Forming Technology of Large-diameter, Thin-walled and ... · Study on hot spinning technology of...
Transcript of Forming Technology of Large-diameter, Thin-walled and ... · Study on hot spinning technology of...
Forming Technology of Large-diameter, Thin-walled and Weldless Tube of TC4 Alloy
Qi Jun Li Qi Wang Cao Gen Yao Qun Shan Si Yuan Huang
Aerospace Research Institute of Material and Processing Technology ,Beijing 100076
In this paper, effect of parameters of spin forming on large-diameter, thin-wall and weld less tube of TC4 alloy was analyzed by finite element anal
ysis. In addition, the spinning technology for manufacturing the TC4 tube was optimized and the microstructure and the properties of original
material were investigated. Results show that the TC4 alloy tube with high precision is successfully manufactured by spin forming technology.
After spinforming and heat treatment, the microstructure and property can be improved.
Keywords: TOI alloy, large-diameter ,thin-walled ,weld less, spinforming
I. Introduction
In order to achieve the goal of light weight, large dimension and high strength materials, the large-diameter and thin-wall and weldless TC4 alloy tube was widely applied in the space flight system. At present, there are few references about the manufacturing technology of the large-diameter, thin-wall and weldless TC4 alloy tube. Due to the large resistance to deformation, it is difficult to manufacture the TC4 alloy tube by usual technology. The spinforming is an advanced technology for manufacturing the TC4 alloy tube. However, there are many factors affect the spinforming of TC4 alloy especially for the tube. In the background of the TC4 alloy tube (the size <1>6 70;i0
· 5 X 400
X 2;i0·
2 mm) served as a component in aerospace, the spinforming technology of a TC4 alloy was investigated.
2. Experimental
2. I Materials The TC4 alloy plate, with a thickness of 10 -
12mm and diameter of </>1150-1200 mm, was punched into a tube.
2. 2 Test Technology
On the basis of finite element model <FEM) simulation spinforming process, the technological parameter of spinforming and the technology of temperature control was investigated to make sure the forming and precision of the work piece. Because the spinforming causes the TC4 alloy to fracture in room temperature, the hot spinforming must be carried out, which can enhance the deformation capability and reduces the resistance to deformation and the components snapping back. At present, the hot spinforming is the main spinning technology for manufacture titanium components. Figure 1
shows the hot forming chart of TC4 alloy in some strain by thermal simulation experiment. Hot forming region is preferable from 800 to 900"C. During this region, dynamic recrystallization is easy to occur for TC4
alloy and also the flow stress is low.
"' -3 c - -4
-5 -6
-7+-'-"'=.-~~T'-'-'--"=..."-'--."'-',,__,_-'.-'--'--;
700 750 800 850 900 950 T,"C
preferable hot fonning region
Figure I. The hot forming chart of TC4 alloy
Heat treatment was conducted in order to stabilize the microstructure and reduce the relaxation of residual stress after spinning deformation. The microstructure of the alloy after heat treatment was analysis.
3. Results and Discussion
3. I Analysis of Technological Parameter Figure 2 shows the axial displacement of different
ratio of feeding. According to Figure 2, the influence of the ratio of feeding on the metal flow can be observed. When the ratio of feeding is quite small, the contact material region between roller and raw materi.al is very small and the distribution of deformation is inhomogeneous in thickness direction. It is easy to produce the band and follow slight bulge. While the ratio of feeding is large, the axial displacement in front of roller is also large, causing pile up and bulge, the metal axial flow is blocked; The metal axial flow is steady when the ratio
of feeding is 0. 6 mm/ r. Figure 3 shows the axial displacement of the ratio
of thinning. The corresponding curve with the axial displacement is indicated as Figure 4.
It is clear from Figure 3-Figure 4 that the axial displacement increases with the increase of the ratio of thinning. This indicates that the increase of the ratio of thinning can increase the axial flow. Also, the distribution of the axial displacement in thickness direction
changes with the ratio of thinning changed While during 20 %- 40 % , the distribution is even, while more than
• 2008 • Proceedings of the 12'h World Conference on Titanium
2.993e-001
2.609e-001
2.225e-001
1.840e-001
J.456e-001
J.072e-00 1
6.872e-002
3.029e-002
-8. l 47e-003
-4.658e-002
-8.501 e-002
( a ) 0.2mm/ r ratio
6.712e-001
5.986e-001
5.260e-001
4.533e-001
3.807e-001
3.081e-001
2.354e-001
l .628e-00 1
9.016e-002
J.752e-002
-5.5 11 e-002
( b ) 0.6mm/r ratio
l.051 e+OOO
8.654e-00 1
6.794e-001
4.934e-001
3.074e-001
l.214e-001
-6.455e-002
-2 .505e-00 1
-4.365e-001
-6.225e-00 1 ( c) 1.4mm/ r ratio
Figure 2. The axial displacement of different ratio of feeding
60 % , the axial displacement concentrates in the outer layer and deformation of metal in inner layer is difficult because of bulge.
4.337e-001
3.854e-001
3.371e-001
2.888e-001
2.405e-001
J.922e-00 1
1.439e-00 1
9.56 1e-002
4.73 le-002
-9.930e-004
-4.930e-002
( a) 20% ratio
6.712e-001
5.986e-001
5.260e-001
4.533e-001
3.807e-001
3.0Sle-001
2.354e-001
1.628e-001
9.016e-002
J.752e-002
-5 .51 1 e-002
( b ) 40% ratio
8.480e-001
7.337e-001
6.195e-001
5.053e-00 1
3.91 le-001
2.768e-00 1
l.626e-OOI
4.837e-002
-6.586e-002
-1 .801e-001
-2 .943e-001
( c ) 60% ratio
Figure 3. The axial displacement of different ratio of thinning
Figure 4 also demonstrates the situation of bulge with different ratio of the thinning. When rollers axially
9. Aerospace Applications • 2009 •
----60% 1.0 ---- 40%
20% E E 0.8
-::::-i:i E 0.6 " u
"' 0. "' :; 0.4
-;;; ·x "' 0.2
0.0 0.5 1.0 1.5 2.0 2.5 3 .0 thickness direction/ mm
Figure 4. Corresponding curve with the axial displacement
compress blank, the metal piles up in the deformational region, which lead to the deformation of bulge. While
the ratio of thinning is from 20 % to 40 % , the spinforming process can be normally carried out because that the bulge remains slight and stable. While more than 60 % , peeling happens because of seriously bulge (Figure 5) .
Figure S. Peeling
The results of FEM simulation show that it is suitable for spinforming and process control when the
ratio of feeding is 0. 6mm/ r and the ratio of thinning is in the region of 20 %~40%.
3. 2 Analysis of Spinning Technology
The experiment is carried out by multi-passes
spinforming. During the following pass of hot spin
forming, the work piece will contract and enclasp the
mandrel. In adition, the metal axial flow is blocked in
unformed section and forming section and bulge occurs (Figure 6) in front of roller, which lead to the reverse
Figure 6. Bulge
flow of metal and plump up ( Figure 7) in the back of roller. Therefore, the auxiliary spinning technology was
used to expand the diameter of work piece between passes of spinfoming, causing the work piece to sepa
rate from the mandrel. The metal axial fluidity is correspondingly enhanced. At last , the typical quality problem such as indirect extrusion and bulge , which appears easily during multi-passes spinforming of the large diameter and thin wall T C4 alloy tube, was solved.
Figure 7. Plump up
3. 3 Result Analysis on Temperature Control The temperature control is one of the key aspects
which affect the spinforming of the large diameter and thin wa ll T C4 alloy tube. Because the size of the raw
materials of spinning tube is large , it is difficult to maintain high temperature for the entire work piece and ensure the uniform of temperature. For stabilize the temperature of deformation region , the technology of district temperature control is used during the deformed region, the deformation region ( including region of contact in front of roller) and undeformed region.
Meanwhile, the temperature of mandrel was controlled before spinforming in order that the temperature of mandrel distributed unifomly and the inflationis consistent The heat transfer ra te of material is also reduced, which is advantage for temperature control of
the materials. Figure 8 shows the large diameter and thin wall
T C4 alloy tube with good quality by spinforming tech
nology( ct>670;i0· 5 X 400 X 2;i0
· 2 mm).
Figure 8. Weldless tube of TC4 alloy
The tube is cut off and precisely machined in the in
ner surf ace and the outer surface. Finally, the large-diame
ter and thin-wall and weldless TC4 alloy tube with high
• 2010 • Proceedings of the 12'h World Conference on Titanium
precision is successfully manufactured (Figure 8) .
3. 4 Analysis of Microstructure and Properties
Table 1 shows the properties of samples in differ-
ent conditions. It is clear that the strength changes slightly and plasticity increase markedly. This results show that the hot spinforming improved the properties
of TC4 alloy.
Table 1. The results of testing properties
Test sta tus Ultimate tensi le strength
ab b/ MPa
Raw material 940
heat treatment 780"C / l h 952
Figures 9~ 10 show microstructure of raw material and the materials after spinning, respectively. The microstructure of the TC4 alloy changes after spinforming. Firstly, the a+~ sheet structure of raw material disappears, the a lamellar structure and ~ structure among a lamellar structure are fell to pieces. Secondly, the grain size becomes smaller and many a+ ~ equiaxed structure come into being. While grains refining, many grains are stretched along the axial direction(Figure 10 (b)) especially for crphase. These stretched structure
distribute regularly along the axial direction and the corresponding result is the formation of fibrous-streamlined structure. These microstructure characteristics are advantageous for improve the properties of the raw
material.
Figure 9. The microstructure of the raw material
4. Conclusions
(1) The multi-passes hot spinforming technology
is a suitable technology for manufacturing TC4 alloy tube, the large-diameter, thin-wall and weldless TC4
alloy tube with high precision. ( 2 ) The auxiliary spinning technology and the
technology of district temperature control can effec
tively solve the model quality problem such as indirect extrusion and bulge and the difficulty of temperature
control. The large-diameter and thin-wall and weldless
TC4 alloy tube and precision control was successfu lly
manufactured by means of spinforming.
(3) After spinforming and treat treatment, the grain
size of TC4 alloy become small, the a+~ equiaxed micro-
the properties in room temperature
Yield strength ao. ,/MPa Ductility a/%
897 13
898 17. 3
structure is formed and the properties are enhanced. This condition is suitable for engineering application.
(a ) Tangential metallurgical microstructure
( b) Axial metall urgical microstructure
Figure 10. Microstructure of the materials after spinforming
(Annealing 780°C/lh)
REFERENCES 1) Chen Kuo Xian,Jia Wen Duo, the power spinning technology and
equipment.
2) Xu Hong Lie, the power spinning technology.
3) Xu Wen Chen,Shan De Bin,Chen Yu, Kang Da Chang,Lv Yan,
Study on hot spinning technology of tubular workpieces for
TA15 titanium alloy, FORGI G & STAMP! G TECH OLO
GY,2008,33(3) :56-59.
4) Xu Wen Chen,Zhang Heng Da,Shan De Bin, Guo Bin, Kang Da
Chang. hot spinning technology of wheel rim of TC4 titanium al
loy. MATERIALS SCIE CE & TECH OLOGY, 2008, 16 ( 1):
14-18.
5) Wong CC, Dean TA, Lin J. A review of spinning,shear forming
and flow forming processes [ J ]. Inter. J. Mach. Tool Manu. ,
2003 '43 :141921435.
9. Aerospace Applications • 2011 •
6) SHAN Debin, LU Yan, L I Ping, et al. Experiment study on process of cold2power spinning of Ti - 15 - 3 alloy[ J ]. J of Mater Process T echnol, 200 I , 115 ( 3) : 380 - 383.
7) Cao Yun Hong, application of titanium alloy forming technology
in winged missile, WINGED MISSILR, 2002; 7: 50-60.
8) Wang Zhen Sheng, Zhang Shun Fu. study on spinning technology of large-diameter titanium cylinder. FORGING TECHNOLOGY, 1999, I: 24-26.