• Journal of Welding and Joining
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• v.8 no.4
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• pp.20-26
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• 1990

In this study, to make research on its optimum condition in friction weld when the heating pressure is change during 1.6 to 3.0 $kgf/mm^2$, the experiment was performed with metal bearing under various condition; 1600 r.p.m spindile speed, 0.6 $kgf/mm^2$ preheating pressure, upset pressure 2.6 $kgf/mm^2$, 0.5 seconds preheating time, 1.7 seconds heating time, water and air was ejected 6 $kgf/mm^2$ into the bushing. On the basis of the experimental results, the following conclusion are drawn; 1) At the area of weld interface, the heardness is shown the maximum value and heat-affected zone about 0.5mm both sides. 2) Bending strength is shown the optimum heating pressure 2.4 kgf/mm. 3) With the approach of the flash, Sn is increased only 2 mm in A-alloy structure.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.6
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• pp.932-937
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• 2012

In the presented study, SM45C carbon steel parts were joined by friction welding. The welding process was carried out under optimized conditions using statistical approach. The study of SM45C is conducted with various combinations of process parameters. Parameter optimization, microstructure and mechanical property correlation are the major contribution of the study. The welded joints were produced by varying spindle revolution speed, friction pressure, upset pressure and burn-off length. Tension tests were applied to welded parts to obtain the strength of the joints. Fracturs properties were additionally obtained experimentally under fluctuated tensile loads. Microstructures using microphotographs were examined in the weld interface and weld region and heat affected zone and base metal and flash zone of welded parts. Finally, Hardness variations in welding zone and base metal were also obtained. Through these tests, the optimum conditions of parameters for ${\phi}20$ SM45C in friction welding were obtained when the friction spindle revolution was 1,950 rpm, the friction pressures was 30 MPs, upset pressures was 50 MPs.

• Journal of Ocean Engineering and Technology
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• v.4 no.1
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• pp.101-109
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• 1990

The friction welding has more technical and economic advantages than the other welding processes. As this welding process has the characteristics such as curtailment of production time, materials, cost reduction, etc., it has been widely used in production of various mechanical components which have complex shapes. So, this paper deals with optimizing the friction welding conditions and analyzing various mechanical properties of the friction welded joints of torsion bar material SUP9A bar to bar. The results obtained are summarized as follows; 1) The quantitative relation between heating time($t_{1}$, sec) and total upset(U, mm)can be obtained. The empirical formula obtained is ; U = 3.29$t_{1}$ + 1.6 2) The tensile strength($\sigma_{t}$, kgf/$mm^{2}$) of friction welding joints as post weld heat treated(PWHT) depends upon heating time($t_{1}$, sec) quantitatively and the empirical formula obtained is ; $\sigma$= -5.1$t_{1}\;^{2}$+44.90$t_{1}$+45.2 3) It is certain that the optimum condition for friction welded joints of SUP9A steel bars of diameter 14.5mm is, considering on various properties such as tensile strength, torsional strength, impact energy and strain of the joints after PWTH ; n = 2000rpm, $P_{1}$=8kgf/$mm^{2}$, $P_{2}$=20kgf/$mm^{2}$, $t_{1}$=4sec, $t_{2}$=3sec 4) The tensile strength, torsional strength and hardness were increased with the increased with the increasing carbon equivalent, but toughness was decreased.

• Journal of Ocean Engineering and Technology
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• v.2 no.2
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• pp.112-121
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• 1988

A study on friction welding of carbon steel bar (SM45C) to chrome molybedenum steel bar(SCM4) is examined experimentally through tensile test, hardness test, microstructure test and fatigue test. so, this paper deals with optimizing the welding concitions and analyzing various mechanical properties about friction welds of SM45C to SCM4 steel bars. The results obtained are summarized as follows; 1) For friction welded joints of SM45C to SCM4 steel bars, the total upset(U)increases linearly with an increase of heating time ($t_{1}$) till 6s. 2) The determined optimum welding conditions are heating time ($t_{1}$)2s, upsetting time($t_{2}$), 3s, heating pressure($p_{1}$), 4kgf/$mm^{2}$(39.2MPa), upsetting pressure($p_{2}$, 8kgf/mm$^{2}$(78.4MPa) and rotating speed(N), 2, 000rpm when the total upset(U) is 3.4mm, resulting in a computed relationship between the joint tensile strength .sigma.$_{t}$ (kgf/mm$^{2}$and the total upset U(mm); .sigma.$_{t}$ =$0.21U^{3}$ - $3.38U^{2}$ +17.03U + 66.00 3) As the elongation is increased more and more, the fracture position becomes away from weld interface and the fractures are similar to those of SM45C. Fracture is taken place on SM45C side. 4) The weld interface of two dissimilar materials is mixed strongly, and the heat affected zone is about 2.0mm at SM45C while about 2.7 mm at SCM4 side. Therefore, the welded zone and heat affected zone are very narrow, comparing with those of the joints welded by the other welding methods. 5) The fatigue strengths at N=10$^{6}$ cycles of SM45C, SCM4 and friction welded joints are 23kgf/$mm^{2}$, 33kgf/$mm^{2}$(220.5 MPa), and 22.5kgf/$mm^{2}$(220.5MPa) respectively, and fracture at friction welded joint takes place at the side of SM45C. 6) The hardness of the friction weld interface is 3 times higher than that of base metal. 7) Fatigue strength of friction welded joint is higher than that of base metal. 8) Notch sensitivity factor of friction welded joint is lower than that of base metal.

• Journal of the Korean Society for Heat Treatment
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• v.29 no.2
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• pp.66-74
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• 2016

In this study, characteristics of TiAl alloy and SCM440 (Cr-Mo steel) have been investigated with the various joining condition by servo motor type friction welder. The experimental factors of friction welder used in this study are spindle revolution, friction speed, and distance, upset speed and distance, respectively. Servo motor type friction welder could be controlled by the level of oil pressure, and it could be performed by position control dependence of electrical energy. Mechanical properties and morphology of welded interface were characterized by various joining condition. This aroused due to the bond strength dependence on friction heat and size of the heat affected zone. Therefore, it is necessary to have enough friction heat and decreased heat affected zone for good friction welding between dissimilar metals. An optimum bond was obtained between TiAl alloy and SCM440 by controlling friction speed and distance. At the spindle revolution 4,000 rpm, friction speed 120 mm/min, friction distance 15 mm, the bond strength was found to be 312 MPa.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.14 no.2
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• pp.79-87
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• 1978

This is an experimental study on friction welding and heat treatment of engine exhaust valve materials whose welding combination is SCr4 as stem to 21-4N as head and SUH3 to 21-4N. In this study, not only the experiments of friction welding under the selected optimum welding condition and the examination of the mechanical properties were carried out, but also the heat treatment of friction welded specimens under the two selected conditions was taken to obtain the better welding character, eliminating the latent stress and the hardness peak which appeared at the welded zones of heat resisting steel(21-4N, SUH3) and low alloyed steel ($SCr_4$) friction weldments. The results obtained by the experiments and consideration in this study are as follows: I) It was experimentally proved quite reasonable that 'speed=3,OOO rpm, heating pressure Pl=8 kg/ mm2, upsetting pressure p, = 20 kg/mm', heating time $t_1$ = 3 see, upsetting time TEX>$t_2$ = 2.5 sec' was selected as the optimum welding condition for friction-welding the engine exhaust valve materials $SCr_4$ to 21-4 Nand SUH 3 to 21-4 N. 2) The results of the previous study and this one on friction welding of such dissimilar materials as SUH 3-SUH 31, SCr 4-SUH 31, SCr 4-SUH 3, SUH 3-CRK 22, SCr4-21-4 Nand SUH3-21-4 N agreed with each other substantially in the friction welding characteristics at welded interface zones. 3) It was also certified quite satisfactory that '600\ulcornerCX30 min. Xroom air cooling' as an optimum heat treatment condition of the friction welded materials SCr 4-21-4 Nand SUH 3-21-4 N was experimentally determined to eliminate the latent stress and the hardness peak at welded zones. 4) About 20% of the tensile strength before heat treatment of friction welded specimens was decreased after heat treatment 600\ulcornerCX30 min. Xair cooling, but the location of fracture was moved from heat affected zone to parent $SCr_4$ & SUH3. 5) Microscopic examination of the weld joints friction-welded and heat-treated under the above mentioned conditions revealed that the weld zone is very narrow and has a fine grained intermixed structure without any welding defects. 6) The above mentioned conditions can be also utilized as friction welding parameters of the other dissimiar materials for engine valve production.