1.6mm, as shown in Fig. 6(a). With

1.6mm, as shown in Fig. 6(a). With higher upset pressure, more plastic aluminum alloy is squeezed out, decreasing the softened area of joint. The softened area thickness of sample 3 is approximately 1.9mm. The wider softened region is obtained under long friction time due to more friction heat that promotes the overaging phenomenon of Al alloy. Similar to the diffusion zone, the thickness of the softened area is larger under long friction time and low upset pressure within the range of welding parameters. Nevertheless, the microhardness of steel side is nearly not changed due to its high strength.3.4.2. Tensile strength The effects of upset pressure and friction time on joint strength are shown inFig.7(a) and(b).AspresentedinFig.7(a), thetensile strength of joint with friction time of 1s increases with increasing upset pressure. Compared with the joint strength curve in Fig. 7(b), the effect of upset pressure on tensile strength is more significant than that of friction time, similar to the research by Muralimohan et al. [12]. Obviously, the enlargement of upset pressure within limits improves the joint strength effectively. However, when the upset pressure exceeds 220MPa, thereisadecreased trendinthejoint strength.Thehigh upset pressurewithinlimitswillmaketheorganizational structurearoundthe interface tighter and can eliminate flaw, as presented in Fig. 5. By the observation of fracture structure, a better metallurgical bonding is realized in sample 2 under high upset pressure. Though the diffusion zone may decrease, the high upset pressure can effectively promote the bonding of two materials. Fig. 7(b) shows the influence of friction time on joint strength. With friction time of 1s, the maximum tensile strength of the joint can increase up to 304MPa that is 88 % of the 6061 aluminum alloy strength. Also, we can observe that when friction time is below 1s, the joint strength increases with friction time increasing. Short friction time willresult in insufficient friction heat that serves for atomic diffusion, restricting the metallurgical bonding between steel and aluminum alloy. However, the tensile strength of the Al/steel joint under the upset pressure of 220MPa decreases slightly with increasing friction time over 1s. Long friction time will bring about the excessive formation of IMCs, which may be the cause of the flaw at the interface. In general, theformationofbrittleIMCscanberestricted bycontrolling heat input. Friction welding, as a solid phase technique, can make an effective control of heat input. To obtain an excellent metallurgical bonding, it is of great significance to restrict the excessive formation of IMCs by controlling the diffusion of atoms under the optimized welding parameters with highupset pressure andlow friction time. Nevertheless, the interface microstructure is inhomogeneous along the radial direction as proved by Dong et al. [25], it is impossible to make the metallurgical bonding effective at the overall interface. To promote the metallurgical bonding in the center region of the weld interface by increasing friction time, the periphery region may generate excessive brittle IMCs that is detrimental to the joint strength, otherwise the center region will be unbonded.3.4.3. Bend ductility To clarify the joint properties in detail, the joints are bent by three point bending tests. As presented in Fig. 7(a) and (b), the bending properties of joints under different welding parameters show the same tendency as tensile strength. Figs. 8 and 9 show the appearances of joints after bending tests. The joints welded at different parameters fracture at the interfaceafter bending different angles. The joint welded withupsetpressureof220MPaandfrictiontimeof1scanbebentto80 degrees, as shown in Fig. 8(b). However,asshowninFig.8(a),thejointweldedwithupsetpressure of 120MPa will crack after bending to 33 degrees. The unbonded

結果 (繁體中文) 1:

1.6mm, as shown in Fig. 6(a). With higher upset pressure, more plastic aluminum alloy is squeezed out, decreasing the softened area of joint. The softened area thickness of sample 3 is approximately 1.9mm. The wider softened region is obtained under long friction time due to more friction heat that promotes the overaging phenomenon of Al alloy. Similar to the diffusion zone, the thickness of the softened area is larger under long friction time and low upset pressure within the range of welding parameters. Nevertheless, the microhardness of steel side is nearly not changed due to its high strength.
3.4.2. Tensile strength The effects of upset pressure and friction time on joint strength are shown inFig.7(a) and(b).AspresentedinFig.7(a), thetensile strength of joint with friction time of 1s increases with increasing upset pressure. Compared with the joint strength curve in Fig. 7(b), the effect of upset pressure on tensile strength is more significant than that of friction time, similar to the research by Muralimohan et al. [12]. Obviously, the enlargement of upset pressure within limits improves the joint strength effectively. However, when the upset pressure exceeds 220MPa, thereisadecreased trendinthejoint strength.Thehigh upset pressurewithinlimitswillmaketheorganizational structurearoundthe interface tighter and can eliminate flaw, as presented in Fig. 5. By the observation of fracture structure, a better metallurgical bonding is realized in sample 2 under high upset pressure. Though the diffusion zone may decrease, the high upset pressure can effectively promote the bonding of two materials. Fig. 7(b) shows the influence of friction time on joint strength. With friction time of 1s, the maximum tensile strength of the joint can increase up to 304MPa that is 88 % of the 6061 aluminum alloy strength. Also, we can observe that when friction time is below 1s, the joint strength increases with friction time increasing. Short friction time will
result in insufficient friction heat that serves for atomic diffusion, restricting the metallurgical bonding between steel and aluminum alloy. However, the tensile strength of the Al/steel joint under the upset pressure of 220MPa decreases slightly with increasing friction time over 1s. Long friction time will bring about the excessive formation of IMCs, which may be the cause of the flaw at the interface. In general, theformationofbrittleIMCscanberestricted bycontrolling heat input. Friction welding, as a solid phase technique, can make an effective control of heat input. To obtain an excellent metallurgical bonding, it is of great significance to restrict the excessive formation of IMCs by controlling the diffusion of atoms under the optimized welding parameters with highupset pressure andlow friction time. Nevertheless, the interface microstructure is inhomogeneous along the radial direction as proved by Dong et al. [25], it is impossible to make the metallurgical bonding effective at the overall interface. To promote the metallurgical bonding in the center region of the weld interface by increasing friction time, the periphery region may generate excessive brittle IMCs that is detrimental to the joint strength, otherwise the center region will be unbonded.
3.4.3。彎曲延展性為了闡明詳細接頭性能，接頭是通過三點彎曲試驗彎曲。正如圖7（a）和（b）在圖1中。，下二FF erent接頭焊接參數的彎曲性能顯示出相同的傾向如拉伸強度。圖 圖8和9示出彎曲試驗後接頭的外觀。在interfaceafter在二FF erent參數斷裂焊接接頭彎曲二FF erent角度。接頭焊接withupsetpressureof220MPaandfrictiontimeof1scanbebentto80度，如圖8（b）所示。然而，asshowninFig.8（a）中，120MPa的thejointweldedwithupsetpressure將彎曲到33度後破裂。無粘結

結果 (繁體中文) 2:

1.6 毫米，如圖 6（a）所示。隨著壓壓越高，更多的塑膠鋁合金被擠出，減少了接頭的軟化面積。樣品3的軟化面積厚度約為1.9mm。由於摩擦熱較多，導致鋁合金超老化現象，在長時間摩擦下獲得較寬的軟化區域。與擴散區類似，在長時間摩擦和焊接參數範圍內的低失壓下，軟化面積的厚度較大。然而，鋼側的微硬度由於其高強度而幾乎沒有改變。
3.4.2. 拉伸強度 在圖7（a）和（b）中顯示了壓點壓力和摩擦時間對關節強度的影響。與圖7（a）所示，與摩擦時間為1s的關節的抗性強度隨著抗干擾壓力的增加而增加。與圖7（b）中的關節強度曲線相比，擾壓對拉伸強度的影響比摩擦時間的影響更為顯著，這與Muralimohan等人的研究相似[12]。顯然，在限度內增大壓力，有效地提高了關節強度。然而，當壓壓超過220MPa時，關節強度呈下降趨勢。如圖5所示，高顛簸壓力會使組織結構在介面周圍更加緊密，並消除缺陷。通過對斷裂結構的觀察，在高失壓下，樣品2實現了更好的冶金粘結。雖然擴散區可能減小，但高失壓可以有效地促進兩種材料的粘接。圖7（b）顯示了摩擦時間對關節強度的影響。摩擦時間為 1s 時，接頭的最大拉伸強度可增加到 304MPa，即 6061 鋁合金強度的 88%。此外，我們可以觀察到，當摩擦時間低於1s時，關節強度隨著摩擦時間的增大而增加。摩擦時間短
導致摩擦熱不足，作用於原子擴散，限制了鋼和鋁合金之間的冶金粘結。然而，在220MPa的抗壓下，Al/鋼接頭的拉伸強度略有下降，摩擦時間超過1。長時間的摩擦會導致ImCs的過度形成，這可能是導致介面缺陷的原因。一般來說，通過控制熱輸入，可以限制脆性IMCs的形成。摩擦焊接作為一種固相技術，可以有效地控制熱輸入。為了獲得優良的冶金粘結，在高幹擾壓力和低摩擦時間優化焊接參數下控制原子的擴散，對限制ImCs的過度形成具有重要意義。然而，介面微觀結構在徑向上是不均勻的，正如Dong等人所證明的[25]，不可能使冶金粘結在整體介面上有效。通過增加摩擦時間來促進焊接介面中心區域的冶金粘接，週邊區域可能產生過度脆性ImCs，從而損害接頭強度，否則中心區域將無粘結。
3.4.3. 彎曲延展性為了詳細闡明接頭的特性，通過三點彎曲試驗彎曲了接頭。如圖7（a）和（b）所示，不同焊接參數下接頭的彎曲特性與拉伸強度呈相同的趨勢。圖 8 和圖 9 顯示了彎曲測試後關節的外觀。不同參數焊接的接頭在彎曲不同角度後在介面處斷裂。與220MPa的擾壓和摩擦時間1scanbebentto80度的焊接，如圖8（b）所示。然而，如圖8（a），120MPa的接頭壓壓在彎曲到33度後會破裂。未粘合

結果 (繁體中文) 3:

1.6mm，如圖6（a）所示。鐓粗壓力越大，擠壓出的塑性鋁合金越多，接頭軟化面積越小。試樣3的軟化區厚度約為1.9mm。在長時間的摩擦下，由於摩擦熱的新增，鋁合金的過時效現象加劇，軟化區變寬。與擴散區相似，在焊接參數範圍內，摩擦時間長、鐓粗壓力低時，軟化區厚度較大。但由於鋼的高强度，鋼側的顯微硬度幾乎沒有變化。
3.4.2條。抗張強度-頂鍛壓力和摩擦時間對接頭强度的影響如圖7（a）和（b）所示。如圖7（a）所示，摩擦時間為1s的接頭抗張強度隨頂鍛壓力的新增而新增。與圖7（b）中的接頭强度曲線相比，鐓粗壓力對抗拉强度的影響比摩擦時間的影響更大，與Muralimohan等人的研究相似。[12]是的。顯然，在一定範圍內增大頂鍛壓力可以有效地提高接頭强度。然而，當鐓粗壓力超過220MPa時，接頭强度有下降趨勢，高鐓粗壓力越小，介面附近的組織結構越緊密，可以消除飛邊，如圖5所示。通過對斷裂組織的觀察，在高鐓粗壓力下，試樣2實現了較好的冶金結合。儘管擴散區可能减小，但高的鐓粗壓力可以有效地促進兩種資料的結合。圖7（b）顯示了摩擦時間對接頭强度的影響。摩擦時間為1s時，接頭最大抗拉强度可提高304MPa，為6061鋁合金强度的88%。當摩擦時間小於1s時，接頭强度隨摩擦時間的新增而新增。摩擦時間短
導致摩擦熱不足，導致原子擴散，限制鋼與鋁合金之間的冶金結合。然而，在220MPa的鐓粗壓力下，鋁/鋼接頭的抗拉强度隨著摩擦時間的新增而略有下降，摩擦時間過長會導致IMCs的過度形成，這可能是介面處產生裂紋的原因。一般來說，通過控制熱量輸入，可以嚴格控制熱量輸入。摩擦焊接作為一種固相科技，可以有效地控制熱輸入。為了獲得良好的冶金結合，在高頂鍛壓力和低摩擦時間的優化焊接參數下，通過控制原子擴散來限制IMCs的過度形成具有重要意義。然而，正如Dong等人所證明的，介面微觀結構沿徑向是不均勻的。[25]，不可能使整個介面上的冶金結合有效。為了通過新增摩擦時間來促進焊縫介面中心區域的冶金結合，邊緣區域可能會產生過多的脆性IMCs，這對接頭强度不利，否則中心區域將被剝離。
3.4.3條。為了詳細闡明節點的彎曲延性，對節點進行了三點彎曲試驗。如圖7（a）和（b）所示，不同焊接參數下接頭的彎曲效能與抗拉强度的趨勢相同。無花果。8和9顯示彎曲試驗後的接頭外觀。不同參數焊接的接頭在不同角度彎曲後介面處斷裂。上升壓力為220mpa，摩擦時間為1的焊接接頭應彎曲至80度，如圖8（b）所示。然而，如圖8（a）所示，在彎曲到33度後，上升壓力為120MPa的焊縫將開裂。未粘合的