湖北沼山珍珠岩及应用研究

本文对湖北沼山珍珠岩进行了矿物、化学成分和膨化工艺研究,同时进行以水泥和水玻璃为粘结剂的膨胀珍珠岩制品的研制。其中以425、525号水泥为粘结剂的中试产品达到国家GB10303—89优等品的标准。本文所论及的方法和制品为该地区珍珠岩矿床评价提供了实验依据,也为沼山珍珠岩制品厂提高产品质量找到了有效途径。     

A Transmission-Electron-Microscopy Study of the Substructure of High-Purity Pearlite

Using transmission electron microscopy, many of the substructural faults of pearlite colonies were identified and characterized. It was found that a ferrite subgrain boundary can affect the growth of a cementite lamella depending upon the orientation of the boundary with respect to the growth direction of the lamella. Other substructural features found were: dislocations at the cementite-ferrite interface, discontinuities in cementite lamellae containing a high density of dislocations, and growth steps in cementite lamellae. The observed phenomena are discussed in terms of the origin of dislocations and substructural faults in a growing pearlite colony.     

T8Mn钢珠光体连续冷却转变动力学

用定量金相法Ｆｏｒｍａｓｔｏｒ－Ｄｉｇｉｔａｌ膨胀仪分别测得Ｔ８Ｍｎ钢以１℃／ｍｉｎ冷速下和不同冷速下的连续冷却动力学曲线。用线笥回归分析法得到动力学转变的数学模型。     

35T／H循环床锅炉埋管破裂分析

某３５Ｔ／Ｈ循环床锅炉埋管运行仅２个月，即发生管子破裂。采用光学显微镜、化学分析和力学性能测试方法对裂管进行了分析，结果表明，由于埋管局部区域超温，促使珠光体球化，最终导致力学性能下降而破裂。提出了预防措施。     

Tensile,Compression and Fracture Properties of Thick-Walled Ductile Cast Iron Components

The article presents the outcome of a comprehensive program of tensile, compression and fracture toughness experiments, addressing thick-walled ductile cast iron inserts used for the production of three nuclear waste canisters. The resulting data are required as input to the assessment of the failure probability of the canisters. Moreover, these data are useful for the improvement of the casting technique as such. Although the same material specification is always used, material properties are found to show significant variation. Considerable attention is paid to linking the scatter in tensile properties to fractographic and microstructural observations. The main finding is that low ductility tensile test results can be primarily connected to the presence of specific casting defects, from which oxide films have the most detrimental effect. Another important observation is that compression experiments do not result in low ductility failure. During fracture testing, stable ductile crack propagation is observed. Basic fracture analysis of a tensile test is performed in order to better understand the effect of defect size, stress-strain behavior and fracture toughness on the ductility measured through tensile testing. Two opposing specimen size effects are observed.     

Influence of 1 wt-% addition of Ni on structural and mechanical properties of ferritic ductile irons

Abstract

Two sets of ductile irons with and without Ni additions containing various low Si contents have been prepared in order to study the effect of Ni on structural and mechanical properties of thermal analysis cups and standard keel blocks. Because contradictory results appearing in literature, this work has been focused on the influence of this element on matrix structure and on impact properties at room temperature as well as at low temperatures. The structures of Ni free and Ni bearing alloys have been related to the features of cooling curves recorded on both casting types and to the tensile and impact properties of the materials.     

球墨铸铁件铁素体与珠光体形成的数值模拟

通过对球墨铸铁件共析转变的分析,改进了球铁件中铁素体与珠光体形成的数学模型。其中提出了合金影响因子,考虑了合金元素对铁素体生长的影响。对实际汽车制动臂球铁件进行模拟,并取样进行定量金相实验分析,对模拟结果进行验证。结果表明,改进的模型可以更准确地预测球铁中铁素体和珠光体的数量,能够准确地体现共析阶段过冷情况和共晶球墨数对珠光体数量的影响。     

锰和硅添加对重度冷轧及退火后珠光体钢力学性能的影响

研究了几种锰、硅含量的Fe-0.8C合金在重度冷轧及退火后珠光体的显微组织变化及拉伸性能。结果表明,锰、硅的添加可使90%冷轧及450-650℃退火后共析珠光体的抗拉强度与屈服点均大幅度提高,但它们对冷轧珠光体延性的影响却是可以忽略的;与锰相比,硅的添加对冷轧及退火后珠光体钢延性的提高更有效,尤其当钢的强度较高时;锰、硅复合添加对重度冷轧及退火珠光体钢力学性能的提高也同样非常有效;经重度冷轧及低温(450℃)短时间退火,含硅或锰钢的抗拉强度和屈服点与冷轧态试样相比几乎没有下降,但其延性却明显提高;以硅、锰合金化的共析珠光体钢经90%冷轧及在450℃退火30-120s后强度-延性平衡达到最佳。