Effect of titanium in aluminium matrix on densification and forming limit of P/M composites during upsetting process

Abstract

The present work investigates the densification and forming limit of sintered porous aluminium-titanium preforms for various relative densities and titanium particles. The compacts of 1 aspect ratio with 2-6% of titanium contents in aluminium matrix for various relative densities were prepared through powder metallurgy route by applying suitable powder forming pressures. A sequence of the cold upsetting test has been carried out using 0.5 MN capacity of hydraulic press machine at 0.1 s −1 strain rate. The relation between true axial strain and preforms relative density was plotted, and the influence of titanium and relative density on the densification curve was investigated at various compaction pressures. The specimen properties like apparent strain hardening exponent (n a) and apparent strength coefficient (K a) was determined through stepwise incremental deformation tests. The critical transition density (CTD) vide forming limit diagram was determined from the plot of n a and K a concerning the preforms relative density, and it was found to be 85.9%, 87.7% and 88% for 2%, 4% and 6% of titanium in the aluminium matrix. The CTD values of porous aluminium-titanium preforms were compared with those of the previous work of porous aluminium-copper preforms under the same compositions. Also, the average grain size of the components was determined and it is observed that 2% of titanium contains a larger grain size compared to other compositions. Hence, a higher forming limit was obtained in 2% of titanium reinforced with aluminium matrix.

A novel method to improve the critical damage parameter of powder metallurgical components during the cold upsetting

“…The amount of porosity has increased with the rise in the compositions of Ti contents which could reduce the RD and the flow behaviour of the samples. 34 Therefore, the effective strain of the sample has reduced due to the larger amounts of pores. Hence, the VN in the sample has been increased and the CDP of the material has reduced.…”

“…The flow behaviour of the P/M samples is obstructed by the addition of reinforcements in the samples. 31,33,34 Therefore, the failure strain has reduced for more amounts of Ti contents in the workpiece. Also, the amount of porosity has increased with the rise in the compositions of Ti contents which could reduce the densification of the samples.…”

“…31,32 For sample with the higher densification, the preforms flow behaviour has increased and hence the failure strain of the component is improved due to the reduction in the porosity. [31][32][33][34] The amount of porosity for the porous Al -4% Ti samples for various IRDs was determined and the results are given in Supplemental Table 2. It is observed from Supplemental Table 2 that the levels of porosity have reduced with the higher SH conditions (250 C).…”

“…Hence, the flow behaviour of the sample has reduced due to the lower densification. [31][32][33][34] Therefore, the effective strain of the sample has reduced because of the higher amount of porosity. Thus, the VN in the sample has increased and the CDP of the sample has reduced.…”

Role of localized heating on the workability of powder metallurgical Al–4% Ti components in cold compression

“…14,15 Many researchers have evaluated the workability of various P/M samples and they found that the workability of the samples relies heavily on the pores present in the workpiece. [16][17][18][19][20][21][22][23][24][25] They observed that the workability is high for samples with fewer pores and the workability is low for samples with more pores. The authors performed the upsetting test on sintered P/M steel samples and investigated the influence of porosity on the microstructure evolution during the process.…”