Synthesis and Characterization of 17 Cr …
287
The present investigation aims towards the development of 17 Cr–0.3Y 2 O 3 with
Zirconium oxide (0.5 wt%), titanium (0.1wt%), and aluminium (4wt%) will be milled
in a high energy ball milling to obtain the nano crystallite structure and the milled
powder will be consolidated by vacuum hot pressing.
2 Materials and Processes
2.1 Processing of Ferritic ODS Steel Powder
Mechanical Alloying (MA) route was performed using the high energy planetary ball
milling equipment (Fritsch Pulversitte PM400) under a closed environment, constant
flow with help of a stainless steel vial and balls of 10 mm diameter. The ball milling
process parameters were used of 300 rpm with the ball to powder ratio of 10:1, milled
at 20 h. During MA to avoid combustion, control reagent of toluene was used. The
presence of the toluene medium resists the formation of agglomeration of particles
during the repeated collision and reduces the size of the particle.
Mechanical ball milling was conducted at different milling times (0 h, 5 h, 10 h,
15 h, 20 h) intervals. Finally, the different stages of milled powders were taken for
phase transformation using X-Ray Diffraction (XRD), with the condition of Cu Kα
(λ = 1.542 Å). Mechanically milled powders using Debye’s–Scherrer method the
crystallite size and lattice strain were calculated. The rule of mixtures was used to
calculate the theoretical density of the compositions of the alloys as shown in Table 1.
The consolidated 20 h of milled powders were sintered using vacuum hot pressing
in uni-directionally at a temperature and pressure level of 1180 °C, 60 MPa with the
dwell time of 90 min and vacuum level of 10
−3 Torr. Hot pressing was done at
10 °C per min during heating and 50 °C/min during cooling for the sintering cycle.
With the help of appropriate graphite dies and punch assembly, hot-pressed billets
were developed of 30 mm diameter and 10 mm height, as shown in Fig. 1. Sintered
samples densities were measured using mass and physical dimensions method with
an electronic balance in the precision of 0.1 mg. To identify the uniform distribution
of oxide particles the TEM studies were carried out for the alloys. Sample preparation
for TEM studies through Gatan model 656 (Dimple grinding) and Gatan model 691
(Ion milling) Process. Hot-pressed alloys hardness was measured using Vicker’s
hardness tester with a functional load of 5 kg and dwell time of 10 s.
Table 1 430L pre-alloyed powders and its chemical composition of alloys
Powder Grade Cr wt% Mn wt% Si wt% C nwt% P wt% S wt% Fe wt% Theoretical
density (g/cc)
430L
17
0.89
0.89
0.02
0.01
0.01
Bal
7.70
Alloy A
(430L + 0.3Y 2 O 3 + 0.5ZrO 2 + 0.1Ti) wt%
7.67
Alloy B
(430L + 0.3Y 2 O 3 + 0.5ZrO 2 + 0.1Ti + 4Al) wt%
7.47
287
The present investigation aims towards the development of 17 Cr–0.3Y 2 O 3 with
Zirconium oxide (0.5 wt%), titanium (0.1wt%), and aluminium (4wt%) will be milled
in a high energy ball milling to obtain the nano crystallite structure and the milled
powder will be consolidated by vacuum hot pressing.
2 Materials and Processes
2.1 Processing of Ferritic ODS Steel Powder
Mechanical Alloying (MA) route was performed using the high energy planetary ball
milling equipment (Fritsch Pulversitte PM400) under a closed environment, constant
flow with help of a stainless steel vial and balls of 10 mm diameter. The ball milling
process parameters were used of 300 rpm with the ball to powder ratio of 10:1, milled
at 20 h. During MA to avoid combustion, control reagent of toluene was used. The
presence of the toluene medium resists the formation of agglomeration of particles
during the repeated collision and reduces the size of the particle.
Mechanical ball milling was conducted at different milling times (0 h, 5 h, 10 h,
15 h, 20 h) intervals. Finally, the different stages of milled powders were taken for
phase transformation using X-Ray Diffraction (XRD), with the condition of Cu Kα
(λ = 1.542 Å). Mechanically milled powders using Debye’s–Scherrer method the
crystallite size and lattice strain were calculated. The rule of mixtures was used to
calculate the theoretical density of the compositions of the alloys as shown in Table 1.
The consolidated 20 h of milled powders were sintered using vacuum hot pressing
in uni-directionally at a temperature and pressure level of 1180 °C, 60 MPa with the
dwell time of 90 min and vacuum level of 10
−3 Torr. Hot pressing was done at
10 °C per min during heating and 50 °C/min during cooling for the sintering cycle.
With the help of appropriate graphite dies and punch assembly, hot-pressed billets
were developed of 30 mm diameter and 10 mm height, as shown in Fig. 1. Sintered
samples densities were measured using mass and physical dimensions method with
an electronic balance in the precision of 0.1 mg. To identify the uniform distribution
of oxide particles the TEM studies were carried out for the alloys. Sample preparation
for TEM studies through Gatan model 656 (Dimple grinding) and Gatan model 691
(Ion milling) Process. Hot-pressed alloys hardness was measured using Vicker’s
hardness tester with a functional load of 5 kg and dwell time of 10 s.
Table 1 430L pre-alloyed powders and its chemical composition of alloys
Powder Grade Cr wt% Mn wt% Si wt% C nwt% P wt% S wt% Fe wt% Theoretical
density (g/cc)
430L
17
0.89
0.89
0.02
0.01
0.01
Bal
7.70
Alloy A
(430L + 0.3Y 2 O 3 + 0.5ZrO 2 + 0.1Ti) wt%
7.67
Alloy B
(430L + 0.3Y 2 O 3 + 0.5ZrO 2 + 0.1Ti + 4Al) wt%
7.47