LF2铝合金搅拌摩擦焊接头的疲劳特性

对LF2铝合金搅拌摩擦焊接头的疲劳特性进行了研究，建立了焊接头的S-N曲线。疲劳试验结果表明，搅拌摩擦焊接头表现出良好的疲劳性能，疲劳寿命N=10^6次的疲劳强度值约为59～65MPa。搅拌摩擦焊接头具有细小的等轴晶粒和狭窄的热影响区，阻碍了滑移带的形成和裂纹的扩展，从而提高了接头的疲劳性能。疲劳断口分析显示，随着驻留滑移带的扩展逐渐萌生裂纹，在交变应力作用下最终导致失效。     

环境条件下Ni3Al类型金属间化合物的疲劳行为

综述近年来Ni_3Al类型金属间化合物疲劳行为的研究进展，着重讨论了温度和介质对材料疲劳性能的影响。氢和水蒸汽的存在促进了裂纹的扩展；试验温度的升高使Ni_3Al类型合金的疲劳裂纹扩展速率增大。     

高压地下储气井专用套管疲劳性能评价

根据高压地下储气井服役情况，设计了用于实施高压地下储气井专用套管行业标准SH／T6535-2002评定其疲劳性能的试验方法，对天津钢管有限责任公司生产的专用套管疲劳性能进行了评价，并对实施该标准的方法进行了讨论。     

电刷镀Fe-Re对20CrMnTi钢疲劳性能的影响

通过20CrMnTi钢经电刷镀Fe-Re、电刷镀Fe和离子硫碳氮共渗处理的对比试验,分析了其疲劳前后的硬度变化、疲劳断口形貌、疲劳源的位置和过渡层的强度等问题.结果表明,20CrMnTi钢经Fe-Re电刷镀可显著提高弯曲疲劳强度,比电刷镀Fe和离子硫碳氮共渗分别提高了9.9%和21.9%,增加了刷镀层的厚度,提高了过渡层强度,并使疲劳源位置向心部推移,从而有效地增强了20CrMnTi钢的疲劳强度和超负荷持久性.     

铸钢车轮材料在600℃-200℃循环温度幅下热疲劳断裂行为探讨

研究了铸钢车轮材料在循环温度幅600-20℃下的热疲劳断裂行为。研究发现，试样表面氧化较为严重，表面开裂加速了次表层裂纹的形核扩展。断口裂纹以沿晶为主，并有少量穿晶裂纹，表明高温蠕变对热疲劳试验过程有着相当的作用。同时，断口的破坏和表面的破坏起到了相互促进的作用。     

未焊透焊缝疲劳强度分析及工程应用

本文针对工程中焊接结构大量采用单面焊对接焊缝这一事实,对含有未焊透缺陷的单面焊对接焊缝试件进行了疲劳试验,得到了疲劳强度曲线。由于单面焊对接焊缝中的未焊透缺陷位于试件根部表面,在缺陷率相同的条件下,其疲劳强度损失比双面焊未焊透焊缝更严重。试件母材为低碳钢钢板(σ_b≥450MPa)。本试验结果应用于钢瓶焊缝的缺陷容限分析,为制订我国民用在役液化石油气钢瓶判废标准提供了实验依据。     

PRB250/31.5乳化液泵曲轴结构的有限元--优化分析

本文以乳化液泵曲轴为研究对象，应用ANSYS5．7有限元软件，对整个曲轴进行有限元分析，旨在探索一种确定多拐曲轴的危险相位和危险点的方法，继而进行考虑圆角的疲劳强度分析，从而达到优化曲轴结构，提高泵的设计水平之目的。     

碳化钨钢结硬质合金渗硼层热疲劳特性的研究

本文对GJW50碳化钨钢结硬质含金进行了粉末渗硼处理，在自约束型热疲劳试验机上进行了25－680℃的效疲劳试验．用光学显微镜和扫描电镜观察了在突变热应力的作用下，热疲劳裂纹在渗硼层萌生、扩展的全过程．试验结果为表面硬化处理在碳化钨钢结硬质含金热作模具上的应用提供了理论依据．     

Fatigue crack growth behavior of laser-processed 304 stainless steel in air and gaseous hydrogen

Fatigue crack growth test was performed to evaluate fatigue behavior of 304 stainless steel specimens with or without laser processing (welding and surface treatment) in air and gaseous hydrogen. As the crack propagation normal to the laser welding or scan direction, the laser-processed specimens exhibited a higher resistance to crack growth in the low stress intensity factor range (ΔK) than the as-received steel plates regardless of testing environments. However, the marked retardation of crack growth behavior vanished for welded specimens subjected to a 850 °C/h stress relief treatment or with a shorter distance from notch tip to the weld centerline in the test.Fatigue-fractured appearance of the steel plate tested in air was composed of mainly transgranular fatigue fracture and some flat facets, along with a small amount of intergranular fracture. While quasi-cleavage fracture and few twin boundary separations were observed for the same specimen in hydrogen. On the other hand, the lower crack growth rate of laser-processed specimens in both air and hydrogen was accompanied with rubbed areas on the fracture surfaces. It was found that the extent of quasi-cleavage fracture was related to the formation of strain-induced martensite, which would contribute to an increased fatigue crack growth rate of all specimens in gaseous hydrogen.     

The effect of oxide coatings on fatigue properties of 7475-T6 aluminium alloy

The effect of hard anodic oxide and plasma electrolytic oxide coatings on the fatigue strength of 7475-T6 aluminium alloy has been investigated. The coated aluminium alloy was tested using constant load uniaxial tensile fatigue machine. Hard anodising led to an appreciable reduction in the fatigue strength of 7475-T6 alloy of about 75% for a 60 μm thick coating. Further, plasma electrolytic oxidation resulted in reduction of the fatigue strength of about 58% for a 65 μm thick oxide coating. The decrease in fatigue strength of the hard anodic oxide coatings was associated with the stress concentration at the microcracks in the coating. The better fatigue performance of the PEO coatings was attributed to the development of the compressive residual internal stress within the coatings. The reduction in the fatigue strength of the PEO coatings as compared to the uncoated material was associated with the development of the tensile residual internal stress within the substrate. This may cause an early crack initiation in the substrate adjacent to the coating.