共查询到20条相似文献,搜索用时 672 毫秒
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纵波探伤是检测中厚钢板内部质量的主要方式。探伤钢板按不同标准、不同级别进行检测判定。对于钢板内部存在的缺陷,有些是标准允许的,有些则是纵波探伤技术性问题而无法检测出来。目前对缺陷的定性、定量技术,还不能完全满足科研人员了解产品内部缺陷详细情况的要求。为此笔者阐述了探伤合格钢板存在缺陷的原因,及缺陷定性、定量的不确定性问题。 相似文献
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简述射线照相检测方法的缺陷检出灵敏度与对比度和可见度之间关系,射线照相灵敏度与产品透照技术等级、缺陷评定质量级别的关系和重要性。介绍检出缺陷尺寸几个关系式,说明影响检出缺陷灵敏度的主要因素及标准中的几个隐含参量。射线检测人员在实际工作中,在考虑影响因素的同时,可用公式计算结果预计所能达到的检测灵敏度。 相似文献
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1 问题的提出在生产实际中,46mm厚钢板沿切割线有不连续状或线状缺陷,而在切割前已沿切割线两侧各50mm处进行了超声波探伤,有微略而非连续的缺陷波显示,其结果肯定是Ⅰ级钢板,即是合格的.但用埋弧自动焊焊接完毕后,用超声波探伤时,却滑坡口平行线出现焊缝超标缺陷显示 相似文献
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通过微观形貌和成分分析研究了低碳铝镇静钢经氮氢罩式炉退火处理后冷轧钢板表面出现的丝斑缺陷。结果表明,无丝斑缺陷的钢板表面均匀光亮,钢板表层无异常的碳元素富集;有丝斑缺陷的钢板表面明显发黑、呈丝带状,缺陷部位呈岛状或线状,异常元素是石墨碳,在钢板表层一定深度范围内碳元素含量明显高于钢板基体。 相似文献
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以单层0.3 mm厚的薄铜板叠6层进行冲裁,研究冲裁间隙对多层薄铜板成形的影响。对多层薄铜板在冲裁成形中的受力与应力状态进行分析,利用ABAQUS软件对多层薄铜板在不同冲裁间隙下的冲裁质量进行有限元仿真。研究表明:冲裁初期最大等效应力出现在凸凹模刃口处,导致最上层与最下层薄铜板先行断裂,中间层薄铜板受相邻层挤压,最大等效应力出现在软质凸凹模刃口处,最后出现在中间层薄铜板缩紧截面内;随着冲裁间隙的增加,各层薄铜板拉伸变形明显,导致冲孔直径增大、毛刺高度增加。前3层薄铜板的冲孔直径变化较为稳定,与凸模直径接近;后3层薄铜板的冲孔直径变化幅度较大,与各自凹模直径接近。最后,通过试验验证,冲裁精度符合国标要求,在实际生产过程中选择合理的、尽可能小的冲裁间隙能提高冲裁件的冲裁质量。 相似文献
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Possibilities of air-coupled ultrasonic testing and imaging are examined by means of a measurement system designed for both through-transmission and reflection technique. For that purpose, B- and C-scans have been performed with respect to a wide variety of materials of different acoustic impedance. The observations reported in the paper deal with coating on textile, flaws in an aluminum plate, spot welds on metallic plates, tiny air inclusions in thin castings and ultrasonic reflection on an epoxy plate with a copper layer. The measurements have been performed in either continuous or pulse mode. In the former case, frequency swept sinusoidal signals are applied, in the latter modulated chirps. All results have been obtained at sound frequencies between 0.75 and 2 MHz, produced by air-coupled piezo-based transducers with matching layer. 相似文献
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分析了控制焊缝移动的拼焊板薄厚两侧所需的压边力关系式,并据此提出了变压边力控制方案。通过数值模拟对比分析了不同方案的冲压结果,验证了:减少厚侧压边力可有效的降低焊缝向薄侧的移动量,从而降低薄侧材料应力集中,改善应力状态,大大提高了拼焊板的成形性能。 相似文献
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对T12A,GCr18Mo,CrMn及25Cr2Ni4WA(渗碳)钢中形成的蝶状马氏体的金相观察表明,蝶状马氏体的中脊面是薄板状马氏体.蝶状马氏体的形成是一种复生过程,初始阶段形成交叉的或铰接的薄板状马氏体,然后以它为中脊面,侧向长大成有蝶尾蝶状马氏体或无蝶尾蝶状马氏体.蝶状马氏体的生成不是一步完成的,在时间上可以分为几个独立的阶段. 相似文献
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Liquid forging is a pressurized solidification process, wherein finished components can be produced in a single process from molten metal to solid, utilizing re-useable die tools. In conventional die casting (gravity and pressure), components with a minimum wall thickness of about 0.6 mm can be fabricated. However, parts with section thickness as thin as 0.2 mm can be liquid forged using near eutectic Al–Si or Al–Si–Cu alloys. Water based lubricant containing micrographite is effective in releasing the component during ejection. In addition, it aids in shaping the component to required dimensional accuracy. These liquid forged parts are pore free. Thermal analysis of liquid forged 0.8 mm plate revealed rapid freezing at the rate of about 700 °C/s. During the process, die and punch were maintained at 200–250 °C. X-ray residual stress analysis on the surface of the liquid forged plate showed high intensity values for 0.1 mm plate. Distribution of eutectic silicon at inter dendritic region is extremely fine to nanoscale level. 相似文献
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