提升连铸机结晶器水箱把合螺栓寿命的优化方案

针对连铸机结晶器水箱把合螺栓断裂问题进行了分析,找出了断裂发生的主要原因,通过优化把合螺栓结构、提升螺栓安装工艺,通过现场使用证明,大大提升了把合螺栓寿命,降低了维护成本,提升了产品质量。     

1200t冷剪曲轴压盖螺栓断裂分析

通过对螺栓断口形貌、硬度测试及金相组织等进行分析,表明作为重要受力螺栓,其加工形式不恰当,使螺栓表面存在环向刀痕及微小缺陷,引起应力集中是导致螺栓疲劳断裂的主要原因;另外热处理工艺不当使螺栓表层脱碳,降低抗疲劳性能也是螺栓疲劳断裂的原因之一。     

带钢轧机大型同步电机转子螺栓断裂原因分析

大型同步电机转子螺栓螺帽处断裂导致电机内部扫堂短路接地,通过对电机运行温度、轧钢工艺及电机螺栓质量等方向进行分析。发现电机转子螺栓存在质量问题,转子的运行环境、调速控制方式等多种因素构成了螺栓寿命降低及断裂的其他原因。同时介绍了防止螺栓断裂因素的预防及设备管理的措施。     

起重机高强度螺栓和标准节断裂原因分析

针对某起重机的高强度紧固螺栓和标准节的断裂,从断口宏、微观特征和显微组织的角度分析了断裂原因。研究表明:螺栓热处理工艺存在缺陷,螺栓调质组织中存在明显的贝氏体和网状铁素体组织,螺栓丝口根部存在较多的铁素体,这种组织的差异导致螺栓疲劳强度降低。在工作过程中的高应力作用下,应力集中的螺栓丝口根部逐渐萌生微裂纹,疲劳扩展,最终导致标准节整体断裂。     

进口轧机十字包螺栓研究与分析

宁钢热轧厂轧机十字包螺栓为日本进口非标螺栓,装机要求服役期限为18个月,实际工作14个月发生断裂,该十字包共4根螺栓,断裂了3根。从材质、热处理工艺等方面研究与分析失效原因。     

结晶器把合螺栓断裂原因分析与探讨

分析了结晶器螺栓断裂的原因，采取有效的防断裂措施，阐述了更好的结晶器铜板装配工艺方法。     

载重车轮动态弯曲疲劳试验用高强螺栓的断裂分析

载重车轮下线后一般需要进行动态弯曲疲劳试验。但连接车轮和弯曲疲劳试验机加载轴所使用的高强度螺栓在试验过程中出现了早期断裂的现象。通过宏观检验、断口分析、硬度测试和金相分析等方法对失效螺栓进行分析,确定了其断裂的主要原因为热处理不良、内部组织不良、外表面脆性大和循环作用力大于疲劳许用应力。通过对高强螺栓原材料的检验,并调整热处理工艺,在后续的试验过程中未出现螺栓断裂的情况。     

SWZ型万向接轴螺栓断裂原因分析

介绍了SWZ型万向接轴的结构及特点，通过分析螺栓结构和受力情况，认为接手键槽磨损、接轴运动特性影响螺栓寿命是造成螺栓断裂的主要原因，提出修复磨损键槽、定期更换螺栓、改进加工工艺等解决措施。     

铜记忆合金易断裂螺栓的工艺研究

废旧汽车及家电数量巨大,进行快速有效解体回收,成本大,费时长。对此,日本科研人员开发出加热到某个温度就可以自行断裂的新式螺栓,以提高废旧商品的回收效率,降低解体回收成本。本文也阐明了铜形状记忆合金拉丝加工工艺,并评价研究了易断裂螺栓的性能。     

轿车车轮紧固螺栓断裂失效分析

对轿车装置生产线使用的轮胎车轮紧固螺栓断裂事故进行了调研分析，追踪冶金生产，螺栓制造对失效件断口宏观及材料显向组织进行了科学分析和讨论，并采用批量工艺验证，从而找出了制造工艺不妥之处，提出了改进措施，获得满意的效果。     

脱脂与烧结工艺对WC-6Co-1TaC硬质合金显微结构与性能的影响

采用“溶剂脱脂+烧结”方法制备WC-6Co-1TaC硬质合金;研究了在同一烧结工艺下不同溶剂脱脂率对合金显微结构与性能的影响;以及在相同或相近的溶剂脱脂率下不同烧结工艺对合金显微结构与性能的影响;实验结果表明:高的溶剂脱脂率有利于获得更高性能的合金,溶剂脱脂率为41%的脱脂坯经烧结工艺A后较脱脂率为38%的试样抗弯强度提高16%,渗碳程度减轻,孔隙减小;烧结时在低温热脱脂阶段延长保温时间有利于残余粘结剂的排除和高温阶段通过进一步延长抽真空时间净化炉内气氛可以减轻渗碳程度从而提高合金性能。溶剂脱脂率为41%经烧结工艺B后制备的合金较经烧结工艺A制备的合金强度提高17%,达1684 MPa。     

耐压-抗折试验机的开发

将压力试验和抗折试验统一到同一设备上。此机器町准确控制加荷的速率．达到均匀加荷的目的；且对于不易破碎的耐火纤维制品，可用定位移的方法准确测量其耐压强度。     

A novel method to detect the water leakage from tuyere nose cooling circuit in blast furnace

The water cooled tuyere noses, through which hot blast is blown into the furnace, are exposed to very high temperature region of raceway inside the furnace. As a result the chances of rupture of cooling pipes within the tuyere nose are significantly high. The rupture causes water dripping into the furnace and if it continues and unnoticed for a prolonged period it lowers down the local raceway temperature and thus adversely affects the product hot metal and slag quality. Moreover, with heavy water leakage, there is a danger of explosion; monitoring of the cooling water is therefore essential. Despite the availability of water flow metre at each tuyere it is difficult to identify the leaking tuyere at the early stage unless the rupture size grows bigger and so the leakage. In several cases the furnace is forced to shut down to manually inspect the leakage occurring without prior knowledge of the exact tuyere number. Identification of water leakage at an early stage is therefore necessary to prevent process disturbances due to chilling of the furnace and avoid the unscheduled downtime for tuyere replacement. This paper presents a method to identify the water leakage from tuyere nose cooling circuit in blast furnace and the adverse effect of water leakage on the performance of the blast furnace. A system called water leak detection system is developed for different blast furnaces in Tata Steel Jamshedpur to monitor the water leakage through tuyere nose and identify the exact leaking tuyere based on a dimensionless number called leak detection factor.     

Formation kinetics and rupture strain of Ni-Cr-Fe alloy corrosion films formed in high-temperature water

Nickel alloys such as Alloy 600 undergo stress corrosion cracking (SCC) in pure water at temperatures between about 260 °C and the critical point. Increasing the level of Cr in Ni-Fe-Cr alloys increases SCC resistance in aerated and deaerated water. The mechanism for Cr influence is not understood. The effect of Cr composition on the in-situ oxide rupture strain and corrosion kinetics of Ni-9Fe-Cr alloys was determined experimentally, to evaluate whether the rupture-dissolution model for SCC can account for the effect of Cr on SCC. The alloy corrosion rate and corrosion product oxide microstructure and mechanical properties are strongly influenced by Cr composition. As Cr concentration increases from 5 to 30 pct, oxide rupture strains measured in pressurized water at 288 °C increase from about 8×10⁻⁴ to 2×10⁻³ mm/mm. Corrosion kinetics are parabolic; the corrosion rate first increases and then decreases as Cr increases from 5 to 39 pct. These observations are qualitatively consistent with a rupture-dissolution SCC mechanism. However, parametric modeling of the SCC growth process, applying available creep, oxide rupture strain, and corrosion kinetics data, indicates that the rupture-dissolution mechanism accounts for only a fraction of the effect of Cr on SCC resistance.     

Diffusion controlled stress rupture of polycrystalline materials

The high temperature stress rupture process in polycrystalline solids is examined in terms of grain boundary parting by vacancy condensation at the tip of a crack within the boundary. The gradient for diffusion of these defects is considered in the model to arise from the stress gradient in advance of the flaw tip. A rupture stress function is derived which is shown to closely describe the stress rupture behavior of a number of metals and high temperature alloys.     

Diffusion controlled stress rupture of polycrystalline materials

The high temperature stress rupture process in polycrystalline solids is examined in terms of grain boundary parting by vacancy condensation at the tip of a crack within the boundary. The gradient for diffusion of these defects is considered in the model to arise from the stress gradient in advance of the flaw tip. A rupture stress function is derived which is shown to closely describe the stress rupture behavior of a number of metals and high temperature alloys.     

预应力混凝土钢丝张拉断裂分析

针对高碳钢盘条加工的预应力混凝土钢丝在轨枕模型中张拉断裂问题,对张拉断裂、拉拔断裂及盘条试样进行检验分析,并结合工艺参数控制情况,分析断裂产生的原因,提出改进的措施。经生产应用,后续生产盘条加工的钢丝未出现张拉断裂现象。     

钼丝断裂行为研究

通过对钼丝生产过程中出现的断口实物样分析，阐明造成钼丝断裂的原因，提出钼丝生产用金属钼棒及其拉拔生产的关键工艺参数控制原理，达到降低钼丝断裂几率，提高综合成材率的目的。     

连铸坯横向断裂影响因素的分析

 对含Si低碳钢连铸坯发生的横向断裂缺陷进行了金相、扫描电镜检验分析及加热工艺模拟试验;对铸坯从钢水凝固到轧前加热断裂的热历程中所受外力及其与裂纹形成的关系进行了分析。检验分析结果表明：引起铸坯横向断裂的主要原因是浇注时钢水过热度高,凝固组织冷却慢,晶粒发生了严重的粗化,柱状晶间界的强度大大降低,使铸坯在弯曲矫直过程中形成内部裂纹,当再加热时,其热应力使内部裂纹进一步扩展而开裂。所以,控制好铸坯的浇注温度,提高铸坯中心等轴晶率,是防止含硅低碳钢连铸坯横向断裂的有效途径。     

Heat treatment effects on creep and rupture behavior of annealed 2.25 Cr-1 Mo steel

The strength of 2 1/4 Cr-1 Mo steel depends on the microstructure, which, in turn, de-pends on the heat treatment. In the fully annealed and isothermally annealed conditions, the microstructure is primarily proeutectoid ferrite with varying amounts of bainite and pearlite. The relative amounts of the latter constituents depend on the cooling rates during the anneal. The creep and rupture properties were determined for steel plates (from a single heat) given three different annealing treatments: two were fully annealed, but cooled at different rates from the austenitizing temperature, and the third was iso-thermally annealed. Properties were determined at 454, 510, and 566°C. At 454 and 510°C, the cooling rate had a significant effect on the creep and rupture properties, with the ma-terial cooled fastest being the strongest. Although at 510°C strengths at short rupture times differed widely, the properties approached a common value at longer rupture times. The properties differed very little at 566°C, even for short rupture times. The effect of heat treatment was concluded to be the result of interaction solid solution hardening, a dislocation-drag process. This process gave rise to nonclassical creep curves (as op-posed to classical curves with single primary, secondary, and tertiary stages). By examining the creep-curve shape, it was possible to interpret the heat treatment effects on the creep-rupture properties.