Corrosion fatigue short crack growth behaviour in a high strength steel

The influence of an aggressive environment (0.6 M, aerated NaCl solution) on short fatigue crack initiation and growth behaviour has been studied. The study involved three major test series, namely: air fatigue, corrosion fatigue, and intermittent air fatigue/corrosion fatigue. The above tests carried out under fully reversed torsional loading conditions at a frequency of 5 Hz, showed that it was the non-metallic inclusions which took part in crack initiation resulting from debonding at metal matrix/inclusion interface and pitting of inclusions in both air and corrosove environments, respectively. Short fatigue crack growth results in these two environments obtained by using plastic replication technique, indicated a large effect of microstructure i.e. prior austenite grain boundaries. The stage/stages at which the environmental contribution was dominant has been discussed by considering the results achieved from intermittent tests. However, the mechanisms involved in corrosion fatigue short crack growth have also been described in the light of results obtained from futher investigations carried out by conducting corrosion fatigue tests under applied cathodic potential conditions and tests on hydrogen pre-charged specimens under air fatigue and uniaxial tension conditions.     

低合金高强度钢的微观组织和疲劳裂纹扩展行为

用透射电镜观察了３０ＣｒＭｎＳｉＮｉ２Ａ钢等温的微观组织，疲劳裂纹扩展行为、裂纹尖端塑性区和位错结构，结果表明，等温状态组织由马氏体和贝氏体组成。在一个奥氏体晶粒内一般存在四个板条领域、裂纹尖端的塑性区内存在主位错带，疲劳断裂的基本组织单元为板条晶或板条束。裂纹遇到板条束界时方向发生较大偏斜。     

Failure analysis of a wire rope

Wire ropes, pulleys, counterweights, and connecting systems are used for auto tensioning of contact wires of electric railways. A wire rope in one such auto tensioning system suffered premature failure. Failure investigation revealed fatigue cracks initiating at nonmetallic inclusions near the surface of individual wire strands in the rope. The inclusions were identified as Al-Ca-Ti silicates in a large number of stringers, and some oxide and nitride inclusions were also found. The wire used in the rope did not conform to the composition specified for AISI 316 grade steel, nor did it satisfy the minimum tensile strength requirements. Failure of the wire rope was found to be due to fatigue; however, the ultimate fracture of the rope was the result of overload that occurred after fatigue failure had reduced the number of wire strands supporting the load.     

磨损自补偿添加剂在成品油中的摩擦学效应

利用四球试验机考察了二聚酸－3－氯－2－羟基丙单酯（DAE）在4种成品油中的摩擦学性能。试验结果表明，DAE添加剂在L－HM68液压油和L－DAB100空压机油中具有良好的适应性，使其承载能力增强，摩擦系数降低及耐磨性增强；DAE在L－CKE涡轮蜗杆油中使耐磨性增强；DAE在L－CKC150齿轮油中虽使承载能力提高，减磨性增强，但有使耐磨性减小的趋势，说明DAE在不同的油中有不同的性能。     

烷基化换热器的腐蚀失效分析和防护措施

通过对烷基化车间换热器腐蚀形貌、特征、产物、腐蚀介质、积垢、材料以及换热器流体特性的研究和分析,认为烷基化换热器的腐蚀失效主要由空泡腐蚀和湍流腐蚀引起,并提出了4项防腐蚀措施.经现场应用证明:改变设计或安排辅助管可以有效地减缓冷却管与管板结合部位的严重腐蚀.     

两种不同界面结合强度碳/铝复合材料的内耗特性

本文研究了两种不同界面结合强度的碳/铝复合材料经不同次数加载热循环处理后的内耗值及内耗机制。弱界面结合的C/L2复合材料的内耗值变化主要由界面脱粘引起,而强界面结合的C/LD2复合材料的内耗值变化主要由位错运动所致。     

Tribological issues in reducing piston ring friction losses

In this paper improvement in fuel economy by reducing piston ring friction is studied and reduction of piston ring tension and the use of two-ring packages are found to be effective. However, these can be accompanied by adverse effects such as excessive wear and increasing oil consumption, and measures to overcome these problems are studied in detail.     

含硫氰基团化合物的摩擦学性能及其摩擦化学机理研究

以三烷基磷酸酯络合硫氰酸钙为模型化合物研究了含硫氰基团的络合物的摩擦学行为，发现它有高的承载能力，良好的抗磨减摩性。用俄歇能谱（ＡＥＳ）、Ｘ－射线衍射（ＸＲＤ）、扫描电镜（ＳＥＭ）及Ｘ－射线能谱（ＥＤＸ）研究了摩擦表面元素组成及其可能物相。探讨了摩擦化学机理，认为化合物中的硫氰基团对摩擦学性能起主要作用，并在摩擦过程中发生类似于化学热处理中的硫氰共渗。     

几种高强度钢腐蚀疲劳裂纹扩展行为的研究

本文研究了ＧＣ－４，３０ＣｒＭｎＳｉＮｉ２Ａ和３００Ｍ超高强钢的腐蚀疲劳裂纹扩展行为。考虑了环境，热处理制度，应力比和频率对裂纹扩展的影响。研究结果表明：腐蚀环境和热处理制度对疲劳裂纹扩展有显著影响。在侵蚀性环境中随频率降低，裂纹扩展大幅度上升，随应力比提高，环境影响加剧。利用扫描电镜对试样断口形貌进行了分析，并讨论了高强钢的腐蚀疲劳机理。     

结构陶瓷的高温疲劳强度衰减理论

提出了陶瓷材料疲劳强度衰减理论并由此导出了各种疲劳关系式。建立了疲劳基本方程ｄσ＿ｒ／ｄ＿ｉ＝一Ａσ（ｔ）￣ｎｔ￣（－ｍ），得出了疲劳寿命公式Ｔ＝Ｍ（σ＿０－σ）／Ａσ￣ｎ（静疲劳时Ｍ＝１，连续增载疲劳时Ｍ＝ｎ＋１，循环疲劳时Ｍ＝（ｎ＋１）／（１＋Ｒ＋Ｒ￣２＋……＋Ｒ￣ｎ），逐级加载时，并导出不同疲劳方式下疲劳寿命间的关系。同时，用多种Ｓｉ＿３Ｎ＿４材料在高温中作了论证试验，结果与理论一致。