共查询到17条相似文献,搜索用时 171 毫秒
1.
搅拌摩擦焊中动态再结晶及硬度分布的数值模拟 总被引:3,自引:0,他引:3
使用率相关弹粘塑性本构模型模拟了搅拌摩擦焊接过程,并着重研究了过程参数对搅拌摩擦焊接动态再结晶过程以及搅拌区内材料硬度的影响.结果表明,在搅拌区内焊接构件上、下表面沿垂直于焊缝方向的硬度分布规律不同.焊接构件顶部材料的硬度分布符合实验得到的结果,即焊缝中心线附近材料硬度较低,热力影响区外材料硬度逐渐升高并最终达到母材的硬度;但是在焊接构件下表面并不显示这一硬度分布规律.搅拌区内材料的硬度与搅拌头转速无明显关系,但随焊速的增加而增加.焊接构件中部材料的晶粒尺寸大于焊接构件底部材料的晶粒尺寸,且搅拌区内晶粒尺寸随搅拌头转速的增加趋于均匀. 相似文献
2.
3.
4.
采用完全热力耦合模型对搅拌摩擦焊接过程进行模拟,并详细分析了搅拌摩擦焊接过程中的材料流动形式.结果表明,模型可以成功预测搅拌摩擦焊接过程材料流动和温度分布情况.通过对搅拌头周围材料流动的研究,分析了搅拌摩擦焊接过程中飞边现象形成的主要原因.研究了搅拌摩擦焊接构件不同厚度上材料的三维流动形式,通过与二维情况的比较证实,二维情况下的材料流动数值模拟结果对应于搅拌摩擦焊接构件靠近下表面部分的材料流动情况.从等效塑性应变的分布也能证实搅拌头轴肩对靠近上表面的材料行为具有明显影响,而对下表面附近材料行为影响较弱,从而说明二维情况对应三维情况靠近下表面的部分. 相似文献
5.
接触模型对搅拌摩擦焊接数值模拟的影响 总被引:4,自引:0,他引:4
在完全热力耦合搅拌摩擦焊接数值模型中采用两种接触模型--经典的Coulomb接触模型和修正的Coulomb接触模型,模拟了搅拌摩擦焊接过程,以分析不同接触模型对搅拌摩擦焊接过程数值模拟的影响.结果表明,对于低转速的搅拌摩擦焊接,两种模型的预测结果区别不大;但是对于高转速,由于界面摩擦剪切应力没有上限,采用经典的Coulomb接触模型无法模拟,需采用修正的Coulomb接触模型.搅拌头转速的增加不会改变搅拌摩擦焊接技术固态连接的本质.当采用高转速时,焊接构件上、下表面的变形趋于均匀.有利于得到均匀的显微结构. 相似文献
6.
7.
采用基于固体力学的有限元方法建立了搅拌摩擦焊接过程的三维数值模型,研究了搅拌摩擦焊接技术在焊接非直线焊缝时材料的流动行为以及焊接过程中的力学特征。结果显示,搅拌焊接构件后退侧材料的流动较前进侧更为剧烈,且越靠近肩台部分材料的流动速度越大,搅拌头向原焊接构件前进侧移动将导致材料流动速度增加,搅拌头平移方向变化的瞬时会明显改变搅拌头周围材料流动速度的分布规律。搅拌探针-焊接构件接触面上的接触压力分布是比较均匀的。 相似文献
8.
摩擦搅拌焊接过程温度场的测量分析 总被引:1,自引:0,他引:1
温度场的分布不仅影响到摩擦搅拌焊缝区的材料流动,而且直接影响到焊缝各个区域微观组织结构,从而决定了焊接件的性能。结合试验研究了焊接工艺参数,主要是焊接速度和搅拌头旋转速度对2024铝合金焊接过程温度场的影响规律,得到了温度场在时间和空间上的分布规律,以及温度随焊接速度和搅拌头转速的变化规律,并研究了转速/焊速比对温度场的影响。 相似文献
9.
搅拌摩擦焊接过程中搅拌头转速对材料流动的影响 总被引:6,自引:0,他引:6
使用有限元方法模拟了不同搅拌头转速下,搅拌摩擦焊接过程中Al6061~T6材料的三维流动,以及材料流动与搅拌头转速的关系,结果表明,在搅拌摩擦焊接过程中,后退侧的材料流动较前进侧更为剧烈,并且随着搅拌头转速的增加,材料流动也会得到不同程度增强,搅拌头前方的材料在搅拌头的推动作用下向上涌起,被旋推到搅拌头后方并向下运动,该过程的周而复始是促使搅拌摩擦焊接顺利完成的主要原因,等效塑性应变等值线的形状与材料热影响区,热力影响区以及搅拌区的边界形状具有较好的对应关系,随着搅拌头转速的增加,等效塑性应变随之增加。 相似文献
10.
基于欧拉模型的搅拌摩擦焊接界面行为及产热数值 总被引:1,自引:0,他引:1
通过建立欧拉模型,研究搅拌摩擦焊接过程中搅拌头-焊接工件接触面材料的流动规律以及热输入,确定了搅拌摩擦焊接中接触面滑移系数与搅拌头转速之间的关系式,发现接触面滑移系数随搅拌头转速的增加而降低。通过与已知试验数据的对比,验证了所建立公式和模型的正确性;进一步发现,塑性变形产热对搅拌摩擦焊接过程中的热贡献超过35%。 相似文献
11.
12.
Friction stir welding of AZ31 magnesium alloys processed by equal channel angular pressing 总被引:1,自引:0,他引:1
Equal channel angular pressing (ECAP) is an effective thermo-mechanical process to make ultrafine grains.An investigation was carried out on the friction stir welding (FSW) of ECAPed AZ31 magnesium alloys with a thickness of 15 mm.For different process parameters,the optimum FSW conditions of ECAPed AZ31 magnesium alloys were examined.The basic characterization of weld formation and the mechanical properties of the joints were discussed.The results show that the effect of welding parameters on welding quality was evident and welding quality was sensitive to welding speed.Sound joints could be obtained when the welding speed was 37.5 mm/min and the rotation speed of the stir tool was 750 r/min.The maximum tensile strength (270 MPa) of FSW was 91% that of the base materials.The value of microhardness varied between advancing side and retreating side because of the speed field near the pin of the stir tool,which weakened the deformed stress field.The value of microhardness of the welding zone was lower than that of the base materials.The maximum value was located near the heat-affected zone (HAZ).Remarkable ductile character was observed from the fracture morphologies of welded joints. 相似文献
13.
Macrostructures and mechanical properties of ultrasonic-assisted friction stir welding joint of 2024-T3 aluminium alloy 下载免费PDF全文
In friction stir welding of aluminum alloys, tunnel defect may occur due to insufficient plastic material flow caused by lower heat input in the weld region. The inadequacy in heat input is due to improper selection of friction stir welding tool and process parameters. Ultimately, such defects degrade the properties of weld and may pose serious concerns towards the integrity and safety of the weld component. In order to improve the properties of weld joints, an ultrasonic-assisted friction stir welding device has been configured where ultrasonic energy is transferred from an ultrasonic unit directly into one of the workpieces near the tool. Using this configuration, ultrasonic-assisted friction stir welding was conducted on 6 mm thick 2024-T3 aluminum alloy sheets. The macrostructure and mechanical properties of these welds were compared with the welds of this alloy prepared by conventional friction stir welding using identical process parameters. The results show that the welding speed can be increased while satisfactory weld quality is still ensured. The ultrasonic energy transferred in this configuration could enlarge the volume of weld nugget zone. Also, the influence of ultrasonic energy on the suppression or elimination of the tunnel defect is quite apparent. However, any beneficial effects of ultrasonic vibration on the tensile strength and the elongation of the joint were less obvious in this configuration. 相似文献
14.
The effects of welding parameters on material consolidation are examined during friction stir butt welding of 2 mm Al 5083 alloy aluminium sheet with a surface cladding of Al 3025 alloy, which was co-cast from the melt. The influence of welding parameters on joint consolidation is investigated when tool revolutions per minute, travel speed and penetration depth were varied. It was found that modifying the pin of the welding tool to have a two-flat profile improves material consolidation and avoids defect formation during welding, and optimum welding parameters involve a combination of high tool rotation speed and travel speed. Optical and electron microscopy revealed that the integrity of the surface cladding layer could be maintained during friction stir welding while avoiding defect formation within the stir zone of the weld. The tensile strength of the joint was ~58% of the base material due to softening within the stir zone. 相似文献
15.
16.
Ti-6Al-4V钛合金搅拌摩擦焊缝的织构(英文) 总被引:1,自引:0,他引:1
采用W-Re合金搅拌头对α+β双相Ti-6Al-4V钛合金进行搅拌摩擦焊并在合适的工艺参数下获得无缺陷焊缝,利用取向成像显微镜对Ti-6Al-4V钛合金搅拌摩擦焊缝的织构进行研究。Ti-6Al-4V钛合金母材为轧制退火态,组织由变形的初生α相和转变β组织构成,具有典型的轧制织构。焊核区组织与母材明显不同,由大量的等轴动态再结晶晶粒组成,并在搅拌摩擦焊过程中形成{φ1=30°,φ=62°,φ2=30°}取向的织构。 相似文献
17.
Dissimilar friction stir welding between 5052 Al alloy and AZ31 Mg alloy with the plate thickness of 6 mm was investigated. Sound weld was obtained at rotation speed of 600 r/min and welding speed of 40 mm/min. Compared with the base materials, the microstructure of the stir zone is greatly refined. Complex flow pattern characterized by intercalation lamellae is formed in the stir zone. Microhardness measurement of the dissimilar welds presents an uneven distribution due to the complicated microstructure of the weld, and the maximum value of microhardness in the stir zone is twice higher than that of the base materials. The tensile fracture position locates at the advancing side (aluminum side), where the hardness distribution of weld shows a sharp decrease from the stir zone to 5052 base material. 相似文献