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采用化学成分分析、裂纹宏观分析、硬度测试及金相检验等方法,对传感器罩模具的横向开裂进行了检验和分析。结果表明:导致该传感器罩模具横向开裂的主要原因是模具材料成分尤其是碳化物偏析。 相似文献
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H13钢挤压模淬火后出现开裂.对开裂模具进行了化学成分分析和金相检验,以揭示模具开裂的原因.结果表明,该模具的含铬量超标,且存在化学成分偏析和显微孔隙等缺陷,从而导致模具淬火开裂. 相似文献
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冷作模具D2钢经过热处理、焊接、磨削后,在静置时产生脆性开裂.采用金相检验、化学成分分析和硬度测试等方法对开裂模具进行研究.结果表明,模具的开裂主要是由于模具后续焊接不良以及未消除焊接应力引起,提出了相应的改进措施. 相似文献
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采用外观检查、硬度试验、化学分析和金相检验等方法对计算机键盘塑料用模具型腔表面开裂原因进行了分析。结果表明,该模具的开裂属于典型的应力腐蚀开裂,是由于模具设计不合理、热处理工艺不当和模具背面电火花加工后未进行去应力处理等因素所致。 相似文献
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利用扫描电镜、金相显微镜、电感耦合等离子发射光谱仪等手段,对压铸ADC12铝合金云台基座开裂失效进行组织及成分分析,并借助弹塑性有限元法分析了云台基座在使用过程中采取急停等操作后的应力分布情况。结果表明,ADC12铝合金在铸造过程中产生大量的缩孔、偏析等缺陷,特别是在弯角部位,存在偏析瘤。这些缺陷,导致合金的力学性能严重下降。此外,在基座底部前后端与高台的交界处存在应力集中。因此,导致压铸ADC12铝合金云台基座的开裂失效。 相似文献
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Shunqi Wang Wei Liang Yu Wang Liping Bian Kehua Chen 《Journal of Materials Processing Technology》2009,209(7):3182-3186
Tensile stress occurs in the vicinity of upper surface of the specimen in the severe plastic deformation zone, which increases the cracking and fracture tendency of the specimen and impedes the further ECAP processing. In this paper, the conventional ECAP die (Ψ = 16° and Φ = 90°) was modified to eliminate the tensile stress and enhance the compressive stress in the severe plastic deformation zone, therefore reducing the cracking and fracture tendency of the specimen. Finite element analysis demonstrated that the stress state changes from tensile to strongly compressive when using the modified die. A modified die was made and employed to extrude the commercially pure aluminum to verify its effectiveness experimentally. The billet was successfully extruded for 20 passes without obvious surface defects with the modified die, compared to 13–14 passes at most for the conventional die. Consequently, much more fine and uniform microstructure was obtained with the average grain size of 200–300 nm, while the average grain size is ~500 nm in the case of using the conventional die. 相似文献
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用扫描电镜(SEM)及能谱(EDS)分析等手段,分析加氢高压换热器Ω环开裂原因。结果表明,Ω环的开裂属于H2S应力腐蚀开裂,高的工作应力和壳程少量硫化氢的存在共同促使其开裂。 相似文献
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Bogdan Pawlowski 《工业材料与腐蚀》1986,37(8):448-451
The susceptibility to stress corrosion cracking of Cr-Mn-Si-Ni steel in 3.5% aqueous sodium chloride solution was determined. The KIscc values for the specimens having two different microstructures and comparable mechanical properties were obtained. It was found that the susceptibility to stress corrosion cracking of specimens with lower bainite + martensite microstructure was only about one-half of the specimens with martensitic microstructure. This is probably due to the lower solubility of the hydrogen in the bainite. The microfractographic analysis of specimens tested for KIc and KIscc values have been done. 相似文献
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为解决一种2Cr13钢异形模锻件淬火回火后批次性表面开裂的问题,从复查工艺过程入手,通过计算机模拟工件淬火过程中表面应力状态变化,观察开裂工件显微组织及裂纹形貌,分析工件淬火开裂原因,并通过热处理试验验证了淬火制度对工件表层组织以及力学性能的影响。结果表明,2Cr13钢异形模锻件淬火后出现表面裂纹与锻件形状、淬火加热方式以及淬火温度有关,可通过增加锻件过渡区余量、采用到温入炉以及较低的淬火加热温度的方式降低淬火开裂风险。采用1000 ℃淬火,到温入炉作为产品优化后的热处理制度。 相似文献
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Temperature change and stress distribution analysis of die surface in Al-alloy die casting process and experimental study on die heat check 总被引:1,自引:0,他引:1
The temperature change of the die surface in practical aluminum alloy die casting process was analyzed, and a 2D model was formulated on the basis of a deep concave round cavity without sliding core to analyze the stress distributions along the die surface in detail. Equipment was designed to test the thermal state of the die steel in different thermal loading conditions. The results of stress analysis showed that, the value of thermal stress (maximum 1.5 GPa) caused in the die filling and die spraying stages was larger than the mechanical stress (maximum 85 MPa) caused in the die locking stage. The results of the thermal check experiment showed that there were three stages of die dissolving, and that the stress distribution shown by the samples' cracking routine was close to the die surface stress analysis. 相似文献
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分析了Cr12MoV模具钢淬火开裂原因,借助于扫描电镜和光镜,观察断口表面形貌和金相组织,根据断口特征和金相组织分析,该模具钢淬火开裂的主要原因是晶粒粗大、碳化物呈不均匀状态分布。 相似文献