Microstructure and cleavage resistance of low-carbon bainitic steels

Brozzo, P.; Buzzichelli, G.; Mascanzoni, A.; Mirabile, M.

doi:10.1179/msc.1977.11.4.123

Cited by 132 publications

(50 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…First, the probability for a microcrack of size c to nucleate and to propagate across the M-A/matrix interface is given by [13] Then, the probability for the crack of size c to propagate across the bainite high-angle packet boundary is [14] Here, is the number of potential crack nuclei per unit volume, and D is the grain (packet) size. Following the weakest-link assumption, the failure probability of the whole specimen by cleavage fracture is then given by [15] In Eq. [15], is the number of potential cracking grains (bainite packets) per unit volume.…”

Section: Results Given By the Db Modelmentioning

confidence: 99%

Mechanisms and modeling of cleavage fracture in simulated heat-affected zone microstructures of a high-strength low alloy steel

Lambert-Perlade¹,

Gourgues

Besson

et al. 2004

Metall Mater Trans A

241

View full text Add to dashboard Cite

The effect of the welding cycle on the fracture toughness properties of high-strength low alloy (HSLA) steels is examined by means of thermal simulation of heat-affected zone (HAZ) microstructures. Tensile tests on notched bars and fracture toughness tests at various temperatures are performed together with fracture surface observations and cross-sectional analyses. The influence of martensite-austenite (M-A) constituents and of "crystallographic" bainite packets on cleavage fracture micromechanisms is, thus, evidenced as a function of temperature. Three weakest-link probabilistic models (the "Master-curve" (MC) approach, the Beremin model, and a "double-barrier" (DB) model) are applied to account for the ductileto-brittle transition (DBT) fracture toughness curve. Some analogy, but also differences, are found between the MC approach and the Beremin model. The DB model, having nonfitted, physically based scatter parameters, is applied to the martensite-containing HAZ microstructures and gives promising results.

show abstract

Section: Results Given By the Db Modelmentioning

confidence: 99%

Mechanisms and modeling of cleavage fracture in simulated heat-affected zone microstructures of a high-strength low alloy steel

Lambert-Perlade¹,

Gourgues

Besson

et al. 2004

Metall Mater Trans A

241

View full text Add to dashboard Cite

show abstract

“…Therefore, strengthening can be attributed to the observed refinement and randomization of the lath, block and packet size [17][18][19], corresponding to the change from pure martensite to lower bainite and auto-tempered martensite mixtures [20]. However, it is difficult to separate the effects of these features from each other, as they are very interrelated.…”

Section: Discussionmentioning

confidence: 99%

The Effects of Finish Rolling Temperature and Niobium Microalloying on the Microstructure and Properties of a Direct Quenched High-Strength Steel

Kaijalainen

Vähäkuopus

Somani

et al. 2017

Archives of Metallurgy and Materials

View full text Add to dashboard Cite

This paper comprehends the effects of finish rolling temperature (FRT) and Nb-microalloying on the microstructural evolution and resultant properties of a low carbon direct quenched steel in the yield strength category of ≥900 MPa. Results indicate that a decrease in FRT close to A r3 temperature significantly influenced the microstructure following phase transformation, especially at the subsurface (~50-400 μm) of the rolled strip. On decreasing the FRT, the subsurface microstructure revealed a fine mixture of ferrite and bainite obviously as a result of strain-induced transformation, whereas the structure at the centreline remained essentially martensitic. Further, Nb-microalloying promoted the formation of ferrite and bainite even at higher FRTs, thus influencing the mechanical properties. The microstructures of the hot-rolled strips were further corroborated with the aid of CCT diagrams.

show abstract

“…Taking K σ p = 2.24 (Brozzo et al 1977) and R eL at temperature t gy = −140 • C equal to 813 MPa, Fig. 8, the cleavage fracture stress is σ CF = 1,821 MPa.…”

Section: Fracture (Transition) Behaviour Of R7t Steelmentioning

confidence: 99%

“…Such observations have been made with relation to low carbon steels but are generally assumed to be relevant to most steels with a ferritic matrix. Therefore temperature-independent cleavage fracture stress and a propagation-controlled fracture process has been proposed and proved for bainitic steels (Brozzo et al 1977;Curry 1984;Holzmann et al 1995), martensitic steels (Norström and Vingsbo 1979;Bowen and Knott 1984) and fully pearlitic steels (Lewandowski and Thompson 1984, 1986Kavishe and Baker 1986;Alexander and Bernstein 1989).…”

Section: Introductionmentioning

confidence: 99%

Fracture behaviour and cleavage initiation in hypoeutectoid pearlitic steel

2007

View full text Add to dashboard Cite

The paper reports on an investigation of the micromechanism of cleavage fracture in hypoeutectoid pearlitic R7T steel, commonly used for producing railway wheels. The steel possesses extensive Lüders deformation, which somewhat complicates finite element (FE) modelling and analyses of fracture behaviour. Standard Charpy V-notch specimens were used in order to analyse the fracture behaviour at quasistatic and impact loading. Finite element 3D calculations were performed and the elastic-plastic behaviour of notched bars up to the fracture was simulated. Detailed fractographic analysis was carried out on a number of Charpy V-notch specimens in order to investigate the origin site of cleavage fracture initiation and its distance from the notch root. The suitability of the threecriterion micromechanical model (Chen et al. Acta Materialia 51:1841-1855, 2003 for cleavage initiation was verified. The R7T steel under investigation exhibited a cleavage fracture stress of 1,837 MPa. Its independence on temperature evidenced the micromechanism of cleavage fracture to be microcrack propagation-controlled. For the investigated blunt-notched bend bars, an active volume exists ahead of the notch root in which pearlite colony-associated initiation sites M. Holzmann · I. Dlouhý (B) are located. The cleavage fracture initiation of the steel is thus governed by the sites lying in the active volume. The active volume is determined by the values of three parameters. A plastic strain lying in interval from ε pmin to ε pmax (for the steel investigated from 0.033 to 0.108) is necessary to create a cleavage crack nucleus at any location within the active volume depending on the local pearlite properties. A stress triaxiality parameter ranging from h min to h max (from 0.93 to 1.39) is supposed to prevent the blunting process at the site of the cleavage nucleus. Once the main principal stress σ 1 exceeds the local cleavage fracture stress σ CFmin , an unstable global cleavage fracture occurs in a bluntnotched bar.

show abstract

Microstructure and cleavage resistance of low-carbon bainitic steels

Cited by 132 publications

References 14 publications

Mechanisms and modeling of cleavage fracture in simulated heat-affected zone microstructures of a high-strength low alloy steel

Mechanisms and modeling of cleavage fracture in simulated heat-affected zone microstructures of a high-strength low alloy steel

The Effects of Finish Rolling Temperature and Niobium Microalloying on the Microstructure and Properties of a Direct Quenched High-Strength Steel

Fracture behaviour and cleavage initiation in hypoeutectoid pearlitic steel

Contact Info

Product

Resources

About