Effect of forced cooling after welding on CGHAZ mechanical properties of a martensitic steel

Laitila, Juhani; Larkiola, Jari; Porter, David

doi:10.1007/s40194-018-0617-3

Cited by 5 publications

(8 citation statements)

References 18 publications

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“…Mean yield strength increased 9.1% with a p value of 0.00018 when external cooling was used. The increase in yield and tensile strength was in line with previous findings made by the authors on the CGHAZ of a 960-MPa steel in which the yield and tensile strength of the CGHAZ increased when the steel was cooled down to 100°C with cooling rate of 15°C/s [16] (Fig. 9).…”

Section: Strengthsupporting

confidence: 92%

“…From a productivity point of view, therefore, it would be beneficial to apply external cooling to reduce t he waiting time as much as possi ble. Furthermore, previous research by the present authors conducted on the CGHAZ of two different steels with yield strengths of 700 and 960 MPa has shown that mechanical properties are strongly affected by the cooling rate below 500°C [15,16]. It was discovered that cooling the weld rapidly all the way to 100°C produced better mechanical property combinations than rapid cooling to 500, 400, 300, or 200°C followed by free cooling in air.…”

Section: Introductionmentioning

confidence: 51%

“…It was discovered that cooling the weld rapidly all the way to 100°C produced better mechanical property combinations than rapid cooling to 500, 400, 300, or 200°C followed by free cooling in air. Depending on the steel studied, tensile strength, yield strength, elongation to fracture, and impact toughness either increased or remained unaffected when forced cooling at 15°C/s to 100°C rather than higher temperatures or completely free cooling [15,16]. However, the effect of forced cooling depends on the steel chemistry involved, for example, in one previous study conducted by Hoy et al demonstrated that six different low-carbon steels became brittle at low temperatures (− 40°C) when they were cooled rapidly to temperatures below 300°C [17], meaning that those steels cannot be cooled rapidly if they are to be used in cold environments.…”

Section: Introductionmentioning

confidence: 99%

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Effect of enhanced cooling on mechanical properties of a multipass welded martensitic steel

Laitila

Larkiola

2019

Weld World

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The effect of forced cooling using heat sinks on the mechanical properties and interpass waiting time of two-pass welds has been studied for a martensitic steel with a yield strength of 960 MPa when the interpass temperature was 100°C. Cross-weld tensile and − 40°C Charpy-V impact toughness properties were examined. The use of heat sinks is shown to result in a beneficial increase of the cross-weld yield strength but at the expense of the yield-to-tensile strength ratio. Due to its particularly detrimental effect on the heat-affected zone (HAZ) toughness of multipass welds, special attention was given in the Charpy-V toughness of the intercritically reheated coarse-grained HAZ (ICCGHAZ) by also testing simulated ICCGHAZs. It is shown that forced cooling has a beneficial effect in respect of the toughness of this simulated subzone and on the Charpy-V toughness of the HAZ of the actual welds. The interpass cooling time during the two-pass welding was reduced by 37%. The results indicate that, in the case of high-strength steels, it may be possible to simultaneously improve both welding productivity and mechanical properties by using forced cooling down to 100°C to reduce waiting time between weld passes.

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Section: Strengthsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 51%

Section: Introductionmentioning

confidence: 99%

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Effect of enhanced cooling on mechanical properties of a multipass welded martensitic steel

Laitila

Larkiola

2019

Weld World

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“…Применение мягких сварных швов для сварки высокопрочных сталей до последнего времени считалось недопустимым [15,16]. Причиной служили низкие значения пределов текучести материалов сварного шва.…”

Section: Introductionunclassified

The Ultimate Load Estimation of Welded Joints of High-Strength Steels subject to Mechanical and Geometric Heterogeneity

Сапожников

Ivanov

Shcherbakov

2020

PNRPU Mechanics Bulletin

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In this paper we consider the problems arising in the numerical estimation of the ultimate load of welded joints of high-strength steels with slight hardening. The stress concentrator in the transition node from the deposited to the base metal is modeled based on the example of welding a roller wire on a plate made of high-strength steel. The use of welding wire with a yield point lower than that of the base metal allowed to simulate areas of the welded joint with heterogeneous mechanical properties. The geometry of three areas of the welded joint is studied, i.e. weld metal, heat-affected zone (HAZ) and the base metal. Mechanical properties of all three areas are determined by calculation and experimentally. For this purpose, it is proposed to consider the material in all sections as ideally elastic-plastic, and the yield strength is uniquely associated with the hardness in the indentation zone (a Rockwell diamond cone is used). Calculations of the inelastic indentation process by the finite element method (FEM) in axis-symmetric formulation allowed obtaining a linear relationship between the hardness and the yield strength with a coefficient of 0.418. Tests at a quasi-static three-point bend (with stretching in the surfacing area) were carried out on sample beams cut perpendicular to the direction of welding. The “force-deflection” diagrams are obtained and compared with the calculated curves (FEM in a three-dimensional formulation with an explicit consideration of the complex configuration of all sections and different yield stress in the areas determined by local hardness values). There is a good agreement between the calculated and experimental ultimate loads. The proposed method of the three-stage study (determination of local hardness, yield strength in the areas and the ultimate load) can be effectively used to assess the ultimate loads of the welded joints due to the low parametricity of the proposed models of materials inelastic deformation in areas for which it is impossible to manufacture standard samples for the study of mechanical properties. The experimental study of the strengthening effect of the seam with a stress concentrator in the form of an angle of 90 degrees on the value of the ultimate bending load showed that the removal of the deposited metal does not lead to an increase in the ultimate load of the welded joint when using the welding wire of low-carbon high-plastic steel.

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“…For UHSS and HSS the recommended value of t8/5 is often between 1 and 20 s [1,4]. However, with bainitic or martensitic steels that have high tensile strengths, the cooling rate in temperatures below 500 °C does have an effect on the microstructure and thus the mechanical properties [10,11]. For example, both lower bainite and martensite form in temperatures below 500 °C and both of these microstructures have good tensile strength properties.…”

Section: Introductionmentioning

confidence: 99%

Effect of enhanced weld cooling on the mechanical properties of a structural steel with a yield strength of 700 MPa

2020

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In this study, we present the effect of enhanced cooling on the mechanical properties of a high-strength low-alloy steel (having a yield strength of 700 MPa) following a single-pass weld process. The properties evaluated in this study include uniform elongation, impact toughness, yield, tensile and fatigue strengths alongside the cooling time of the weld. With the steel used in this study, the enhanced cooling resulted in a weld joint characterized with excellent cross-weld uniform elongation, yield and fatigue strength. The intensified cooling reduced the time it takes for the weld to reach 100 °C by around 190 s. Not only the fusion line of the weld was less pronounced, but also the grain size of the CGHAZ was greatly refined as a result of the enhanced cooling. The results indicate that combining external cooling to the welding processes can be beneficial for the studied high-strength steel.

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Effect of forced cooling after welding on CGHAZ mechanical properties of a martensitic steel

Cited by 5 publications

References 18 publications

Effect of enhanced cooling on mechanical properties of a multipass welded martensitic steel

Effect of enhanced cooling on mechanical properties of a multipass welded martensitic steel

The Ultimate Load Estimation of Welded Joints of High-Strength Steels subject to Mechanical and Geometric Heterogeneity

Effect of enhanced weld cooling on the mechanical properties of a structural steel with a yield strength of 700 MPa

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