This paper presents an investigation of the mechanism of the brittle–ductile cutting mode transition from the perspective of the mechanics. A mechanistic model is proposed to analyze the relationship between undeformed chip thickness, deformation, and stress levels in the elastic stage of the periodic chip formation process, regarding whether brittle or ductile mode deformation is to follow the...

[1] Geothermobarometric together with microand macro-structural data indicate ductile flow in the metamorphic core of the Himalaya in the Garhwal region of India. Peak metamorphic pressure and temperature increase dramatically across the Main Central Thrust (MCT) from !5 kbar and !550°C in the Lesser Himalayan Crystalline Sequence (LHCS) to !14 kbar and !850°C at !3 km above the MCT in the Grea...

The effects of silicon (Si) on the mechanical properties and fracture toughness of heavy-section ductile cast iron were investigated to develop material for spent-nuclear-fuel containers. Two castings with different Si contents of 1.78 wt.% and 2.74 wt.% were prepared. Four positions in the castings from the edge to the center, with different solidification cooling rates, were chosen for micros...

A framework for describing the deformation and failure responses of multi-phase polycrystalline microstructures is developed from micromechanical considerations and volume averaging techniques. Contributions from damage (i.e., displacement discontinuities such as cracks, voids, and shear bands) are captured explicitly in the framework’s kinematics and balance relations through additive decompos...

One of the basic mechanisms of radiation embrittlement of steels and welds is due to matrix damage. Embrittlement results in a raise in the ductile-to-brittle transition temperature, which is normally used as indicator of the degradation status of the material. Other methods different than mechanical tests can be used to follow embrittlement like small punch test, non-destructive measurements o...

The secondary-phase particles in metals, particularly those composed of non-metallic materials, are often detrimental to the mechanical properties of metals; thus, it is crucial to control inclusion formation and growth. One of the challenges is determining the three-dimensional morphology and inner structures of such inclusions. In this study, a non-aqueous solution electrolytic method and a r...

190 Abstract In this paper, a new analytical method for solving stable crack propagation problems in a ductile panel with a row of cracks, is presented. The main purpose of the present study is to estimate the maximum load carrying capacity of such panels accurately. The so called Elastic Plastic Finite Element Alternating Method (Pyo et al. (1994)) was extended to account for the propagating c...

We demonstrate the capability of optical coherence tomography (OCT) to perform topography of metallic surfaces after being subjected to ductile or brittle fracturing. Two steel samples, OL 37 and OL 52, and an antifriction Sn-Sb-Cu alloy were analyzed. Using an in-house-built swept source OCT system, height profiles were generated for the surfaces of the two samples. Based on such profiles, it ...

This paper models a stochastic measure of fatigue crack damage in ductile alloys that are commonly encountered in structures and machinery components of complex mechanical systems such as land, air, ocean, and space vehicles. The constitutive equations of the damage measure are built upon the physics of fracture mechanics and are substantiated by Karhunen-Loève decomposition of fatigue test dat...

Ductile fracture modeling still has to be improved at the macro and microscales. New numerical methods are applied to the limit analysis of cells containing one or several voids or void clusters. The results are compared with existing macroscopic models. Voids can also be introduced in analytical polycrystalline models, in order to combine plastic anisotropy and texture evolution with ductile f...