Effect of boron contents on weldability in high strength steel

Lee, H. W.; Kim, Y. H.; Lee, S. H.; Lee, K. H.; Park, J. U.; Sung, J.H.

doi:10.1007/bf02916355

Cited by 29 publications

(9 citation statements)

References 4 publications

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“…A new generation of borontreated automotive steels are currently of interest because they can be hot stamped and subsequently quenched to produce a martensitic structure with high strength, typically in the range of 900 to 1200 MPa [17]. Studies on the effect of boron content on the weldability of high-strength steels indicate that increasing boron concentration above 100 ppm in the weld metal results in cracking [18]. Therefore, understanding the effect of boron on inter-dendritic and grain boundary segregation of carbon and phosphorous during welding is necessary for the development of phosphorous and boron-containing AHSS.…”

Section: Introductionmentioning

confidence: 99%

Elemental segregation during resistance spot welding of boron containing advanced high strength steels

Amirthalingam

Kwakernaak

et al. 2015

Weld World

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The partitioning behaviour of carbon, phosphorous and boron during the solidification of a resistance spot weld pool was studied using experimental simulations and a phase field model. Steels with varying carbon, phosphorous and boron contents were designed and subjected to a range of resistant spot welding thermal cycles. Mechanical properties were evaluated by hardness and cross tension tests and correlated with the weld microstructure. Phase field modelling results and experimental predictions show that the phosphorus concentration in the last area in the weld pool to solidify can reach about 0.38 wt% for a steel with a bulk concentration of 0.08 wt%. Elemental analysis indicates that in the absence of boron, the grain boundaries of columnar grains in the weld pool are decorated with phosphorous. As a result, a complete interface failure occurs during cross tension testing. With the addition of boron, apart from an increase in weld strength and plug diameter, the failure mode switches to a complete plug mode, resulting from the phosphorous depletion at the grain/inter-phase boundaries.

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Section: Introductionmentioning

confidence: 99%

Elemental segregation during resistance spot welding of boron containing advanced high strength steels

Amirthalingam

Kwakernaak

et al. 2015

Weld World

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“…At the same time, boron increases the hardenability of the steel impeding the diffusive transformations of austenite and, consequently, favouring the saturation of the Feα matrix with alloying components. Many research publications emphasize that, to prevent the worsening of the plastic properties of welds and their resistance to notch effect, the content of boron in the welds should be determined very precisely [23,24].…”

Section: Discussionmentioning

confidence: 99%

Primary Reasons for the Brittleness of Welded Joints in Steel T/P24

Gruszczyk¹,

Pawlyta²

2020

eBIS

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The article presents results of tests concerning the susceptibility of welds made of steel T/P24 (7CrMoVTiB10-10) to secondary hardness as well as the structure and the mechanical properties of the welds (KV, Rm, A5, Z and HV1) in the as-made state and after heat treatment performed at temperature restricted within the range of 100°C to 750°C. The tests revealed that the welding process triggered the decomposition of phases hardening steel 7CrMoVTiB10-10 and the transition of alloying components and impurities to the solution of body-centred cubic lattice A2 (bcc). A thesis formulated by the Authors in relation to the test results stated that the primary reason for the deterioration of the plastic properties of the welds was the phenomenon of solid solution hardening. The Authors emphasized the necessity of performing the detailed analysis of interactions of substitution atoms and other defects of the Feα lattice with interstitial atoms. In addition, the Authors indicated the necessity of changing the criteria applied when assessing the weldability of technologically advanced steels as well as pointed mistakes made during the industrial implementation of steel 7CrMoVTiB10-10.

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“…boron can reduce the austenite grain boundary energy via segregation which in further consequence leads to an increase of the energy barrier for ferrite nucleation on the grain boundary surface thus promoting intragranular nucleation events [7,14,[19][20][21]. Nevertheless, Lee et al [22] described that high boron contents exceeding 32 ppm lead to a reduction of AF and an increase of upper bainite in high strength low-alloy weld metal.…”

Section: Alloying Elementsmentioning

confidence: 99%

Microstructural evolution of 2.25Cr-1Mo-0.25V submerged-arc weld metal

et al. 2019

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Heat-resistant V-modified 2.25Cr-1Mo-0.25V-weld metal is commonly used in petrochemical industry for heavy wall pressure vessels in high-temperature hydrogen service. In order to improve the reactor efficiency, the weldments have to endure even higher temperatures and pressures. Acicular ferrite (AF) is often regarded as the optimum microstructure due to its good combination of strength and toughness. As few literature about the evolution of microstructure and the final microstructure constituents of 2.25Cr-1Mo-0.25V weld metal is available, the current paper intends to provide comprehensive information by means of microscopy, crystallographic examination via electron backscatter diffraction and in situ observation of the austenite to ferrite phase transformation via high-temperature laser scanning confocal microscopy (HT-LSCM). The investigated weld metal exhibits a high density of complex aluminium-silicon-manganese oxides with a spherical shape and large prior austenite grains, which in combination is beneficial for intragranular nucleation of AF. Nonetheless, the examination of the transformed final microstructure was not sufficient to make an unambiguous statement about the presence of AF within the 2.25Cr-1Mo-0.25V weld metal. Via in-situ HT-LSCM of the phase transformation, intragranular nucleation of AF at non-metallic inclusions within the austenite grains was detected, which confirms that even though the microstructure of 2.25Cr-1Mo-0.25V weld metal is mainly bainitic, small amounts of AF are present.

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Effect of boron contents on weldability in high strength steel

Cited by 29 publications

References 4 publications

Elemental segregation during resistance spot welding of boron containing advanced high strength steels

Elemental segregation during resistance spot welding of boron containing advanced high strength steels

Primary Reasons for the Brittleness of Welded Joints in Steel T/P24

Microstructural evolution of 2.25Cr-1Mo-0.25V submerged-arc weld metal

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