Session 18: Materials Processing
Chairs:
Márcio Ziviani
Departamento de Engenharia Mecânica
UFMG
Comissão Organizadora e Editorial
do ENCIT 2000
Departamento de Endgenharia Mecânica
Universidade Federal do Rio Grande do Sul
SOME CAUSES OF DIFFERENCES BETWEEN ANALYTICAL RESULTS AND TEMPERATURE MEASUREMENTS IN WELD HAZ
Luciano Amaury dos Santos
- emc3las@emc.ufsc.br
Antônio Fábio
Carvalho da Silva - fabio@emc.ufsc.br
Carlos Enrique Niño
- cenico@emc.ufsc.br
Augusto José de Almeida
Buschinelli - buschi@emc.ufsc.br
Departamento de Engenharia
Mecânica, UFSC
CEP 88040-900, Florianópolis,
SC, Brasil
Abstract. In this paper are discussed some causes of the differences observed between temperature measurements, taken through thermocouples inserted in the weld heat affected zone (HAZ), and analytical results. In this discussion (partially based in numerical solutions) some effects disregarded in the analytical solution are considered: that of the latent heat of fusion and that of the temperature dependence of the thermal conductivity (the effect of the stirring present inside the weld pool can be approximately taken in account by the use of an artificially augmented conductivity value for the molten material). All these effect seem to be important in experiments like those considered in the present work, but not at the point of making the analytical solution (and its comparison with the measurements) uninteresting. Special attention is given to welding with thermal pulsing.
Keywords: Welding, Heat conduction,
Temperature measurement
NEW BOUNDS FOR THERMAL CONDUCTIVITY OF RECYCLED POLYMERIC MATRIX COMPOSITES
Antonio F. _ Avila { aavila@dedalus.lcc.ufmg.br
Universidade Federal de
Minas Gerais, Composites Laboratory
Department of Mechanical
Engineering, 31270{901 Belo Horizonte, Brazil
Polymeric matrix composites
(PMC) are used in engineering applications as they present low density
and high strength. However, they are not used in large{scale
applications due to their
high cost. The large variety of thermoplastic matrices allow us to experiment
di_erent types of resin combinations creating the so{called melt-blended
matrices. In this model, a binary combination of thermoplastics is used
to form a fully recycled melt-blended matrix. The HDPE/PET matrix is assumed
to be composed by PET spheroidal inclusions diluted in a HDPE substrate,
and the resulting matrix is used to form a unidirectional laminated polymeric
matrix composite. Due to chemical reac- tions involved during the matrices
combination process and between the resulting matrix and the E-glass _bers,
the weak interface _ber/matrix condition must be considered. To model the
thermal-elastic behavior of HDPE/PET-E glass _ber composites a double step
homogenization procedure is proposed. The concentric spheres model is applied
to obtain the melt-blended matrix e_ective properties, and to describe
the overall composite behav- ior the composite assemblage model under weak
interface condition is considered. The new expression proposed for the
e_ective transverse thermal conductivity is based on the analogy between
shear loading and conductivity. The numerical simulations are compared
against analytical models, Hashin and Rosen, and the representative volume
element approach with good agreement.
Keywords:Bound for Thermal
Conductivity, Laminated Polymeric Matrix Composites, Recycled composites
TEXTURE AND PROPERTIES OF WARM ROLLED INTERSTICIAL FREE STEELS
José R. G. Matheus
- d4andrea@epq.ime.eb.br
Andréa Machado Lopes
- d4andrea@epq.ime.eb.br
Hani Hussein ALY El-Sharawy
- haniha@epq.ime.eb.br
Carlos Sérgio da
Costa Viana - d4viana@epq.ime.eb.br
Instituto Militar de Engenharia,
Department of Mechanical and Materials Engineering
Praça General Tibúrcio
80, Praia Vermelha, CEP: 22290-270 - Rio de Janeiro, RJ, Brazil
The Interstitial Free ( I. F. ) steels are novel materials of Ultra High Drawability used extensively in modern car industry, especially for the fabrication of car bodies of intricate and modern design. The exceptional formability is attributed to the specific chemical composition of very low carbon ( ~ 0.003-0.006 % ), titanium microadditions ( ~ 0.06-0.09 % ), and to the development of desired crystallographic texture during the steel thermomechanical processing. Stable carbides are formed in the austenite range, rendering the steel matrix almost carbon free, which allows high thickness reductions in the ferrite range. An I. F. steel was rolled at 600oC and 400oC under 60 % reductions, and cooled in air. At these temperatures, recrystallization is inhibited and the texture developed during rolling may be analyzed at room temperature. Texture was determined from Electron Back Scattering Diffraction (EBSP) using Orientation Imaging Microscopy (OIM). The Crystal Orientation Distribution Functions (CODF) correspond to the average texture across the sample thickness, and along the rolling direction. The results were compared with the CODF for samples rolled at room temperature. Independent of the rolling temperature, sample annealing returns similar texture components. These results encourage the development of continuous IF steels rolling schedules spanning down to lower temperatures
Keywords: Interstitial Free
Steel, Warm Rolling, Crystallographic Texture, Sheet Drawability