Untitled

Ma, Hang

doi:10.1023/a:1007484026645

Cited by 16 publications

(6 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The maximum value of each stress component found at the elastic-plastic interface in the process zone is expressed by r xx(max) & 1.6r ys , r yy(max) & 2.6r ys , and r zz(max) & 2.1r ys [17,19] although these exact values have to be calculated through numerical simulations because the stresses depend on the geometry of the notch tip, ligament length, specimen thickness, and anisotropic properties. In addition, the stresses in the process zone have the distribution shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Effect of initial notch orientation on fracture toughness in fail-safe steel

Inoue

Kimura

2012

J Mater Sci

View full text Add to dashboard Cite

A 0.4C-2Si-1Cr-1Mo steel bar with an ultrafine-elongated grain (UFEG) structures was produced by multi-pass warm caliber rolling. The test sample was machined from the rolled bar with 0°, 45°, and 90°rotation along the rolling direction, and a static three-point bending test was conducted at ambient temperature. The toughness anisotropy on the steel with UFEG structures were studied, including the crack propagation on the basis of the microstructural features. The strength and toughness decreased with an increase in the rotation angle along the rolling direction. The toughness decreased drastically, compared to the strength. The notch orientation dependence on toughness is due to differences in the spatial distribution of weak sites such as {100} cleavage planes and boundaries of elongated grains. For the toughness design in ultrafine-grained materials, it is essential to understand the spatial distribution of these weak sites as well as the grain size.

show abstract

Section: Resultsmentioning

confidence: 99%

Effect of initial notch orientation on fracture toughness in fail-safe steel

Inoue

Kimura

2012

J Mater Sci

View full text Add to dashboard Cite

show abstract

“…This is attributed to a difference in the brittle fracture stresses in each direction associated with microstructural features. The brittle fracture stress, σ F , related to weak sites such as the cleavage planes or the grain boundaries is a function of the crack size (it is replaced by the effective grain size, d eff ), and it is generally independent of temperature [31,32]. Hence, the σ F increases with the decreasing grain size.…”

Section: Strength-toughness Balancementioning

confidence: 99%

Toughening of Low-Alloy Steel by Ultrafine-Grained Structure (Development of Fracture Control from Microstructure Design)

Inoue¹

2016

Fracture Mechanics - Properties, Patterns and Behaviours

View full text Add to dashboard Cite

Microstructural design for improving the strength-toughness balance was studied in low-alloy steel. Medium-carbon steel bars with microstructures of two types such as an ultrafine elongated grain (UFEG) structure and an ultrafine equiaxed grain (UFG) structure were fabricated by multi-pass warm caliber rolling and subsequent annealing. Conventionally, quenched and tempered steel with a martensitic structure and lowcarbon steel with a ferrite-pearlite structure were also prepared. The tensile and threepoint bending tests were conducted for all samples. In particular, the fracture behavior after the bending test was observed in detail and investigated, including the effect of microstructure features. As a result, the strength-toughness balance of the UFEG steel was excellent compared with that of all other steels. The present results provide useful guidelines for designing microstructure to improve the strength-toughness balance in metallic materials.

show abstract

“…E=1/2*V*σ ij *ε ij (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) where the σ ij , ε ij are the relaxed stress and strain in the final state calculated as in the previous section. For example, in the case of the K-S relationship in pure Fe, the strain energy barrier according to Eqn.…”

Section: Necessity Of Invariant Plane Strain Conditionmentioning

confidence: 99%

“…However, if both K-S and N-W relations co-exist in alternating laths of a sandwich structure, according to Eqn. 4-1 and 4-2, the macroscopic shape deformation associated with overall phase transformation can be described as: (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23) where x is the volume fraction of the K-S related martensite crystal. In order to produce an invariant plane strain, one of the principal distortions of the overall deformation matrix has to be unity.…”

Section: Achievement Of Invariant Strain Conditionmentioning

confidence: 99%

“…1-3 (b). [11,12,13] It is generally recognized that the yield strength will decrease as temperature increases whereas the fracture strength will remain almost unchanged with temperature. Thus, at temperatures above the ductile -brittle transition temperature (DBTT or T B ), as the applied stress increases towards failure, the stress at the tip of a pre-existing crack reaches yield strength before the brittle fracture strength is reached.…”

mentioning

confidence: 99%

See 1 more Smart Citation

The limit of strength and toughness of steel

Guo¹

2001

View full text Add to dashboard Cite

The ideal structural steel combines high strength with high fracture toughness. This dissertation discusses the governing principles of strength and toughness, along with the approaches that can be used to improve these properties and the inherent limits to how strong and tough a steel can be.Chapter I provides the background on fracture mechanics and describes the factors that affect cleavage fracture from atomic, microstructural and macroscopic levels. From such considerations, the inherent resistance to cleavage fracture is apparent.Chapter II discusses the ideal fracture strength and the critical fracture strength in high strength steels. Recent ab intio computations predict an ideal cleavage strength of Fe near 14 GPa on {100} planes, indicating that the normal fracture mode of high strength steel, 1 characterized by a yield strength greater than about 4 GPa is brittle. A preliminary study of the effect of alloying with Ni shows a trend of decreasing brittle behavior with increasing Ni content. More sophisticated methods to study this effect are proposed.Chapter III examines the practical methods for achieving properties that approach the limits of strength and toughness of steel. The discussion focuses on grain refinement through thermal treatments in lath martensitic steels. The objective is to limit the crystallographic coherence length for transgranular cleavage propagation. A new method is presented for directly disrupting the crystallographic orientation alignment within a martensitic packet, and thereby achieving submicron effective grain size. This has been accomplished in AerMet 100 and 9Ni steel by an alternate "intercritical annealing" (L) and "reversion" (Q) treatment. An "L" treatment creates a dual-phase microstructure containing fine parallel laths with different alloy contents. Subsequent austenite reversion ("Q" treatment) leads to a two-step martensitic transformation during cooling, disrupting the laths within a packet and generating a large misorientation between the adjacent laths.Chapter IV explains why this grain refinement can be accomplished, as described by martensitic transformation theory. It is shown that all KS and NW relationships can be divided into three Bain variant groups based on their transformation strain matrix. Only the variants from different Bain groups will have a large angle of misorientation. Furthermore, multiple variants from different Bain groups might appear if the geometric constraint prevents the relaxation of transformation strain. 2To my wife, Nan, and my parents i

show abstract

Untitled

Cited by 16 publications

References 25 publications

Effect of initial notch orientation on fracture toughness in fail-safe steel

Effect of initial notch orientation on fracture toughness in fail-safe steel

Toughening of Low-Alloy Steel by Ultrafine-Grained Structure (Development of Fracture Control from Microstructure Design)

The limit of strength and toughness of steel

Contact Info

Product

Resources

About