scholarly journals An enhancement of the current design concepts for the improved consideration of residual stresses in fatigue-loaded welds

2021 ◽  
Vol 65 (4) ◽  
pp. 643-651
Author(s):  
Th. Nitschke-Pagel ◽  
J. Hensel
Keyword(s):  
Residual Stresses ◽  
State Of The Art ◽  
High Strength Steels ◽  
High Strength ◽  
Design Tools ◽  
Design Concepts ◽  
Treatment Processes ◽  
Real Distribution ◽  
Current Design ◽  
Reliable Knowledge

AbstractThe consideration of residual stresses in fatigue-loaded welds is currently done only qualitatively without reliable knowledge about their real distribution, amount and prefix. Therefore, the tools which enable a more or less unsafe consideration in design concepts are mainly based on unsafe experiences and doubtful assumptions. Since the use of explicitly determined residual stresses outside the welding community is state of the art, the target of the presented paper is to show a practicable way for an enhanced consideration of residual stresses in the current design tools. This is not only limited on residual stresses induced by welding, but also on post-weld treatment processes like HFMI or shot peening. Results of extended experiments with longitudinal fillet welds and butt welds of low and high strength steels evidently show that an improved use of residual stresses in fatigue strength approximation enables a better evaluation of peening processes as well as of material adjusted welding procedures or post-weld stress relief treatments. The concept shows that it is generally possible to overcome the existing extremely conservative but although unsafe rules and regulations and may also enable the improved use of high strength steels.

Butt welded connections of high strength steel

2021 ◽  
Author(s):  
Mareike von Arnim ◽  
Jennifer Spiegler ◽  
Ulrike Kuhlmann
Keyword(s):  
High Strength Steel ◽  
High Performance ◽  
High Strength Steels ◽  
High Strength ◽  
Numerical Investigations ◽  
Design Concepts ◽  
Steel Connections ◽  
Load Carrying ◽  
Current Design ◽  
User Friendly

<p>High-performance materials such as high strength steels allow for resource-efficient innovative structures. Therefore, economical and user-friendly design concepts for welded connections of high strength steels are required. Current design rules had been developed mainly for mild steels, e.g. requiring an overmatching of the filler metal. It is not considered, that a soft area which may form in the heat-affected zone of welded high strength steel connections may lead to an overestimation of the load-carrying capacity. Besides, mixed connections as well as under- and overmatching filler metals are not included in the current design codes. Based on a large number of experimental and numerical investigations, a design concept has been developed which takes the characteristics of butt welded high strength steel connections into account. Additionally, experimental and numerical investigations are planned to transfer the new concept of design also to mixed connections.</p>

Numerical and Experimental Residual Stresses of Different Welded Joint Configurations in Heavy Wall

2020 ◽  
Author(s):  
Chiara Colombo ◽  
Stefano Monti ◽  
Mario Guagliano ◽  
Laura Vergani ◽  
Emanuele Fiordaligi ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Ad Hoc ◽  
High Strength Steels ◽  
High Strength ◽  
Thermal Treatments ◽  
Residual Stress Field ◽  
X Ray ◽  
Finite Element Software ◽  
Asme Code ◽  
Two Parameters

Abstract Refinery equipment subjected to high pressure is commonly made of Vanadium high strength steels (2¼Cr1Mo¼V), characterized by high allowable stress and low toughness in the as welded condition, leading to potential wall cracking before the application of thermal treatments. Therefore, the decision to perform specific thermal treatments after welding is of paramount importance. These thermal treatments, which are quite expensive and time demanding for the manufacturer, are still under discussion and not supported by evident scientific findings. The paper presents a numerical and experimental study on a plate-to-plate weld and on a nozzle-to-plate weld, created as ad-hoc mock-ups. Experimental residual stresses are collected by an X-ray diffractometer in the as welded configurations. These values are used to validate a complex 3D numerical model, implemented with the finite element software Abaqus and its AWI plugin. Finally, this validated model allows for the identification of joint criticality through two parameters: the volume of plasticized material per unit of welded length and the strain-based assessment according with ASME code. Their application as tools to compare the criticality of different welded geometries and the effect of thermal treatments on the residual stress field are discussed.

scholarly journals The Assessment of Selected Properties of Welded Joints in High-Strength Steels

2020 ◽  
pp. 73-79
Author(s):  
Lechosław Tuz
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Welded Joints ◽  
Heat Input ◽  
Structural Changes ◽  
High Strength Steels ◽  
High Strength ◽  
High Quality ◽  
Treatment Processes ◽  
Welding Processes

The use of technologically advanced structural materials entails the necessity of adjusting typical welding processes to special requirements resulting from the limited weldability of certain material groups. Difficulties obtaining high-quality joints may be the consequence of deteriorated mechanical properties and structural changes in materials (beyond requirements of related standards). One of the aforementioned materials is steel characterised by a guaranteed yield point of 1300 MPa, where high strength is obtained through the addition of slight amounts of carbide-forming elements and the application of complex heat treatment processes. A heat input during welding may worsen the aforesaid properties not only in the weld but also in the adjacent material. The tests discussed in the article revealed that the crucial area was that heated below a temperature of 600°C, where the hardness of the material decreased from approximately 520 HV to 330 HV.

Magnetic Properties of Pipeline Steels are Variable

2004 ◽  
Author(s):  
David L. Atherton ◽  
Lynann Clapham
Keyword(s):  
Magnetic Properties ◽  
Yield Strength ◽  
Residual Stresses ◽  
High Strength Steels ◽  
High Strength ◽  
Nondestructive Inspection ◽  
Single Sample ◽  
Pipeline Steels ◽  
Cold Worked ◽  
Inspection Techniques

Magnetic or electromagnetic nondestructive inspection techniques for steel are ultimately limited by the fact that the magnetic properties of high strength steels used in pipelines vary considerably. Different samples of steels with similar mechanical specifications and properties can, and do, have very different magnetic properties. Furthermore large variations often occur over distances of as small as a few millimeters within a single sample depending on position, direction and conditions, particularly applied and residual stresses. Unfortunately these variations are typically most pronounced in high strength steels since these often have high residual stresses as a result of their having been heavily cold worked to enhance yield strength. Here we present examples illustrating the effects of some of these variations.

Residual stresses in strain hardening of high-strength steels

1973 ◽  
Vol 5 (5) ◽  
pp. 600-605
Author(s):  
V. S. Sysoeva ◽  
G. A. Chumak
Keyword(s):  
Residual Stresses ◽  
Strain Hardening ◽  
High Strength Steels ◽  
High Strength

scholarly journals Increasing fatigue performance in AHSS thick sheet by surface treatments

2018 ◽  
Vol 165 ◽  
pp. 22015
Author(s):  
Sergi Parareda ◽  
Antoni Lara ◽  
Henrik Sieurin ◽  
Héber D´Armas ◽  
Daniel Casellas
Keyword(s):  
Surface Roughness ◽  
Fatigue Life ◽  
Residual Stresses ◽  
High Strength Steels ◽  
High Strength ◽  
Fatigue Tests ◽  
Surface Treatments ◽  
Thick Sheet ◽  
Steel Grades ◽  
Mechanical Surface

Advanced High Strength Steels (AHSS) have been widely applied in the automotive industry as an affordable solution for car lightweighting, mainly in parts subjected to crash requirements. Heavy duty vehicle (HDV) can also benefit from the expertise learned in cars, but parts must be designed considering fatigue resistance, especially on trimmed areas, and stiffness. Mechanical surface treatments, as blasting or shot peening, help increasing fatigue life of AHSS in trimmed areas and will allow weight reduction in HDV through gauge downsizing. The expected decrease in stiffness through thickness reduction can be improved by design changes. However, scarce information about the effect of mechanical surface treatments on AHSS are available. Thus, the aim of this work is to evaluate the increment in fatigue life of two different steel grades (350 MPa, and 500MPa of yield strength) in thick sheet by means of mechanical surface treatment – sandblasting. High Cycle Fatigue [HCF] tests were conducted at alternating load [R=-1]. Residual stresses were measured by an X-ray tensometry prior fatigue tests. Also the surface roughness [Rz] and form is measured using an optical non-contact 3D microscope. On the other hand, the fracture surfaces of the test specimens were observed via scanning electron microscope (SEM) in order to determine the crack initiation points. The evaluation of fatigue life in terms of SN curves is also discussed, analysing how the sandblasting process modifies the surface roughness and introduce compressive residual stresses on the external layer of the material. Both phenomena enhance the fatigue strength of the evaluated steel grades.

Energy Efficient Servo Controlled Roll Levelling Machines

2016 ◽  
Vol 716 ◽  
pp. 413-419
Author(s):  
Eneko Sáenz de Argandoña ◽  
Elena Silvestre ◽  
Daniel Garcia ◽  
Joseba Mendiguren ◽  
Lander Galdos
Keyword(s):  
Energy Consumption ◽  
Residual Stresses ◽  
Sheet Metal ◽  
Energy Efficient ◽  
High Strength Steels ◽  
High Strength ◽  
Important Process ◽  
Process Improvements ◽  
Wide Range ◽  
Ultra High Strength Steels

The roll levelling and coil straightening facilities are becoming one of the most important process steps when forming Ultra High Strength Steels. The correct levelling and straightening of these materials are the main responsible for the stabilization of the residual stresses through the thickness and post forming springback of sheet metal formed components.Due to the arrangement of the rolls in roll levellers, micro-sliding occurs between the rolls and the sheet and the first rolls are subjected to high torques and high forces since they are responsible for the plastification of the material to a high extent. In order to reduce these drawbacks and optimize the energy consumption avoiding energy loses due to friction, the use of servo technology in levelling processes is studied in this paper.A wide range of materials are levelled using the conventional and the new servo controlled strategy that uses two servo motors and the process improvements are quantified.

Welding residual stresses in 960 MPa grade QT and TMCP high-strength steels

2017 ◽  
Vol 27 ◽  
pp. 226-232 ◽  
Author(s):  
Thomas Schaupp ◽  
Dirk Schroepfer ◽  
Arne Kromm ◽  
Thomas Kannengiesser
Keyword(s):  
Residual Stresses ◽  
High Strength Steels ◽  
High Strength
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