed to 182 kg and 454 kg axial impacts at different velocities. Final column height and impact force history were recorded and compared with results of finite element simulation of the columns. Good agreement was found between experiments and computations.

scholarly journals Numerical analyses on welded joints at high‐strength steels

ce/papers ◽  
2019 ◽  
Vol 3 (3-4) ◽  
pp. 725-730
Author(s):  
Richard Stroetmann ◽  
Thoralf Kästner
Keyword(s):  
Welded Joints ◽  
High Strength Steels ◽  
High Strength ◽  
Numerical Analyses

Some Fracture Mechanics Correlations

1968 ◽  
Vol 10 (4) ◽  
pp. 329-336
Author(s):  
L. P. Pook
Keyword(s):  
Mechanical Properties ◽  
Fracture Mechanics ◽  
Tensile Test ◽  
High Strength Steels ◽  
High Strength ◽  
Gauge Length ◽  
Published Data ◽  
Square Root ◽  
Beryllium Copper ◽  
Reduction Of Area

The results of tests on two high-strength steels, beryllium copper and perspex, together with some published data on high-strength steels were examined to see whether there was any relationship between the fracture mechanics parameter K1C and conventional mechanical properties. It was found that for steels and beryllium copper a correlation appeared to exist between K1C and the zero gauge length strain (= Z/(1 - Z) where Z is the reduction of area measured in a tensile test). It was also found that for constant, K1C was proportional to the square root of Young's modulus. The correlation band for steels was too wide for K1C to be estimated accurately from.

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