Study on ASTM E399 and ASTM E1921 standards

Costs of ASTM E399 and ASTM E1921 tests, which were developed to determine the fracture toughness (K_Ic) and the ductile–brittle transition temperature of ferritic steels, respectively, are considered high and the procedures are also very complicated. In this study, a method, which is more cost‐effective and easier to carry out, is proposed.     

Failure analysis of three reconditioned rail car couplers

Three reconditioned rail car couplers, arbitrarily identified as couplers, failed during service due to cracking of the front face. The three couplers were reportedly upgraded by quenching and tempering to enhance strength and toughness. The objective of this investigation was to determine the mode of crack propagation and the root cause of the observed failures. Verl E. (Bud) Kahle, P.E., was a professional failure analyst for more than forty years. After receiving his Bachelor of Science degree in physical metallurgy from Washington State University 1957, Bud was employed by the General Electric Company at a facility in Hanford, Washington. He later was employed by the Aerojet General Corporation and eventually was head of the Southern Pacific Materials Science Laboratory in Sacramento. After retirement from Southern Pacific he owned and operated his own firm, Kahle Metallurgical Consulting Services, for fifteen years. He came to be known as “the man with the answers” to clients in a variety of industries. Bud was a Life Member of ASM International. Many of Bud’s clients remarked on the high quality of his failure analysis case histories and encouraged him to have them published. After Bud passed away in 1999, his wife, Suzanne, approached ASM International to see if the society would be interested in publishing any of his work. Mrs. Kahle was able to supply a large number of reports, which Bud had carefully archived over the years. Journal of Failure Analysis and Prevention Associate Editor Michael Stevenson read through the collected case histories, selected the ones to be included in this issue, and edited them for journal publication. ASM International wishes to thank Mrs. Kahle for providing these case histories for publication.     

糯扎渡心墙堆石坝心墙方案比较研究

糯扎渡工程在可行性研究阶段，比较了直心墙堆石坝和斜心墙堆石坝两种方案，分析表明，直心墙堆石坝在坝坡稳定性、坝体应力及抗震性方面均满足设计要求，且在地形地质条件、基础处理、抗震性能、施工方便性、工程造价等方面不同程度地优于斜心墙堆石坝，因此，设计最终选择直心墙堆石坝方案。     

Synergism of Toughening Mechanisms in Whisker-Reinforced Ceramic-Matrix Composites

The improved fracture resistance of whisker-reinforced ceramic-matrix composites involves more than one energy-absorbing mechanism. The possible mechanisms are reviewed and a micromechanical model evaluating the relative contributions to the overall toughness is presented. The mechanisms involve microcracking, load transfer, bridging, and crack deflection. The synergism of these mechanisms is examined using an energy release rate balance equation. The basic assumption of the proposed model is that the load transfer between the matrix and the whiskers is due to Coulomb friction. The model has been applied to an Al₂O₃/SiC whisker composite and shows reasonable agreement with reported experimental results. The role of the thermal residual stresses is also examined in light of the frictional load transfer assumption.     

Basic studies leading to the development of an ultrahigh strength,high fracture toughness low-alloy steel

Ultrahigh strength steels have been used increasingly in recent years for critical aircraft and aerospace structural applications. In such applications, though materials performance is of prime consideration, cost and availability makes the low-alloy steels an attractive option. This paper describes the development of an ultrahigh strength NiSiCrCoMo low-alloy steel, supported by significant findings obtained from the basic studies that were aimed at understanding how solute additions influence fracture resistance of iron, with and without the presence of carbon. The results of the basic studies, in combination with the work of Garrison (1986) on a NiSiCr steel, have profitably been employed in the development of a NiSiCrCoMo low-alloy steel possessing a strength-toughness combination quite comparable to the highly alloyed 250-grade maraging steel. Reproducibility of attractive strength and toughness properties has been established in tonnage scale melts. This steel, in the softened condition, has good formability and machinability. Weld parameters have also been established. The NiSiCrCoMo low-alloy steel thus meets the requirements of performance and cost rendering it an attractive option for advanced structural applications.     

SA299钢冷脆行为的研究

某锅炉厂生产的锅炉汽包,在冬季制造过程中发生破裂,汽包材料为 SA299钢,对断口的初步分析发现为脆性解理断口,据此认为是冷脆破坏。本文依据冷脆特征温度 Tc 的概念对 SA299钢的冷脆行为进行了细致的分析。     

An investigation of induced voltages to an underground gas pipeline from an overhead transmission line

This paper investigates induced voltage characteristics from an overhead transmission line by applying a method of modeling of induced voltages proposed by the authors. EMTP simulation results obtained by the modeling method agree with analytical results obtained from a well‐known formula. The induced voltages are significantly dependent on the configuration of the overhead line. A horizontal line induces the largest voltage in a gas pipeline, and the voltage induced by a vertical twin‐circuit line is about 20% smaller than that induced by a vertical single‐circuit line. The method is applied to a real pipeline system and the simulation results show reasonable agreement with field test results. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 43–51, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20465     

Photodegradation mechanism and stabilization of polyphenylene oxide and rigid‐rod polymers

Poly(2,4‐dimethyl‐1,4‐phenylene oxide) (PPO), poly(benzo[1,2‐d:5,4‐d′]bisoxazole‐2,6‐diyl‐1,4‐phenylene) (PBO) and poly(benzo[1,2‐d:4,5‐d′]bisthiazole‐2,6‐diyl‐1,4‐phenylene) (PBZT), which are polymers with extended conjugated structures, undergo a self‐sensitized photo‐induced electron‐transfer reaction. A second component is not required. This article presents many similar observations on these polymers when they are exposed to light and evidence to support the proposed photo‐induced electron‐transfer mechanism. Methods to stabilize these polymers against photo‐oxidation are also described. Workers investigating other conjugated polymeric systems may find the experimental methods, observations and polymer stabilization approaches discussed in this review useful. Copyright © 2005 Society of Chemical Industry     

精对苯二甲酸反应器桨叶断裂分析与修复

为了保证进口精对苯二甲酸装置氧化反应器中钛制搅拌器的正常工作，对钛制搅拌器桨叶在运行中断裂脱落的原因进行了分析，并叙述了桨叶修理的方法和要求。经修理后的桨叶投入生产使用，达到了预期的目标。     

Morphological aspects of rubber fracture and wear

Morphology of carbon black (CB)‐filled rubber was studied with AFM and SEM and the classification of filler agglomerates, based on their internal structure and filler–matrix interactions, has been proposed. It varies according to the activity of CB and the kind of rubber. It has been shown that fracture of rubber starts either inside filler agglomerates (de‐cohesion) or in a filler–matrix interphase (de‐adhesion) initiating wear of the material. Microscopic observations correlate well with TGA and EPR data of wear debris collected during friction of rubber. The increase of thermal stability of CB and the appearance of additional spin signals, respectively, for elongated samples or debris, are proposed to be associated with de‐cohesion or de‐adhesion of the agglomerates. New approach to the fracture of rubber called “fatal agglomerate concept” is presented. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008