جوشکاری اصطکاکی اغتشاشی صفحات AA 2219 نورد شده

Interface behaviours and mechanical properties of filling friction stir weld joining AA 2219 

رفتارهای فصل مشترک وخواص مکانیکی جوشکاری اصطکاکی اغتشاشی

پرکردن اتصال AA2219

ABSTRACT

Being brittle and having low thermal conductivity, refractories suffer damage and sometimes fail in service as a result of thermal shock. While the approach of those making fine-grained technical ceramics is to make their products sufficiently strong to withstand thermal stresses the refractory technologist is more cunning. He uses, often little known, devices to provide resistance to thermal shock that minimise but do not eliminate damage to the component. In this paper the basic equations of thermal conduction and elasticity are presented and followed by some immediate results that should guide the designer of components subject to severe thermal environments. The influence of size and shape of the refractory components is then discussed along with ways in which refractory producers can engineer the thermal and mechanical properties. In particular, the methods used to tailor fracture behavior to optimize the thermal shock resistance are treated in some detail.

  

تاثیر انجماد بر تحول ریزساختاری فلز جوش پایه نیکل

Influence of solidification on the microstructural evolution

of nickel base weld metal

تاثیر انجماد بر تحول ریزساختاری فلز جوش پایه نیکل 

ABSTRACT

The effect of segregation resulting from solidification on the microstructural evolution of nickel base alloys was investigated. Two different groups of alloys were produced to simulate either the Hastelloy C type or the Inconel 625/718 type of alloys. Gravitational thermal analysis welding was performed on these experimental alloys and the extent of microsegregation in the weld metal was determined. Using composition profiles obtained from solidified microstructures, predictions of the phase stability of these microstructures were made based on metal d-level (Md) calculations. The maximum Md values obtained in these microstructures were compared with those critical to the formation of topologically close-packed (TCP) phases such as sigma, P, and Laves. These profiles showed an increase in the Md level in the interdendritic regions which was correlated to the formation of TCP phases.