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Leif Karlsson

Professor

Anställd på Avdelningen för svetsteknologi.

Forskar inom området teknik, produktionsteknik.


Forskningsområde/forskningsintresse

Det huvudsakliga intresset ligger inom svetsteknologi, speciellt med inriktning mot svetsmetallurgi. Målet är att förstå, förutsäga och kontrollera sambanden mellan, å ena sidan, svetsens sammansättning, svetsprocessen och svetsproceduren och, å andra sidan, svetsens mikrostruktur och egenskaper.

Undervisning/handledning

Jag handleder doktorander som studerar utmattning av svetsade komponenter, svetsning av super duplexa stål, svetsning av "nya" material för fordonstillämpningar och värmebehandling av verktygsstål. Jag undervisar bland annat i kursen "Svetsteknologi" på Högskolan Väst.

Nyckelord

Svetsteknologi, fogningsmetoder, höghållfasta stål, duplexa rostfria stål, verktygsstål.


Publikationer


A New Approach to the Study of Multi-Pass Welds–Microstructure and Properties of Welded 20-mm-Thick Superduplex Stainless Steel

Publicerat

A New Approach to the Study of Multi-Pass Welds–Microstructure and Properties of Welded 20-mm-Thick Superduplex Stainless Steel

Type 2507 superduplex stainless steel 20 mm in thickness was multi-pass-welded with Gas Metal Arc Welding (GMAW) and Flux-Cored Arc Welding (FCAW)...

Ferrite content measurement in super duplex stainless steel welds

Publicerat

Ferrite content measurement in super duplex stainless steel welds

Approaches to determining ferrite fraction (%) and ferrite number (FN) were examined for super duplex stainless steel (SDSS) welds. A reference...

Low Porosity in Cast Magnesium Welds by Advanced Laser Twin-Spot Welding

Publicerat

Low Porosity in Cast Magnesium Welds by Advanced Laser Twin-Spot Welding

Porosity is reported to be a major issue when welding cast magnesium. Therefore, it is important to understand the pore formation mechanisms and fi...

Physical and kinetic simulation of nitrogen loss in high temperature heat affected zone of duplex stainless steels

Publicerat

Physical and kinetic simulation of nitrogen loss in high temperature heat affected zone of duplex stainless steels

High temperature heat affected zone (HTHAZ) of duplex stainless steels is prone to local corrosion attack due to a high ferrite fraction and nitrid...

Wire-arc additive manufacturing of a duplex stainless steel : thermal cycle analysis and microstructure characterization

Publicerat

Wire-arc additive manufacturing of a duplex stainless steel : thermal cycle analysis and microstructure characterization

The evolution of microstructures with thermal cycles was studied for wire-arc additive manufacturing of duplex stainless steel blocks. To produce...

Correction to : Time-temperature-precipitation and property diagrams for super duplex stainless steel weld metals (Welding in the World, (2018), 62, 3, (517-533), 10.1007/s40194-018-0548-z)

Publicerat

Correction to : Time-temperature-precipitation and property diagrams for super duplex stainless steel weld metals (Welding in the World, (2018), 62, 3, (517-533), 10.1007/s40194-018-0548-z)

Unfortunately due to typesetting mistakes, Tables 4-€“6 have been displayed erroneously in the article. © 2018, International Institute of Welding.

Effect of Laser Welding Parameters on Porosity of Weldsin Cast Magnesium Alloy AM50

Publicerat

Effect of Laser Welding Parameters on Porosity of Weldsin Cast Magnesium Alloy AM50

Pores in the weld metal lower the mechanical properties of the weld. It is therefore important to understand the pore formation mechanisms and find...

Effect of sigma phase morphology on the degradation of properties in a super duplex stainless steel

Publicerat

Effect of sigma phase morphology on the degradation of properties in a super duplex stainless steel

Sigma phase is commonly considered to be the most deleterious secondary phase precipitating in duplex stainless steels, as it results in an extreme...

Microstructure and functionality of a uniquely graded super duplex stainless steel designed by a novel arc heat treatment method

Publicerat

Microstructure and functionality of a uniquely graded super duplex stainless steel designed by a novel arc heat treatment method

A novel arc heat treatment technique was applied to design a uniquely graded super duplex stainless steel (SDSS), by subjecting a single sample to ...

Spinodal Decomposition in Functionally Graded Super Duplex Stainless Steel and Weld Metal

Publicerat

Spinodal Decomposition in Functionally Graded Super Duplex Stainless Steel and Weld Metal

Low-temperature phase separations (T < 500 °C), resulting in changes in mechanical and corrosion properties, of super duplex stainless steel (SDSS)...

Time-temperature-precipitation and property diagrams for super duplex stainless steel weld metals

Publicerat

Time-temperature-precipitation and property diagrams for super duplex stainless steel weld metals

Super duplex stainless steel (SDSS) weld metal microstructures, covering the complete temperature range from ambient to liquidus, were produced by...

A novel arc heat treatment technique for producing graded microstructures through controlled temperature gradients

Publicerat

A novel arc heat treatment technique for producing graded microstructures through controlled temperature gradients

This paper introduces a novel arc heat treatment technique to produce samples with graded microstructures through the application of controlled...

Applicability of Low Transformation Temperature welding consumables to increase fatigue strength of welded high strength steels

Publicerat

Applicability of Low Transformation Temperature welding consumables to increase fatigue strength of welded high strength steels

Application of Low Transformation Temperature (LTT) consumables in welding is a recent approach to increase the fatigue strength of welds. In this...

Correlation between laser welding sequence and distortions for thin sheet structures

Publicerat

Correlation between laser welding sequence and distortions for thin sheet structures

Thin ultra-high strength steel shaped as 700 mm long U-beams have been laser welded in overlap configuration to study the influence of welding...

Effect of multipass TIG welding on the corrosion resistance and microstructure of a super duplex stainless steel

Publicerat

Effect of multipass TIG welding on the corrosion resistance and microstructure of a super duplex stainless steel

This is a study of the effect of repetitive TIG (tungsten inert gas) welding passes, melting and remelting the same material volume on microstructu...

Improving fatigue strength of welded 1300 MPa yield strength steel using HFMI treatment or LTT fillers

Publicerat

Improving fatigue strength of welded 1300 MPa yield strength steel using HFMI treatment or LTT fillers

Fatigue improvement techniques are widely used to increase fatigue strength of welded high strength steels. In this paper high frequency mechanical...

Metallurgical effects and distortions in laser welding of thin sheet steels with variations in strength

Publicerat

Metallurgical effects and distortions in laser welding of thin sheet steels with variations in strength

Geometrical distortions occur while welding, but the understanding of how and why they occur and how to control them is limited. The relation betwe...

Neutron Diffraction Evaluation of Near Surface Residual Stresses at Welds in 1300 MPa Yield Strength Steel

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Neutron Diffraction Evaluation of Near Surface Residual Stresses at Welds in 1300 MPa Yield Strength Steel

Evaluation of residual stress in the weld toe region is of critical importance. In this paper, the residual stress distribution both near the surfa...

Retained Austenite Transformation during Heat Treatment of a 5 Wt Pct Cr Cold Work Tool Steel

Publicerat

Retained Austenite Transformation during Heat Treatment of a 5 Wt Pct Cr Cold Work Tool Steel

Retained austenite transformation was studied for a 5 wt pct Cr cold work tool steel tempered at 798 K and 873 K (525 degrees C and 600 degrees C)...

Effect of Austenitization and Tempering on the Microstructure and Mechanical Properties of a 5 wt% Cr Cold Work Tool Steel

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Effect of Austenitization and Tempering on the Microstructure and Mechanical Properties of a 5 wt% Cr Cold Work Tool Steel

The effects of austenitization and tempering temperatures for a 5 wt% Cr cold work tool steel are studied with an aim of understanding the influenc...

Effect of HFMI treatment procedure on weld toe geometry and fatigue properties of high strength steel welds

Publicerat

Effect of HFMI treatment procedure on weld toe geometry and fatigue properties of high strength steel welds

The effects of high frequency mechanical impact (HFMI) treatment procedure on the weld toe geometry and fatigue strength in 1300 MPa yield strength...

Effect of high frequency mechanical impact treatment on fatigue strength of welded 1300 MPa yield strength steel

Publicerat

Effect of high frequency mechanical impact treatment on fatigue strength of welded 1300 MPa yield strength steel

High frequency mechanical impact (HFMI) is a recent post weld treatment method which can be employed to increase the fatigue strength of welded...

Effects of Austenitisation Temperature and Multiple Tempering on the Microstructure and Impact Toughness of a 5 wt. % Cr Cold Work Tool Steel

Publicerat

Effects of Austenitisation Temperature and Multiple Tempering on the Microstructure and Impact Toughness of a 5 wt. % Cr Cold Work Tool Steel

The microstructure and properties of a 5 wt.% Cr cold work tool steel were studied after austenitisation at 1020°C, 1050°C or 1075°C followed by...

Influence of multiple thermal cycles on microstructure of heat-affected zone in TIG-welded super duplex stainless steel

Publicerat

Influence of multiple thermal cycles on microstructure of heat-affected zone in TIG-welded super duplex stainless steel

The influence of heat input and multiple welding cycles on the microstructure of the heat-affected zone in autogenously TIG-welded 6 mm 2507 type...

Influenza del gas di protezione sul comportamento e le proprietà  di giunti sa dati di acciai duplex e superduplex : Effect of shielding gas on welding performance and properties of duplex and superduplex stainless steel welds

Publicerat

Influenza del gas di protezione sul comportamento e le proprietà  di giunti sa dati di acciai duplex e superduplex : Effect of shielding gas on welding performance and properties of duplex and superduplex stainless steel welds

The influence of shielding gases on welding performance and on properties of duplex and superduplex stainless steel welds was studied. Using argon ...

Monitoring Thermal Cycles in Multi-pass Welding

Publicerat

Monitoring Thermal Cycles in Multi-pass Welding

Differently from any previous investigation in welding, this research work presents a novel development that allows temperature to be measured and...

Nitrogen loss and effects on microstructure in multipass TIG welding of a super duplex stainless steel

Publicerat

Nitrogen loss and effects on microstructure in multipass TIG welding of a super duplex stainless steel

Nitrogen loss is an important phenomenon in welding of super duplex stainless steels. In this study, a super duplex stainless steel was autogenousl...

Effect of shielding gas on welding performance and properties of duplex and superduplex stainless steel welds

Publicerat

Effect of shielding gas on welding performance and properties of duplex and superduplex stainless steel welds

The influence of shielding gases on welding performanceand on properties of duplex and superduplex stainlesssteel welds was studied. Using argon as...

Effect of welding position on properties of duplex and superduplex stainless steel circumferential welds

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Effect of welding position on properties of duplex and superduplex stainless steel circumferential welds

The influence of welding position on properties ofduplex and superduplex stainless steel welds was studied. Circumferential pipe welds were produce...

Multipass Autogenous TIG Welding of Super Duplex Stainless

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Multipass Autogenous TIG Welding of Super Duplex Stainless

Multipass welding of super duplex stainless steels (SDSS) needs further characterization due to their growing applications inpetrochemical and...

Neutron Diffraction Studies of Residual Stress Distribution in the Vicinity of the Single Pass Fillet Steel Welds

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Neutron Diffraction Studies of Residual Stress Distribution in the Vicinity of the Single Pass Fillet Steel Welds

In this contribution the results of residual strain/stress measurements performed on several single pass fillet steel welds, which were carried out...

Productivity Aspects in Submerged Arc Welding of Thick High-Strength Steels

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Productivity Aspects in Submerged Arc Welding of Thick High-Strength Steels

A series of welding tests were made on 35 mm thick F500W high strength steel. This specific steel grade is developed for use in arctic conditions,...

Strength and Impact Toughness of High Strength Steel Weld Metals : Influence of Welding Method, Dilution and Cooling Rate

Publicerat

Strength and Impact Toughness of High Strength Steel Weld Metals : Influence of Welding Method, Dilution and Cooling Rate

Producing welds with properties matching those of the steel is a challenge at high strength levels. The present study has investigated how the choi...

Submerged Arc Welding of High Strength Steel for Shipbuilding Applications

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Submerged Arc Welding of High Strength Steel for Shipbuilding Applications

In most cases primary purpose for use of high strength steels is weight reduction with resulting benefits in product lifecycle costs. However, as t...

The relative effects of residual stresses and weld toe geometry on fatigue life of weldments

Publicerat

The relative effects of residual stresses and weld toe geometry on fatigue life of weldments

The weld toe is one of the most probable fatigue crack initiation sites in welded components. In this paper, the relative influences of residual...

Towards a Map of Solidification Cracking Risk in Laser Welding of Austenitic Stainless Steels

Publicerat

Towards a Map of Solidification Cracking Risk in Laser Welding of Austenitic Stainless Steels

In this work, two series of specimens with Hammar and Svensson's Cr- and Ni-equivalents (Creq+Nieq) = 35 and 45 wt% were used to cover a wide range...

Welding enabling light weight design of heavy vehicle chassis

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Welding enabling light weight design of heavy vehicle chassis

Development of lightweight cars for saving fuel and reducing emission has been a priority for more than a decade. A similar trend is now seen for...

Distortion Analysis in Laser Welding of Ultra High Strength Steel

Publicerat

Distortion Analysis in Laser Welding of Ultra High Strength Steel

Due to increased demands on reduced weight in automotive industries, the use of ultra high strength steels (UHSS) has increased. When laser welding...

Effect of interpass temperature on residual stresses in multipass welds produced using low transformation temperature filler alloy

Publicerat

Effect of interpass temperature on residual stresses in multipass welds produced using low transformation temperature filler alloy

Weld filler alloys that exploit transformation plasticity through low austenite to martensite transformation temperatures offer an effective method...

Effects of dilution and baseplate strength on stress distributions in multipass welds deposited using low transformation temperature filler alloys

Publicerat

Effects of dilution and baseplate strength on stress distributions in multipass welds deposited using low transformation temperature filler alloys

Transformation plasticity can be utilised to control residual stresses in steel welds. This requires special filler alloys that transform at a...

Efficient welding of high strength steel

Publicerat

Efficient welding of high strength steel

 Producing welds with properties matching those of the steel is a challenge at high strength levels. The present study investigated how cooling rat...

Identification of Weld Residual Stresses Using Diffraction Methods andtheir Effect on Fatigue Strength of High Strength Steels Welds

Publicerat

Identification of Weld Residual Stresses Using Diffraction Methods andtheir Effect on Fatigue Strength of High Strength Steels Welds

It is well known that fatigue strength of welded joints does not depend on steel strength. Better fatigue strength of welded joints, e.g. longer li...

Influence of dilution on properties of high strength steel weld metals

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Influence of dilution on properties of high strength steel weld metals

Non-destructive measurement of weld toe radius using Weld Impression Analysis, Laser Scanning Profiling and Structured Light Projection methods

Publicerat

Non-destructive measurement of weld toe radius using Weld Impression Analysis, Laser Scanning Profiling and Structured Light Projection methods

Optimising Quality and Productivity in Welding of Duplex and Superduplex Stainless Steels

Publicerat

Optimising Quality and Productivity in Welding of Duplex and Superduplex Stainless Steels

The aim of this work was to study the influence of shielding gases and welding positions on properties of duplex and superduplex stainless steel...

Orientation relationships of intragranular austenite in duplex stainless steel weld metals

Publicerat

Orientation relationships of intragranular austenite in duplex stainless steel weld metals

Formation and characteristics of fine intragranular austenite were studied for low energy input duplex stainless steel welds. Microstructures were...

Residual stress distribution measurement by neutron diffraction of the single pass fillet steel welds

Publicerat

Residual stress distribution measurement by neutron diffraction of the single pass fillet steel welds

In this contribution the results of residual strain/stress measurements performed on several single pass fillet steel welds which were carried out ...

Residual stress distributions at high strength steel welds prepared by low transformation temperature (LTT) and conventional welding consumables

Publicerat

Residual stress distributions at high strength steel welds prepared by low transformation temperature (LTT) and conventional welding consumables

Residual stress distributions in fillet welds in 8 mm 900 MPa steel have been mapped perpendicular and parallel to the weld line and also through t...

Surface residual stresses in multipass welds produced using low transformation temperature filler alloys

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Surface residual stresses in multipass welds produced using low transformation temperature filler alloys

Tensile residual stresses at the surface of welded components are known to compromise fatigue resistance through the accelerated initiation of...

The measurement of weld toe radius using three non-destructive techniques

Publicerat

The measurement of weld toe radius using three non-destructive techniques

The three non-destructive methods Weld Impression Analysis, Laser Scanning Profiling and Structured Light Projection were employed to measure...

Forskningsprojekt