A new method for automated reconstruction of pre-transformation microstructures

A new method, referred to as the cluster method, is proposed and tested for the reconstruction of pre-transformation microstructure in Ti-6Al-4V alloy. The cluster method begins by constructing clusters of daughter grains (room-temperature hcp -phase) that have a high probability of being transformed from the same parent grain (high-temperature bcc -phase). These clusters are then grown, and back-transformed to the parent grain orientations using the summation of mutual misorientation angle method' (SMMA method). The cluster method is validated by comparing the obtained results with the results of the SMMA and triplet methods

Microstructure Evolution and Abrasive Wear Behavior of Ti-6Al-4V Alloy

This paper investigates the effect of quenching and aging treatment on microstructure and abrasive wear of Ti-6Al-4V alloy. The as-received alloy was solution treated at 1339 K, then oil quenched, followed by aging at 823 K for 4 h (14,400 s). The microstructures of as-received and quench-aged specimens were characterized by using optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, and electron backscattered diffraction techniques. The as-received specimen consisted of very fine alpha grains (average grain size 2 mu m) with beta phase uniformly dispersed throughout. The microstructure of the quench-aged specimen showed alpha plates (formed by the decomposition of alpha' during aging). The beta phase precipitated out of alpha' martensite during aging and hence was dispersed uniformly in the alpha matrix. Ti-6Al-4V alloy was quench-aged to achieve maximum hardness with a view that the increased hardness would lead to an improvement in abrasive wear behavior. Two-body abrasive wear tests were carried out on the as-received and quench-aged specimens using pin-on-disk apparatus with SiC as abrasive media (150-grit size). The effect of sliding distance and normal load on the abrasive wear behavior was studied. The wear resistance of the as-received specimen was greater than that of quench-aged specimen, while hardness of the as-received specimen was lower than that of quench-aged specimen. The abrasive wear behavior of Ti-6Al-4V alloy has been explained based on morphology/microstructure of the alloy and the associated wear mechanism(s)