Continuous Drive Friction Welding Machine Research Articles

The effects of the welding parameters on the microstructure and mechanical properties of the friction welded AZ91 Mg alloy.

The AZ91T5 Mg alloy was bonded by friction welding process. The welding process was carried out by continuous drive friction welding machine. The friction load, time and speed are used as friction welding parameters, and the effects of these parameters on the microstructure and mechanical properties of the welding interface were investigated. Characterization of welding interface microstructure and fractured surfaces of joints was carried out by optical microscopy and scanning electron microscopy. Microstructural investigations revealed that the welding interfaces have a smooth and continues morphology. The micro hardness and shear strength of matrix and the welding interfaces were measured in order to determine the mechanical properties of joints. The results showed that the welding interfaces have higher hardness than the matrix and the shear strengths of welding interfaces increase with increasing pressure and speed while time has different effect.

Characteristics of Friction Welding Between Solid Bar of 6061 Al Alloy and Pipe of Al-Si12CuNi Al Cast Alloy

This paper describes the characteristics of friction welding between a solid bar of 6061 Al alloy and a pipe of Al-Si12CuNi (AC8A) Al cast alloy. When the joint was made by a continuous drive friction welding machine (conventional method), the AC8A portion of the joint showed heavy deformation and the AA6061 showed minimal deformation. In particular, the joint could not be successfully made with following conditions, because AC8A pipe side crushed due to insufficient friction heat or high pressure: a short friction time such as 0.3 s, high friction pressure such as 100 MPa, or high forge pressure such as 150 MPa. The heavy deformation of AC8A side was caused by increasing friction torque during braking. To prevent braking deformation until rotation stops, a joint was made by a continuous drive friction welding machine that has an electromagnetic clutch. When the clutch was released, the relative speed between both specimens simultaneously decreased to zero. When the joint was made with friction pressure of 25 MPa, friction time of 0.3 s, and forge pressure of 125 MPa, the joining could be successfully achieved and that had approximately 16% efficiency. In addition, when the joint was made with friction pressure of 25 MPa, friction time of 0.7 s, and forge pressure of 125 MPa, it had approximately 54% efficiency. However, all joints showed the fracture between the traveled weld interface and the AC8A side, because the weld interface traveled in the longitudinal direction of AC8A side from the first contacted position of both weld faying surfaces. Hence, it was clarified that the friction welding between a solid bar of AA6061 and a cast pipe of AC8A was not desirable since the traveling phenomena of the weld interface were caused by the combination of the shapes of the friction welding specimens.

Friction welding technique and joint properties of thin-walled pipe friction-welded joint between type 6063 aluminum alloy and AISI 304 austenitic stainless steel

The joint characteristics of thin-walled pipe friction-welded joint between AA6063 aluminum alloy (A6063) and AISI 304 stainless steel (SUS304) were investigated. The pipe had a thickness of 1.5 mm, and the joint was made with a friction speed of 27.5 rps and a friction pressure of 30 MPa. The joint, which was made by a continuous drive friction welding machine, had heavy deformation on the A6063 side during braking. To prevent deformation until rotation stop with braking, the joint was made by a technique in which the relative speed between both specimens instantly decreased to 0 when the setting friction time was finished, and consequently, the joining could be successfully achieved. The joint with a friction pressure of 30 MPa and a friction time of 0.4 s did not have the intermetallic compound (IMC) layer (interlayer) at the weld interface, although that with a friction time of 1.6 s had it. However, the joint with a forge pressure of 150 MPa had the A6063 side buckling. Moreover, the joint efficiency of the joint with flash was higher than that of the joint without flash because the inner flash of A6063 was stuck to the inner surface of the SUS304 side. Therefore, the joint should be made with the opportune friction time without the IMC interlayer and with the opportune forge pressure without buckling, and the accurate joint efficiency should be evaluated without flash.

Joint properties and their improvement of AISI 310S austenitic stainless steel thin walled circular pipe friction welded joint

This paper describes the joint properties and their improvement in thin walled circular pipe friction welded joint for an AISI 310S austenitic stainless steel. Pipes were welded with the combination of the same thickness and outer diameter by a continuous drive friction welding machine that has an electromagnetic clutch. Then, when the clutch was released, the relative speed between both specimens instantly decreased to zero. When the joint with a pipe thickness of 1.50mm was made at a friction pressure of 120MPa, the joining could be successfully achieved and that had 100% efficiency with the base metal fracture. However, the joining became difficult with decreasing pipe thickness, and it was not successful at a pipe thickness of 0.50mm. On the other hand, when the joint with a pipe thickness of 0.50mm was made at a friction pressure of 30MPa, the joining could be successfully achieved, although that did not have 100% efficiency. Then, when the joint was made under a friction time of 0.6s, i.e. the friction torque reached just after the initial peak, and a forge pressure of 60MPa, it had 100% efficiency with the base metal fracture. However, when that was made with high forge pressure such as 120MPa, the joining could not be achieved because the adjacent region of the weld interface had heavy buckling. To obtain the successful joining and 100% joint efficiency with the base metal fracture for the thin walled circular pipe, the joint should be made with opportune friction welding condition as follows: low friction pressure, a friction time of just after the initial peak of the friction torque, and a forge pressure of double value of a friction pressure.

Fatigue behaviour of friction welded medium carbon steel and austenitic stainless steel dissimilar joints

This paper reports the fatigue behaviour of friction welded medium carbon steel–austenitic stainless steel (MCS–ASS) dissimilar joints. Commercial grade medium carbon steel rods of 12mm diameter and AISI 304 grade austenitic stainless steel rods of 12mm diameter were used to fabricate the joints. A constant speed, continuous drive friction welding machine was used to fabricate the joints. Fatigue life of the joints was evaluated conducting the experiments using rotary bending fatigue testing machine (R=−1). Applied stress vs. number of cycles to failure (S–N) curve was plotted for unnotched and notched specimens. Basquin constants, fatigue strength, fatigue notch factor and notch sensitivity factor were evaluated for the dissimilar joints. Fatigue strength of the joints is correlated with microstructure, microhardness and tensile properties of the joints.

Some experimental investigations on friction welded stainless steel joints

Friction welding is a solid state process and it is best suited for joining similar and dissimilar materials. It circumvents the problems associated with the traditional fusion joining processes. Because of the superior properties, it is pertinent to use stainless steels in various automotive, aerospace, nuclear, chemical and cryogenic applications. This present study emphasizes on joints of two types of industrially important stainless steels such as austenitic and ferritic stainless steels. The present study utilized a continuous drive friction welding machine to process similar joints. Cylindrical specimens of austenitic stainless steel and ferritic stainless steel of similar composition and shape (equal diameter and length) were used in this study. The processed joints were tested through uni axial tension test, impact test and hardness test. Microstructural studies were also carried out. The characteristics such as tensile strength, toughness, hardness across the joint zone and microstructural aspects exhibited by friction processed joints were compared to the respective parent materials. Joints processed by this method exhibited better properties when compared to the fusion processed joints.

Properties and improvement of super fine grained steel friction welded joint

This paper describes friction welded joint properties of super fine grained steel (SFGS) and discusses improvements in these joint properties. The average grain size diameter of the SFGS base metal is ∼0·6 μm, and its ultimate tensile strength is 660 MPa. The joint, made by a continuous drive friction welding machine (conventional method), fractured at the welded interface even though it possessed 100% joint efficiency. This was due to both the coarsening of the grain size and the softening of the welded interface with its adjacent region caused by heat input during braking times. The authors developed a joining method using a continuous drive friction welding machine that has an electromagnetic clutch to eliminate heat input during braking time, which was called the 'low heat input friction welding method' (LHI method). The joint obtained by the LHI method had the same tensile strength as the base metal at the friction time when the friction torque reached the initial peak. That is, the joint obtained 100% joint efficiency and fractured at the base metal, although the adjacent region of the welded interface softened only slightly. The grain size of this joint was smaller than that obtained by the conventional method. It was clarified that the optimum friction welded joint of the SFGS could be obtained by the LHI method in comparison with the conventional method.

Effect of friction welding conditions on mechanical properties of A5052 aluminium alloy friction welded joint

The present paper describes the mechanical properties of Al–Mg aluminium alloy (A5052) friction welded joints. Two types of A5052 with different tensile properties were used, namely, H112 base metal with 188 MPa tensile strength and H34 with 259 MPa tensile strength. Similar metal specimens were joined using a continuous drive friction welding machine with an electromagnetic clutch to prevent braking deformation. That is, the joints were welded using the 'low heat input' friction welding method developed by the present authors, in which the heat input is lower than in the conventional method. An A5052–H112 joint produced using a friction speed of 27·5 s−1, friction pressure of 30 MPa, friction time of 2·0 s (just after the initial peak torque), and forge pressure of 60 MPa had approximately 95% joint efficiency. It fractured at the welded interface and in the A5052–H112 base metal. To improve the joint efficiency, an A5052–H112 joint was produced at a forge pressure of 75 MPa, which was the same as the yield strength of the A5052–H112 base metal. It had 100% joint efficiency and fractured in the A5052–H112 base metal. In contrast, an A5052–H34 joint was made using a friction speed of 27·5 s−1, friction pressure of 90 MPa, friction time of 0·3 s (just after the initial peak torque), and forge pressure of 180 MPa. It had approximately 93% joint efficiency and fractured in the A5052–H34 base metal. This joint also had a softened region at the welded interface and in the adjacent region. To improve the joint efficiency, an A5052–H34 joint was made at a forge pressure of 260 MPa, which was the same as the ultimate tensile strength of the A5052–H34 base metal. Although this joint had a slightly softened region at its periphery, it had approximately 93% joint efficiency. The failure of the A5052–H34 joint to achieve 100% joint efficiency is due to a slight softening at the periphery and the difference in the anisotropic properties of the A5052–H34 base metal between the longitudinal and radial directions.

Effect of friction welding parameters on mechanical and metallurgical properties of ferritic stainless steel

Friction welding is one of the most economical and highly productive methods in joining similar and dissimilar metals. It is widely used in the automotive and aerospace industrial applications. Ferritic stainless steel (AISI430) is normally difficult to weld by fusion methods, due to the associated problems such as grain growth and retained austenite content. Such problems can be alleviated by the friction joining process. The present study utilized a continuous drive friction welding machine to join cylindrical specimens of ferritic stainless steel of similar composition and shape (equal diameter and length). The processing parameters such as friction pressure, friction time, upsetting pressure and upsetting time were changed in order to understand the role of parameters on the strength related aspects of friction processed joints. The joints were subjected to mechanical testing methods such as the uni-axial tension test, and charpy ‘v’ notch impact tests. The micro hardness variation across the joint zone was determined. Micro structural studies were also carried out. The characteristics such as tensile strength, toughness and microstructural aspects exhibited by friction processed joints were compared to parent materials.

Effect of friction welding conditions and aging treatment on mechanical properties of A7075-T6 aluminium alloy friction joints

This article describes the effect of friction welding conditions and aging treatment on the mechanical properties of type 7075-T6 aluminium alloy (A7075) friction welded joints. A7075 was joined by using a continuous drive friction welding machine with an electromagnetic clutch in order to prevent braking deformation during as rotation speed decreases. That is, it was welded by using the 'Low Heat Input Friction Welding Method' (LHI method) developed by the authors, in which heat input is lower than in the conventional method. The maximum joint efficiency at a friction pressure of 30 MPa was approximately 25%, and that at 90 MPa was approximately 64%. These joints were made without forge pressure. The low joint efficiency was due to the existence of non-joined regions at the welded interfaces. However, the welded joint had approximately 82% joint efficiency when the friction time was 0·5 s at a friction pressure of 90 MPa with a forge pressure of 180 MPa. The welded joint softened at the welded interface and its adjacent region. It had approximately 90% joint efficiency after aging for 730 days at room temperature (natural aging). It also had approximately 95% joint efficiency after aging for 48 h at 393 K (120°C), and had no softened region at the welded interface. The heat input of the welded joint with the LHI method could be decreased to approximately 50% of that with the conventional method. The LHI method has several advantages for A7075 friction welding; less heat input than with the conventional method, and light post-weld processing (machining, etc.) because the flash can be minimised.

Improving Joint Properties of Friction Welded Joint of High Tensile Steel

This report describes the improvements in the joint properties of friction welded joint of 780MPa class high tensile steel. Welded joint made by a continuous drive friction welding machine, the conventional method, had not obtained 100% joint efficiency despite applying forge pressure. This was due to the softening of the welded interface zone for heat input during braking times. Therefore, we developed a continuous drive friction welding machine with an electromagnetic clutch to prevent heat input during braking time. We proposed the process as “The Low Heat Input Friction Welding Method (the LHI method).” In this case, the joint had the same tensile strength as the base metal at friction time when the friction torque reached the initial peak torque. That is, the welded joint obtained 100% joint efficiency by using only the friction stage up to the initial peak torque without the forge (upsetting) stage, despite the existence of a slightly softened region adjacent to the welded interface. Furthermore, the softened region was hardly generated when this joint was made by applying forge pressure at the initial peak torque. In conclusion, a welded joint of high tensile steel made by only the friction stage of the LHI method had excellent joint properties. The LHI method has a lot of advantages for joining such materials as super fine grain steel with which conventional fusion welding processes have difficulty.

低入熱摩擦圧接法による中・高炭素鋼継手の引張強度に及ぼす摩擦時間，摩擦圧力の影響

This report describes the effect of friction time and friction pressure on tensile strength of carbon steel welded joint by a low heat input friction welding method (LHI method) that was developed by authors. Medium (0.35%) and high (0.55%) carbon steel joints were made by friction speed of 27.5s-1 through a continuous drive friction welding machine with an electromagnetic clutch in order to prevent braking deformation during rotation stop.The experiments produced the following summarized results.(1) Medium carbon steel joint did not obtain the same tensile strength as that of the base metal, and the fracture occurred at the welded interface when it was made at friction time up to the initial torque by friction pressure of 30MPa. However, the joint obtained the same tensile strength as that of the base metal, and the fracture occurred at the base metal when it was made at friction time up to the initial torque by 90MPa.(2) Medium carbon steel joint by 30MPa fractured at the welded interface due to the unjoined region, which was produced at the peripheral region of the welded interface during friction process. The unjoined region had not produced with increasing friction pressure.(3) High carbon steel joint did not obtain the same tensile strength as that of the base metal, and the fracture occurred at the welded interface when it was made at friction time up to the initial torque by 30 and 90MPa.(4) High carbon steel joint fractured at the welded interface due to the quench crack, which was produced during cooling stage after welding. The quench crack reduced with increasing friction pressure. However, the joint by high friction pressure (300MPa) did not obtain the same tensile strength as that of the base metal, and it fractured at the base metal, because the center portion at the welded interface hardly joined after the initial torque.

Continuous Drive Friction Welding Studies on AISI 304 Austenitic Stainless Steel Welds

An attempt has been made to study the friction welding characteristics of an austenitic stainless steel AISI 304 employing a continuous drive friction welding machine. The central region in some of the welds exhibited abnormal grain growth. Optimization studies revealed that the optimum parameters depend on the property of interest. In general, friction welds exhibited lower notch tensile strength and impact toughness than the parent metal due to aligned microstructure features. An inverse relationship has been observed between notch tensile strength and impact toughness.

５０５２アルミニウム合金／純チタン摩擦圧接継手の機械的性質に及ぼすインサートメタルの影響

5052 aluminum alloy to pure titanium were friction welded using a continuous drive friction welding machine. Effect of using an insert metal on the microstructures and mechanical properties of the dissimilar friction welded joint was investigated. Friction welded joints without insert metal were observed compound layer and the thickness of intermetallic compound layer were irregular and thick. Friction welded joint with insert metal, its compound layer became thin and generated comparatively evenly. In spite of the existence in the friction welding of the use of the insert metal, the hardness of compound layer of both welded joints showed higher than those of the both base metals. Tensile strength of welded joint without insert metal showed 78% of 5052 aluminum alloy and it's fractured at weld interface. But, in case of welded joint using an insert metal, the tensile strength showed 92% of 5052 aluminum alloy. The elongation of welded joints with insert metal was improved. All the welded joints with insert metal were fractured at softened area of heat affected zone of 5052 aluminum alloy side in tensile test.

515 細粒鋼の摩擦圧接における継手強度

This report describes the joint strength of fine grained steel (FGS) friction welded joints by using the low heat input friction welding method (LHI method) which was developed by authors. The FGS base metals were joined by using the continuous drive friction welding machine with an electromagnetic clutch in order to prevent braking deformation during rotation stop. It was clarified that the friction welded joints with 100% joint efficiency could be obtained by using only the friction stage up to initial torque without the forge (upsetting) stage. That is, the joint tensile strength of the friction welded joints was obtained at the time that the friction torque reached the initial torque. In addition, the joint welded by the LHI method did not cause softening and the grain growth in the heat affected zone. As a conclusion, the LHI method without the forge stage to the FGS base metal welds provides the advantages of less burn-off, less burr, non-softening and less grain growth.

An Approach to the Design Analysis for Continuous Drive Friction Welding Machine

Friction welding (F.W) is a process to successfully join a wide variety of similar and dissimilar metal rods with high energy efficiency. Various ranges of the F. W. machines are now in use in various parts of the world. In India, some automobile manufacturing industries use imported Friction Welding machines. The indegenous machines are yet to be developed, this article deals with the design analysis and scope of indegenous development of Continuous Drive F. W. machines.