Direct-Quenched Structural Steels

Kömi, Jukka; Karjalainen, Pentti; Porter, David

doi:10.1081/e-eisa-120049737

Cited by 24 publications

(23 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A possible explanation for this phenomenon is the higher S and Mn contents of DQ2 (Table 1). Mn tends to segregate along the centerline and form MnS inclusions, which affect negatively hydrogen-induced cracking 2,3,5,26,27 . Therefore, lower Mn content of DQ1 and RQ steels reduces the centerline segregation and the amount of MnS inclusions.…”

Section: Defining Of Test Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Hydrogen-Induced Cracking of 500 HBW Steels Studied Using a Novel Tuning-Fork Test with Integrated Loadcell System

et al. 2020

Self Cite

View full text Add to dashboard Cite

Hydrogen embrittlement is a well-known problem with high-strength steels. An important aspect of hydrogen embrittlement research is the effect of the prior austenite grain (PAG) structure on hydrogen-induced fracture. The microstructural anisotropy of PAG structure depends on the steel manufacturing process. In this study, 500 HBW martensitic steels with different PAG structures are investigated with a novel tuning-fork test that utilizes an integrated loadcell system. The loadcell clamping system is used during hydrogen charging allowing tracking of the applied force throughout the tests, which enables detection of separate phases of cracking and time-to-fracture. The elongated PAG morphology produces different results depending on the crack path direction in relation to the rolling direction, whereas the equiaxed PAG morphology does not manifest an orientation dependence. Depending on the PAG shape, also the fracture morphology differs. Time-to-fracture results show that elongated grain morphologies with transgranular quasi-cleavage crack propagation are more beneficial against hydrogen-induced fracture than equiaxed grain structure with intergranular crack propagation. Our results demonstrate that the shape of the PAG structure plays an important role in the crack propagation mechanism and that it is important to consider the possible direction of hydrogen-induced cracks in the final structural applications.

show abstract

Section: Defining Of Test Resultsmentioning

confidence: 99%

“…There is an increasing demand for high-strength steels due to economical necessities and environmental impacts 1 . Higher strength provides possibilities to use lighter steel structures, which correspond to energy efficiency, cost savings, and reduced carbon footprint 2 . However, the use of high-strength steels may be restricted, e.g.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen-Induced Cracking of 500 HBW Steels Studied Using a Novel Tuning-Fork Test with Integrated Loadcell System

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…The 960 grade chosen for this study has a dual-phase microstructure consisting of bainite and martensite. 12 The grade is classified based on its microstructure as either dual-phase or complex-phase steel because the bainite consists of several metallographic phases. The monotonic tensile properties of the material along with the hardness measurement value are given in Table 1.…”

Section: Methodsmentioning

confidence: 99%

Experimental fatigue characterization and elasto-plastic finite element analysis of notched specimens made of direct-quenched ultra-high-strength steel

Dabiri

Isakov²,

Skriko

et al. 2016

Proceedings of the Institution of Mechanical Engineers, Part C:

View full text Add to dashboard Cite

The low-cycle fatigue behavior of a direct-quenched ultra-high-strength steel was experimentally characterized and numerically modeled. Fatigue and cyclic parameters were obtained by conducting strain-controlled low-cycle fatigue tests on uniform-gage specimens. Surface residual stresses were minimized and axial deflection eliminated by optimization of machining parameters and post-machining electro-polishing. The steel material showed cyclic softening and decrease in yield strength. Cyclic softening, stabilized response, and the cyclic stress–strain curve were numerically simulated using finite element analysis with a model capable of describing nonlinear kinematic-isotropic hardening. The results showed good agreement with experimental values and validated the model’s ability to simulate the softening and cyclic stabilization of the material under investigation. The same numerical method was then used in elasto-plastic stress–strain analysis of notched specimens made of the same material to make fatigue life predictions. Estimated lives were compared with predictions made by analytical approximations such as the linear rule, Neuber’s rule, and the strain energy density method and verified by experimental data. Finite element analysis using stabilized cyclic response yields the most accurate predictions and, thus, provides an effective tool for the fatigue analysis of this material.

show abstract

“…These low-carbon ultra-high-strength steels, used in the as-quenched condition, are a modern economical type of structural steel with yield strengths above 900 MPa. They combine high strength with sufficient toughness, formability and weldability, and are typically used in weight-critical and high-performance structures [35]. It is shown for the first time that the transition temperatures do not correlate with yield strength alone but that, in conjunction with the area percentage of cleavage planes on the macroscopical crack plane, a simple stress-intensity term described with yield strength and effective coarse grain size is able to model the transition temperatures with good accuracy.…”

Section: Introductionmentioning

confidence: 99%

Effect of microstructure on the impact toughness transition temperature of direct-quenched steels

Pallaspuro

Kaijalainen

Mehtonen

et al. 2018

Materials Science and Engineering: A

Self Cite

View full text Add to dashboard Cite

A sufficient level of toughness at low temperatures is paramount for the use of structural steels intended for arctic applications. Therefore, it is important for the steel industry to identify the factors that control brittle fracture toughness. In this study, the quantitative effect of microstructure on the impact toughness transition temperature has been investigated with 18 different thermomechanically rolled and direct-quenched low-carbon ultra-high-strength steels with varying martensite and bainite contents. The steels were produced by altering their chemical composition, the finish rolling temperature and the total reduction of the prior austenite grains in the non-recrystallisation temperature regime, i.e. austenite pancaking, and characterised in terms of microstructural constituents, grain size distributions and texture as well as by using Charpy-V impact and tensile testing. It is shown for the first time that the impact toughness transition temperatures T 28J and T 50 closely follow a dynamic reference toughness, defined by yield strength and the size of the coarsest grains in the effective grain size distribution at 80th percentile. Decreasing the area fraction of {100} cleavage planes oriented within 15°of the macroscopic fracture plane by increasing austenite pancaking is also shown to improve T 28J. The best toughness is achieved with the lowest finish rolling temperatures that are nevertheless high enough to avoid the subsequent formation of granular bainite, which weakens both the toughness and strength. The results show that it is perfectly possible to produce untempered ultra-high-strength martensitic and martensitic-bainitic structural steels with adequate low-temperature toughness when the grain size is properly controlled.

show abstract

Direct-Quenched Structural Steels

Cited by 24 publications

References 36 publications

Hydrogen-Induced Cracking of 500 HBW Steels Studied Using a Novel Tuning-Fork Test with Integrated Loadcell System

Hydrogen-Induced Cracking of 500 HBW Steels Studied Using a Novel Tuning-Fork Test with Integrated Loadcell System

Experimental fatigue characterization and elasto-plastic finite element analysis of notched specimens made of direct-quenched ultra-high-strength steel

Effect of microstructure on the impact toughness transition temperature of direct-quenched steels

Contact Info

Product

Resources

About