Joining Phenomena Research Articles

Elucidation of dissimilar material joining phenomena on steel and aluminum alloy using hot-wire laser brazing

Elucidation of dissimilar material joining phenomena on steel and aluminum alloy using hot-wire laser brazing

Effects of tensile strength on friction welding condition and weld faying surface properties of friction welded joints between pure copper and austenitic stainless steel

This paper reported the effects of tensile strength on friction welding condition and weld faying surface properties of friction welded joints between pure copper (OFC) and austenitic stainless steel (AISI 304). The joining phenomena and the joint tensile strength at various friction welding conditions were investigated. The maximum temperature of the joint at a friction pressure of 90 MPa was lower than that of 30 MPa. Also, the central portion of the weld interface of the joint with high friction pressure was not joined completely. Hence, it was showed that the joint should be made with a low friction pressure. In addition, the friction torque curve, joint appearance, flash quantity, and axial shortening of joints differed by virtue of the polishing timing at the weld faying surface, and they were influenced by the surface condition of the OFC side before welding. As a conclusion, the good joint with the fracture in the OFC side should be made with a low friction pressure such as 30 MPa, a friction time after the friction torque reached the initial peak such as 3.6 s, and a high forge pressure such as 270 MPa. Furthermore, the weld faying surface of the OFC side should be polished just before welding, and it was suggested.

Influence of Friction Pressure on Microstructure and Joining Phenomena of Dissimilar Joints

The present study investigates the feasibility of using friction welding for the dissimilar materials of stainless steel to high carbon steel. The major process conditions were identified to govern the welding strength and joining phenomena. The welding parameters combination influences the axial shortening in the welds. The friction pressure shows a major role in axial shortening and intermixing zone compared to other parameters. The axial shortening as a weld flash near the joint interface increases with the increase in friction pressure. The width of an intermixing zone among stainless steel and carbon steel grows toward stainless steel from carbon steel with increasing friction pressure. The joining mechanism of dissimilar steels is determined according to the friction stage and upset stage on the thermal behavior and physical properties of the joints.

Metallurgical reaction and joining phenomena in friction welded Al/Fe joints

The continuous drive friction welding of aluminum alloy to stainless steel was investigated in this paper. Microstructural characterization, intermetallic compound (IMC), and mechanical properties of the friction welded Al/Fe joint were studied. Results showed that thermal mechanically affected zone (TMAZ) at the Al side was subjected to both thermal cycling and mechanical force, and grain size was 1–3 μm, and streamlines were more dramatically than at the steel side. In fully dynamic recrystallized 127 zone (FDRZ), microstructure became the fine equiaxed grains, and its width at the steel side was about 5 μm. The local Si enrichment IMC layer was formed at the interface area of Al/Fe joint, and its average thickness was about 300 nm. IMC layer was relatively flat at the steel side, while uneven at the Al side. The hardness reached to the maximum value (395.8 HV) at the steel side in FDRZ, and the average hardness was only 76 HV in heat-affected zone (HAZ) at the Al side. When forge pressure was below 220 MPa, the tensile strength of joint was approximately linearly related to the forge pressure.

Joining phenomena and tensile strength of joint between Ni-based superalloy and heat-resistant steel by friction welding

In order to obtain easily good joint with no crack at the interface between Ni-based superalloy (Ni-SA) and heat-resistant steel (HRS), the investigation of weldability in those material combinations by friction welding method is required. This paper described the joining phenomena and the tensile strength of the friction-welded joint between Ni-SA and HRS. The joining phenomena during the friction process, such as joining behaviour and friction torque, were measured. The effects of friction pressure, friction time, and forge pressure on the joint tensile strength were also investigated, and the characteristics of joints were observed and analysed. The good joint, which had the fracture in the HRS base metal and the tensile strength of its base metal with no crack at the weld interface, could be successfully achieved, although it had the hardened and softened areas at the adjacent region of the weld interface. In conclusion, it was found that the joint should be made with an opportune friction time after the HRS side was transferred to the entire weld interface on the Ni-SA side and with adding high forge pressure such as 360 MPa. Hence, the good joint could be obtained by friction welding method.

Effect of friction welding condition on joining phenomena and mechanical properties of friction welded joint between 6063 aluminium alloy and AISI 304 stainless steel

Dissimilar metal joints have some advantages such as high functionality characteristics for the industrial usage. This paper describes the effect of friction welding condition on joining phenomena, tensile strength, and bend ductility of friction welded joints between Al-Mg-Si alloy (AA6063) and austenitic stainless steel (AISI 304). When joints were made at a friction pressure of 30MPa with a friction speed of 27.5s−1, the upsetting (deformation) occurred at the AA6063 side. The temperature on the weld interface increased with friction time, and it reached to 623K or over at a friction time of 1.5s or longer. When joints were made with a friction time of 1.5s and a forge pressure of 240MPa, all joints had the joint efficiency of approximately 100% and the fracture in the AA6063 base metal. Furthermore, those joints had the bend ductility of 90° in a single direction with no crack at the weld interface and did not have the intermetallic compound (IMC) interlayer on the weld interface. To obtain 100% joint efficiency with good joint, the joint should be made with the following conditions: a high forge pressure such as 240MPa, the opportune friction time that the temperature on the weld interface reached to about 623K or higher.

Effect of friction welding condition on joining phenomena, tensile strength, and bend ductility of friction welded joint between pure aluminium and AISI 304 stainless steel

Aluminium (Al) and stainless steel have such some advantages as high functionalities for the industrial usage. However, the dissimilar joints have severe problems such as generating the intermediate layer consisting of a brittle intermetallic compound (IMC interlayer) during welding process. Friction welding is very useful for making of dissimilar joint. This paper described the effect of friction welding condition on joining phenomena, tensile strength, and bend ductility of friction welded joints between pure Al (CP-Al) and austenitic stainless steel (AISI 304). The joining phenomena during the friction process such as joining behaviour, friction torque, temperature changes at the weld interface, and transitional changes of the weld interface were investigated. The effects of friction time and forge pressure on the tensile strength and bend ductility of joints were also investigated, and the metallurgical characteristics of those were observed. The joint, which had high joint efficiency, the fracture on the CP-Al side with no crack at the weld interface, and no IMC interlayer on the weld interface, could be successfully achieved. Then, the joint should be made with a high forge pressure of 150MPa, the opportune friction time at which the temperature on the weld interface reached about 573K or higher, and those friction welding conditions were suggested for obtaining good joints with high joint efficiency and the bend ductility of 90°.

Joining phenomena and tensile strength of friction welded joint between Ti–6Al–4V titanium alloy and low carbon steel

Dissimilar metal joints (dissimilar joints) have such several advantages as high functionalities for the industrial usage. However, the dissimilar joints have severe problems such as generating the intermediate layer consisting of a brittle intermetallic compound (IMC interlayer) during welding process. Friction welding is very useful for making of dissimilar joint. This paper described the joining phenomena and the tensile strength of friction welded joint between titanium alloy (Ti–6Al–4V) and low carbon steel (LCS). The joining phenomena during the friction process such as joining behavior, friction torque, and temperature changes at the weld interface were measured. The effects of friction pressure, friction time and forge pressure on the joint strength were also investigated, and the metallurgical characteristics of joints were observed and analyzed. Then, the joint, which had 100% joint efficiency, the fracture on the LCS base metal with no crack at the weld interface, and no IMC interlayer on the weld interface, could be successfully achieved. It was suggested that the joint should be made with high friction pressure, opportune friction time to prevent generating of the IMC interlayer, and with high forge pressure in order to achieve completely joining of the weld interface.

座談会「溶接・接合現象における最新の実験観察とシミュレーションを語る」実験観察・シミュレーション究極のゴールと現状課題、改善の方向性

座談会「溶接・接合現象における最新の実験観察とシミュレーションを語る」実験観察・シミュレーション究極のゴールと現状課題、改善の方向性

Mechanical property and joining characteristics of laser direct joining of CFRP to polyethylene terephthalate

This study was performed to investigate the joining possibility and characteristics of the dissimilar joint between carbon fiber reinforced plastics (CFRP) and amorphous polyethylene terephthalate (PET) plastic using a continuous wave (cw) diode laser with a line-shaped beam. Tensile shear test results demonstrated that strong lap joints with a maximum load of 3200 N could be produced under some proper conditions, and base amorphous PET plastic sheet was elongated without fracture. It was confirmed from SEM observation that the dissimilar lap joint was tightly bonded near the joint interface between two materials, and simultaneously integrated by the interdiffusion and mixing process at the joint interface of two materials through rapid melting, solidification and cooling during laser joining. Through high speed video camera observation, the joining phenomena generating in the laser irradiated part during laser joining of CFRP to PET was obviously identified. Consequently, it was revealed that strong dissimilar lap joint of CFRP to engineering plastic could be possible by a direct laser irradiation without adhesive bonds or mechanical fasteners.

Joining phenomena and tensile strength of friction welded joint between pure titanium and low carbon steel

This paper describes the effect of the friction welding condition on the joining phenomena and the tensile strength of friction welded joint between pure titanium (P-Ti) and low carbon steel (LCS). The adjacent region of the weld interface at the P-Ti side was intensely upsetting with accompanied large deformation of itself when the joint had sparkle at both applied friction pressures of 30 and 90MPa, although that of the LCS side was hardly upset. The temperature of the whole weld interface at a friction pressure of 30MPa reached to 1150K or over at a friction time of 3.0s or longer. However, the half radius and centreline portion temperatures of the weld interface at a friction pressure of 90MPa was not reached to 1150K, although the periphery portion of that was reached to its temperature. The central portion of the weld interface at a friction pressure of 90MPa was deformed to a convex shape from the viewpoint of the P-Ti side, although that of 30MPa remained almost flat after when the friction torque reached the initial peak. When the joint was made at a friction pressure of 30MPa, a friction time of 3.0s or longer, and a forge pressure of 270MPa or higher, it achieved 100% joint efficiency and the P-Ti base metal fracture with no crack at the weld interface. However, many joints at friction times of 1.2 and 1.5s fractured at the weld interface, although those achieved 100% joint efficiency, because whole weld interface temperature was below 1150K. On the other hand, many joints at a friction pressure of 90MPa with high forge pressure also fractured at the weld interface, although those achieved 100% joint efficiency, because the weld interface temperature at the half radius and periphery portions was below 1150K. Those joints did not have the intermetallic compound layer at the weld interface. The difference of the fractured portion of the joint in both applied friction pressures was due to the difference between the maximum temperature at the weld interface during the friction process and the deformation amount of the LCS side caused by applied forge pressure. To obtain 100% joint efficiency with the P-Ti base metal fracture with no crack at the weld interface, the joint should be made with high forge pressure, low friction pressure, and with opportune friction time at which the temperature at whole weld interface reached around 1150K.

Joint properties and its improvement of high-tensile strength steel joint by autocompleting friction welding method

This paper describes the improvement of properties of a high-tensile strength steel joint by an autocompleting friction welding method that was developed by the authors. The base metal was high-tensile strength steel of 800 MPa class. The weld faying surface of the fixed specimen had a 10 mm diameter, and the effect of the thickness and that at the bottom of the grooves (groove bottom thickness) for the insert piece on the joining phenomena and joint properties were investigated. The value of a circumferential shear fracture (CSF value) was defined and calculated by the ratio between the theoretical and the actual generated friction torques. When the CSF value was lower than 1, the insert piece had the CSF before the friction torque reached the initial peak. Also, when the CSF value was larger than 1, the insert piece had the CSF after the friction torque reached the initial peak. When the joint was made at the insert thickness of 5 mm with the CSF value of nearly 1, it had 100% joint efficiency although it had the softened region near the weld interfaces. The joint had cracks at the weld interface when it was made with friction pressures of 36 and 120 MPa. However, the joint had no crack at the weld interface when it was made with a friction pressure of 90 MPa. When the joint was made at the insert thickness of 4 mm with the CSF value of nearly 1, it had also 100% joint efficiency although it had the softened region near the weld interfaces. However, the softened region at the weld interface of the joint with the insert thickness of 4 mm was lower than that with 5 mm. Also, this joint had 90° bend ductility with no crack at the weld interface. In conclusion, it was possible to make a joint with no cracks for high-tensile strength steel by an autocompleting friction welding method.

Experimental examination for understanding of transition behaviour of oxide inclusions on gas pressure weld interface: joining phenomena of gas pressure welding

Gas pressure welding method is often applicable for joining of rails and reinforcing steel bars. However, if bonding work is inferior, a large quantity of oxide inclusions remain at the weld interface and those inclusions will cause the weld defects. In the previous study, the morphologies of oxide inclusions were estimated by the observation of the transition behaviour for inclusions on each welding stage during the gas pressure welding. In this study, we traced the morphological change of oxide inclusions and base material in the pressure welding process to clarify the transition behaviour of oxide inclusions. In the first stage, Fe–O type oxide inclusions were mainly deoxidized by carbon, which exists in base material, and the degree of decomposition was influenced by temperature. Furthermore, oxide inclusions, which contain Si and Mn, emerged from outside region of Fe–O type oxide inclusions due to participation of Si and Mn, which exist in base material. In the final stage, almost of oxide inclusions that existed on the weld interface were Si–Mn–O type, and the Si content of these oxide inclusions gradually increased as well, as downsizing of oxide inclusions as welding process advanced.

432 ABS樹脂摩擦圧接の接合現象と継手強度に及ぼす圧接条件の影響

The joining phenomena during the friction process and the joint tensile strength of ABS resin friction welded joint were investigated. When the joint was made with a friction pressure of 0.5MPa or lower, the temperatures at the weld interface during the friction process exceeded 130 ℃. This temperature was higher than that of the glass transition temperature of ABS resin. That is, the temperature at the weld interface of the ABS resin friction welding exceeded the glass transition temperature, of which was differed with the friction welding of various metals. When the joint was made with a friction speed of 4.2s^<-1> and a friction pressure of 0.3MPa or a friction speed of 3.3s^<-1> and a friction pressure of 0.5MPa, it was obtained about 67% joint efficiency. However, the joint efficiency decreased with increasing friction time, and that also decreased with decreasing friction time. The joint efficiencies with other friction pressures were showed with similar change although the friction speed differed. In conclusion, to obtain the higher joint efficiency, the joint should be made with opportune friction speed and friction pressure.

接合自己完了型摩擦圧接した黄銅挿入材と軟鋼との継手における挿入材形状の検討

This paper describes the examination of the insert piece shape for the joint of a low carbon steel (LCS) fixed specimens using a brass insert piece by an autocompleting friction welding method, that method was developed by authors. The weld faying surface of the LCS specimen had a 10mm diameter, and the joint was made with a friction speed of 27.5rps (1650rpm) and a friction pressure of 90MPa. Then, the effect of the thickness and that at the bottom of the grooves (groove bottom thickness) for the brass insert piece on the joining phenomena and joint properties were investigated. The joint, which was made with an insert piece thickness of 4mm and a groove diameter of 11mm, had the circumferential shear fracture during the friction process at the groove bottom thickness of 0.95mm or below. However, some joints did not have the circumferential shear fracture although other joints had its fracture at a groove bottom thickness of 1.15mm or above. The joint efficiency of those joint had scatter, although that increased with increasing the groove bottom thickness and one of the joint had 100% joint efficiency at 1.45mm. That is, the joint, which had reliably the circumferential shear fracture with the 100% joint efficiency, was not obtained at an insert piece thickness of 4mm. To reliably obtain the joint which had the circumferential shear fracture with the 100% joint efficiency, the effect of the insert piece thickness was investigated. The joint efficiency increased with increasing insert piece thickness, and the scatter of that was decreased. When the joint was made with an insert piece thickness of 8mm and a groove diameter of 11mm, those had reliably the circumferential shear fracture with the 100% joint efficiency at the groove bottom thickness of 0.70 and 0.75mm. Also, when the joint was made with an insert piece thickness of 6mm and a groove diameter of 12mm, the joint had also reliably the circumferential shear fracture at the groove bottom thickness of 0.70mm. Therefore, a joint with 100% joint efficiency, which was made with the LCS with the brass insert piece, should be made with opportune brass insert piece shape of that thickness, the groove diameter, and the groove bottom thickness. In conclusion, a dissimilar joint was able to make by an autocompleting friction welding method.

412 A1070/OFC摩擦圧接の接合現象と継手強度に及ぼす摩擦時間とアプセット圧力の影響

412 A1070/OFC摩擦圧接の接合現象と継手強度に及ぼす摩擦時間とアプセット圧力の影響

413 A5052接合自己完了型摩擦圧接継手の性能改善

This paper describes about the joint properties and its improvement of A5052 autocompleting friction welded joint, that welding method was developed by authors. The fixed specimen had the weld faying surface of 10mm with the overhanging length of 15 or 5mm, and the joint was made with a friction speed of 27.5s^<-1> and a friction pressure of 60 or 80MPa. Then, the effect of the bottom of the grooves (groove bottom thickness) for the insert piece on the joining phenomena and joint properties were investigated. As a conclusion, the joint had 100% joint efficiency with the base metal fracture at the groove bottom thickness of 1.4mm and the fixed specimen overhanging length of 5mm which was made at a friction pressure of 80MPa, although it did not achieve 100% joint efficiency at a friction pressure of 60MPa.

410 A6061/AC8A摩擦圧接の接合現象に及ぼす接合端面形状の影響

410 A6061/AC8A摩擦圧接の接合現象に及ぼす接合端面形状の影響

Effect of friction pressure on joining phenomena of friction welds between pure titanium and pure copper

This paper describes the effect of friction pressure on the joining phenomena of friction welds between pure titanium (P-Ti) and pure copper (OFC). When the joint was made at a friction pressure of 60 MPa or lower, the OFC side had deformation from the contact of both weld faying surfaces. Then the joint had generated sparkle from the P-Ti side with increased friction time. The peripheral portion of the P-Ti side had large deformation and was intensely upset when the joint had sparkle. On the other hand, the joint did not have sparkle on the P-Ti side when it was made at a friction pressure of 75 MPa or higher. The deformation of the OFC side was large and was intensely upset, although the P-Ti side was hardly deformed. The joining phenomena had dissimilarity because the difference of the yield stress for each material depended on the temperature in the friction process.

430 純Ti/OFC摩擦圧接の接合現象(溶接・接合のプロセスと評価(1),ものづくりにおける基礎研究と先端技術の融合)

The joining phenomena during the friction process of pure titanium (Ti) and pure copper (OFC) friction welding was investigated. When the joint was made at a friction pressure of 60MPa or lower, the OFC side was deformed from both weld faying surfaces contacting. Then, the joint generated the sparkle from the Ti side with increasing friction time. The peripheral portion of the Ti side was heavily deformed and intensely upset when it had the sparkle. On the other hand, the joint did not have the sparkle of the Ti side when it was made at a friction pressure of 75MPa or higher. The deformation of the OFC side was large and intensely upset. The fact that the joining phenomena had dissimilarity was due to the difference of the yield strength at the temperature in the friction process.