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M7120A传动螺杆开裂失效分析 总被引:1,自引:1,他引:0
通过对M7120A传动螺杆开裂断口的宏观观察、金相分析、电子扫描分析以及淬火丁艺分析.找出螺杆开裂失效的原因,并提出了改进措施和建议,取得了较好的效果。 相似文献
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通过开裂工件的外观分析及跟踪生产过程,发现造成40Cr螺杆调质开裂的原因是多方面的,既有设备(主要是热电偶)的原因,也有技术人员设计金加工工艺不当的原因,更重要的是淬火介质浓度较低、加热温度过高、工件冷的过透的原因。 相似文献
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对渗氮K340钢塑料挤出螺杆和渗氮K340钢刀盘的开裂原因进行了分析.结果表明,挤出螺杆发生断裂是由校直工艺不当和渗氮层过厚双重因素引起的;刀盘边缘崩刃则是由渗氮层过厚引起. 相似文献
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螺杆心部空洞形成原因分析 总被引:1,自引:0,他引:1
经对带有空洞的B7M20螺杆样品的宏观和微观检查和分析,结果表明螺杆心部的空洞为氢致开裂(HIC)所致。空洞是在滚牙至最终热处理之间形成的。螺杆心部具有高的残余应力、较严重的碳偏析及拉拔后的酸洗为螺杆心部出现HIC空洞提供了条件。 相似文献
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SCM440钢冲床球头螺杆使用了约1年就发生断裂。采用断口检验、金相分析、化学成分分析和力学性能测试等方法分析了球头螺杆断裂的原因。结果表明:球铁螺杆的显微组织为网状铁素体,晶粒粗大,并存在夹杂物、孔洞及锻造裂纹等缺陷,螺杆热处理过程中裂纹从这些缺陷处产生,并在使用中在应力的作用下扩展,最终导致螺杆断裂。 相似文献
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针对中大直径铝合金螺柱焊接过程中出现气孔、未熔合、热裂纹等缺陷及焊接接头性能不良问题,以直径16 mm螺柱为研究对象进行了铝合金螺柱焊方法和工艺的探索性研究.提出了TIG-拉弧复合热源焊接技术,在焊前对铝螺柱采取预浸镀一层锌镍的处理方法,整个施焊过程处于惰性气体保护的状态下.力学性能检测得到接头抗剪强度能够达到128 MPa,其强度系数为70%以上.最佳焊接工艺参数为:预热150℃、焊接电流650 A、焊接时间1 000 ms.结果表明,铝板焊前TIG预处理、螺柱预浸镀锌镍等都能够有效的提高螺柱焊接接头力学性能,并且改善焊缝组织. 相似文献
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对固定支架的GH4169 M60断裂螺柱进行宏观和微观分析。目视检查断裂表面,发现裂纹的特征是脆性断裂,并且断裂最终发生在螺柱螺纹和螺母的接合处。渗透测试发现,螺柱内有5个平行于螺纹的连续裂纹,通过扫描电镜发现,断裂部位螺纹之间的裂纹呈现出不规则的尖锐边缘,且断裂表面呈现出典型的准劈裂断裂特征。EDS验证了断裂中碳化物相的存在,并分析了碳化物对脆性断裂的影响。分析表明,螺纹易于引起应力集中,从而提高了螺柱对缺陷的敏感性,导致脆性断裂。与无螺纹试样的断裂表面微观形貌相比较,发现断裂与材质本身无关,破碎的碳化物是GH4169韧-脆混合型断口典型特征。 相似文献
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《Acta Materialia》2000,48(8):1865-1882
The plane problem of a brittle piezoceramic with an arbitrarily oriented branched crack is theoretically investigated in this study. Lekhnitskii’s complex potentials and a distributed dislocation model are employed to formulate the problem. The crack closure is taken into consideration. The branched crack problem is reduced to solving three singular integral equations. The accuracy of the present scheme is confirmed by comparison with the existing results in the literature. The results obtained in this study present critical information about the electroelastic fields and fracture parameters associated with a branched crack in piezoceramics. Numerical results show that applied electric loading has a significant effect on branched cracks. The criterion of a modified hoop stress intensity factor, which accounts for fracture toughness anisotropy, is applied to predict potential branching directions. Numerical examples indicate that a crack may branch off from a straight path even under symmetric loading and geometry. The present scheme complemented with an experimentally validated fracture criterion can be used to simulate crack branching in piezoelectrics. 相似文献
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Buchibabu Vicharapu Luis Fernando Kanan Amitava De 《Science & Technology of Welding & Joining》2017,22(7):555-561
Friction hydro pillar processing (FHPP) is a novel technique to fill in crack-holes in thick-walled metal structures by an external stud and forming a solid-state bond between the stud and the metal substrate. During the process, the stud is rotated against the crack-wall to facilitate friction heating and flow of plasticized material for proper filling of the crack-hole. We present here a coupled experimental and numerical study on FHPP of ASTM A36 steel to understand the effect of processing conditions on the joint structure and properties. An axi-symmetric heat transfer analysis is carried out to compute the temperature field. The computed thermal cycles are used to estimate the hardness distribution across the joint. The estimated thermal cycles and hardness distribution are tested with the corresponding experimentally measured results. 相似文献
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0IntroductionArc stud welding is gradually becoming an increasingimportant joining process fromthe firstpractical applicationdeveloped originally for the shipbuilding industry as a re-placement of the time consuming drilling and boltingprocess in1939[1].T… 相似文献
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Ultrasonic testing using a normally incident longitudinal wave is used for sizing a closed crack. The crack exists vertically on the back-wall of the inspected plate. In order to evaluate the closed crack, the relationship between the first back-wall echo height and the crack depth for an open crack as the basis for evaluating the closed crack is determined experimentally and is introduced to the analysis of echo height for the closed crack. The unknown parameters in the evaluation of the closed crack, such as crack depth and the stress closing the crack, are determined by comparing the first back-wall echo height obtained through both analysis and experiment on the closed crack. 相似文献
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采用Abaqus有限元计算软件,对摩擦螺柱焊的焊接过程进行了仿真研究.通过在Abaqus/stand算法的基础上利用Python脚本编程实现了参数化建模、网格自动重划分以及结果映射、散热边界自动选取等功能,有效解决了焊接过程中由于材料大规模非线性塑性变形导致的计算收敛困难问题.仿真计算获得的螺柱塑性变形情况与实际焊接结果基本一致,有效证明了该有限元模型的合理性.另外,通过对焊接温度场及应力场结果的分析,较好的解释了干式环境和有水环境下采用相同焊接工艺参数的焊接接头质量存在差异的现象,这对摩擦螺柱焊技术的水下应用及其工艺参数研究具有重要的指导意义. 相似文献