冷轧工作辊剥落的断裂力学分析

本文分析了冷轧辊的应力状态。按照冷连轧机工作辊的实际情况,考虑了轧制力、摩擦力和残余应力的影响。按照工作辊的剥落现象,将它归结为混合型裂纹的脆性断裂问题,运用应变能密度因子理论,计算了冷轧工作辊的临界裂纹尺寸。断裂力学原理解释了冷轧辊剥落原因,它与实际情况比较符合,同时,探索了提高冷轧辊使用寿命和降低成本的途径。     

冷轧工作辊表面剥落的失效分析

·轧辊表面产生剥落是冷轧工作辊的主要损坏形式,冷轧厂一直以来都非常重视这个问题,如何减少和预防冷轧工作辊表面剥落,提高其使用寿命,减少辊耗,对带钢的表面质量的提高和降低生产成本具有重大意义。     

浅析冷轧辊辊面剥落原因及改善

冷轧辊是冷轧设备中的重要零件之一,冷轧辊质量直接影响着冷轧发展。因此人们总希望轧辊质量完美无缺,但由于种种原因,轧辊还会出现各种形式的损坏,其中最常见的损坏形式有三种:辊身断裂、辊面磨损和辊面剥落。其中辊面剥落是冷轧辊报废的主要形式,有人统计,由于剥落而引起的报废占冷轧辊总消耗量的70％以上,所以     

关于冷轧辊的使用与维护

介绍了冷轧生产中所用冷轧辊的两种主要消耗类型 ,着重分析了冷轧辊产生剥落和断辊的原因及预防措施     

HC轧机支撑辊辊型技术研究

分析了冷轧HC轧机工作辊或中间辊圆弧部位存在局部磨损严重甚至轧辊局部剥落的原因,并重新设计支撑辊辊型,解决了轧辊局部磨损及局部剥落的问题。     

高性能冷轧辊的研究和选用

冷轧工作辊最常见的损坏是辊面裂纹和剥落，通过提高冷轧辊抗裂性的研究，选用了含Cr3%和5％的轧辊材料，采用强韧化热处理、电渣重溶等加工工艺，大大提高了冷轧辊耐裂纹能力，提高了冷轧辊使用寿命。     

浅析冷轧辊表面剥落原因及改善

介绍冷轧辊表面剥落产生的原因，及在轧辊的生产和使用中采取佬措施预防辊面剥落。     

提高冷轧辊抗事故性能的探讨

武钢冷轧工作辊在轧机上使用经常受到热冲击,发生粘辊、裂纹和剥落等较为严重的异常损坏。本文通过使用情况的分析,进行了冷轧工作辊附加回火工艺的试验,得到了较好的效果,为提高冷轧辊抗事故性能开辟了新的途径。     

冷轧工作辊的早期失效及预防措施

讨论了冷轧工作辊接触疲劳裂纹、剥落、夹杂物裂纹和磨损等失效形式。指出冷轧工作辊早期失效三要形式为剥落，其原因为局部过热和过载。使用轧辊时定期磨削去除微裂纹和表面无损探伤是提高轧辊使用寿命的关键措施。     

浅析冷轧辊的失效与维护

就宝钢冷轧薄板厂冷轧辊的使用状态介绍了冷轧辊的损耗类型,着重分析了冷轧辊产生剥落甚至爆辊的原因,同时提出了预防措施.     

车轮钢中的白点(二)

研究了车轮钢中白点对力学性能的影响.结果表明,当白点含量少且尺寸较小时,对拉伸性能没有影响,但使冲击韧性明显下降;当白点含量较多或尺寸较大时,使拉伸性能下降,但对断裂韧性没有影响.钢中的白点能增加疲劳扩展速率并使扩展速率发生波动.氢致滞后开裂与白点无关,而与氢原子有关.     

车轮钢中的白点(一)

研究了车轮钢中白点形成的机理以及白点对断口形貌的影响.结果表明,氢和空位聚集导致鼓泡形核和长大,随着鼓泡内氢气压力的升高,裂纹从鼓泡核壁形核、扩展导致白点形成.白点的断口为准解理,和氢致滞后开裂断口相同,含白点试样的断口形貌依赖于断裂方式和试样厚度.钢中的白点除了产生二次裂纹和局部准解理断面外,对各种断口形貌均没有明显的影响.     

IF钢合金化镀锌板镀层相结构对其性能影响研究的新进展

介绍了IF钢合金化镀锌板镀层相结构对其性能影响的一些最新研究成果，内容包括：相结构和铁含量对其冲压成型时的粉化性和剥离性的影响；对焊接性的影响；对镀层耐蚀性的影响及最佳相结构的选择。     

轧辊失效方式及其原因分析

介绍了轧辊存在剥落、断裂、裂纹等几种失效方式，并重点分析了轧辊剥落和断裂产生的机理，为分析生产实践中轧辊失效原因和采取相应改进措施以提高轧辊使用寿命提供了依据。     

The feeding value of dry-rolled and steam-flaked corn in finishing diets for feedlot cattle: influence of protein supplementation

We used 80 medium-framed yearling crossbred heifers (357 kg) in a 110-d trial to evaluate the influence of dietary protein level (11 vs 14%) on the feeding value of dry-rolled (DRC) and steam-flaked corn (SFC). All diets contained 1% urea; cottonseed meal (CSM) was the source of supplemental undegradable intake protein (UIP). Steam flaking corn reduced DMI (9%, P < .10) and increased (P < .01) feed efficiency (14%), dietary NEm (13%), and NEg (15%). Steam flaking increased the NEm by 17% and NEg by 19%. Supplemental CSM decreased (P < .10) feed efficiency (7%) and dietary NEm (4%) and NEg (6%). There were no treatment effects (P > .10) on carcass characteristics. Steam flaking corn increased (P < .05) fecal pH and reduced (P < .01) fecal starch. Supplemental CSM increased (P < .01) fecal pH and reduced (P < .01) fecal starch. Four Holstein steers (413 kg) were used in a 4 x 4 Latin square experiment to evaluate treatment effects on digestive function. Steam flaking corn increased (P < .05) flow of nonammonia N (11%, P < .05) and microbial N (15%, P < .01) to the duodenum. Supplemental CSM increased the flow of microbial N (6%, P < .01), feed N (21%, P < .10), and nonammonia N (12%, P < .05) to the duodenum. The UIP value of CSM was 28% for the DRC diet and 52% for the SFC diet. Steam flaking corn increased (P < .01) ruminal starch digestion (26%) and total tract digestibility of OM (17%), N (15%), starch (19%), and GE (17%). Steam flaking increased the DE value of corn by 21%. Supplemental CSM did not influence (P > .10) postruminal or total tract starch digestion. Supplemental CSM decreased (7%, P < .10) the DE value of the diet. We conclude that increasing the postruminal protein supply of a corn-based finishing diet beyond that provided by urea supplementation, alone, will not enhance starch digestion or the energy value of the diet.     

高锰钢铁路辙叉应力状态有限元分析

高锰钢(1．14％C、12．72％Mn)在使用过程中受到复杂的交变冲击载荷作用,表面出现剥落掉块现象而提前失效。用ANSYS 8．0软件对辙叉内部应力状态进行了有限元分析,得出辙叉表面垂直方向最大应力达5 381 MPa,水平方向应力2 450 MPa,硬化层深度15 mm;剪应力700 MPa,作用深度1．5 mm,剪应力加速铁路辙叉表面剥落。通过高锰钢微合金化,可细化晶粒提高材料韧性,延长辙叉使用寿命。     

汽车大梁钢粉状氧化铁皮剥落定量评价分析

大梁钢板热轧生产后直接用于汽车零件的冲压成型，其表面氧化铁皮的控制直接关系到冲压过程的稳定性及车间环境，因此开展汽车大梁钢粉状氧化铁皮剥落定量评价分析具有重要的理论与实践意义。针对大梁钢氧化铁粉剥落严重的问题，通过工业试验，开展了不同热轧终轧温度及卷取温度下氧化铁粉剥落量检测与成分分析，采用扫描电镜分析了氧化铁皮的层状结构与致密度，并定量研究了610L大梁钢热轧卷氧化铁皮中Fe₃O₄、FeO含量与氧化铁皮剥落的关系，得到氧化铁皮中Fe₃O₄质量分数为80%且FeO质量分数为3%左右时，610L钢的氧化铁皮最不容易脱落，形成不掉粉、高塑性的“黑皮钢”特性。针对后续冷加工过程中氧化铁皮剥落问题，通过三点弯曲试验进行了FeO含量与氧化铁粉剥落特性关系研究，发现FeO含量高的氧化铁粉在塑性弯曲的小变形阶段，其剥落多于FeO含量少的样品，但在大变形情况下，氧化铁粉剥落少于FeO含量较少的样品，其剥落质量差呈现出“先负后正”的特点。随着弯曲位移的增大，氧化铁皮剥落逐渐增多，且受压面氧化铁皮剥落多于受拉面。受拉面...     

超微碳化钼涂层的制备及其耐磨性能的研究

以Ni60为粘结金属,在其中分别加入5%(质量分数,下同)、10%和15%的超微碳化钼粉体,利用等离子喷涂方法在40Cr钢基体表面形成热喷涂层。通过对涂层在300 N压力、干磨2 h的试验条件下进行磨损试验,研究了超微碳化钼涂层的耐磨性能。试验结果表明,超微碳化钼粉体的加入显著提高了涂层的耐磨性,并且涂层的耐磨性随碳化钼粉体加入量的增加而提高,其原因主要在于超微碳化钼颗粒在涂层中的弥散强化和自润滑作用。     

The effect of grain source and grain processing on performance of feedlot cattle: a review

Effects of grain species and grain processing method on DMI, rate and efficiency of gain, and feeding value for cattle fed high concentrate diets were appraised by statistically compiling results from 605 comparisons from feeding trials published in North American journals and experiment station bulletins since 1974. Metabolizable energy (ME) values for each grain and processing method were calculated by quadratic procedures from DMI and animal performance. Averaged across processing methods, ME values for corn, milo, and wheat grain (3.40, 3.22, and 3.46 Mcal/kg DM) fell within 9% of ME estimates from NRC (1996) for beef cattle. In contrast, ME values for barley and oats grain (3.55 and 3.46 Mcal/kg DM) were 24% and 17% greater than NRC (1996) estimates. Compared with the dry rolled forms, high moisture corn and milo resulted in lower ADG and DMI. Compared with dry rolling, either steam rolling or flaking of corn, milo, and wheat decreased DMI without decreasing ADG and improved feed efficiency by 10, 15, and 10%, respectively. Compared with dry rolled grain, steam flaking increased (P < .05) body weight-adjusted ME of corn and milo grain by 15 and 21%, respectively; body weight-adjusted ME for whole corn was 9% greater (P < .05) than for rolled corn grain. Steam flaking was surprisingly effective (13%) at increasing (P < .05) the body weight-adjusted ME of wheat, but steam flaking failed to increase the ME of barley and oats. Higher moisture content of high-moisture corn decreased dry matter intake without depressing ADG and improved efficiency and increased ME of the grain. Compared with steam flakes of moderate thinness, processing milo or barley to a very thin flake tended to reduce ADG and failed to improve feed efficiency. The ideal roughage source and roughage moisture content for maximum ME and ADG varied with grain processing method. Feeding corn silage rather than alfalfa and wet rather than dry roughage depressed (P < .01) ADG of cattle and reduced (P < .01) body weight-adjusted ME of cattle fed high-moisture corn grain but tended to increase both with steam-flaked corn or wheat.