Effects of Rare Earths on Toughness of 31Mn2SiRE Wear-Resistance Cast Steel

The toughness of 31Mn2SiRE wear-resistance cast steel were increased by means of RE compound modification and high temperature austenitizing. The results show that the microstructures can be refined, needle and network ferrite are eliminated, the dislocation density and the quantity of dislocated martensite are increased remarkably, and the shape and distribution of inclusions are improved by the addition of RE. Therefore, the mechanical properties of the modified steel can be greatly increased, especially the toughness (αK) by 44%, yield strength (σs) by 10%, and elongation (δ5) by 42%.     

数字化制模新技术

数字化制模技术是将三维CAD模型直接转化成为铸造用模的新技术。文中介绍了华中科技大学开发的HRP系列数字化制模技术的原理及制模工艺。与传统制模方法相比 ,具有制模速度快、精度高、质量好、价格便宜等优点。文中还以制作轿车制动器卡钳体模样、搅拌叶片模样、蜗壳凸样为例说明了运用数字化制模新技术的优点     

Effects of solidification structure on fatigue crack initiation and fatigue strength in Al−Si−Mg cast alloys

Rotating-bending uniaxial fatigue tests and micro-fatigue crack initiation tests were carried out using a permanent mold cast (PMC) and semi-solid die cast (SDC) with Al−7%Si−0.35%Mg composition in order to examine the relationship between solidification structures and fatigue behaviors. The crack length was measured using a replication method. Fatigue strength was improved in SDC, which was almost consistent with the predicted fatigue strength using the size of Si particle cluster. Resistance to fatigue crack initiation and fatigue strength were improved in SDC owing to the finer Si cluster and to higher ultimate tensile strength. Fatigue crack in PMC was preferentially initiated at pores. For SDC, the fatigue crack was initiated at the Si particle/matrix interface, and then sucessively grew along eutectic cell boundaries.     

钻孔灌注桩施工中常见质量事故的控制和防治

介绍了钻孔灌注桩成孔质量的影响因素 ,详细叙述了钢筋笼的制作和吊放处理步骤 ,阐述了断桩发生的原因 ,提出了具体的防治措施 ,经实践效果良好     

Model of Primary Austenite Dendrite Structure in Hypoeutectic Cast Iron

Ｉｔｗａｓｒｅｐｏｒｔｅｄ[1] ｔｈａｔｔｈｅｍｉｃｒｏ ｓｔｅｒｅｏｓｔｒｕｃｔｕｒｅｏｆｐｒｉｍａｒｙａｕｓｔｅｎｉｔｅｉｎｃａｓｔｉｒｏｎｃｏｎｓｉｓｔｓｏｆｐｒｉｍａｒｙｓｔｅｍｓａｎｄｓｅｃｏｎｄａｒｙａｒｍｓｔｈａｔ ｇｒｏｗａｃｃｏｒｄｉｎｇｔｏｄｅｎｄｒｉｔｅｃｒｙｓｔａｌｓｂｒａｎｃｈｒｕｌｅ ,ａｎｄｓｏｍｅｏｆｐｒｉｍａｒｙａｕｓｔｅｎｉｔｅｅｖｅｎｈａｖｅｔｈｉｒｄａｒｍｓ .ＭｉｙａｋｅＨｅｔａｌ[2 ]ｐｒｏｐｏｓｅｄａｃｏｎｃｅｐｔｏｆｒｅｇｉｏｎｍｏｄｅｌｂｙｓｔｕｄｙｉｎｇ…     

厚断面球铁的声速

论述了影响厚断面球铁声速和声波衰减的各种因素。指出，必须在应力状态下同时考核声速和声波衰减，以作为判别厚断面球铁材质的一种手段。     

灰铸铁石墨形态的研究

文本研究了化学成份与冷却速度及孕育处理对灰铸铁石、墨形态的影响．并对形成的地B、C、D、E、F等六种衣铸铁石墨形态的形成条件作了讨论．     

Centrifugal Casting of High Speed Steel/Nodular Cast Iron Compound Roll Collar

Ｈｉｇｈ ｓｐｅｅｄｓｔｅｅｌ (ＨＳＳ) ,ｉｓｃｈａｒａｃｔｅｒｉｚｅｄｂｙｅｘ ｃｅｌｌｅｎｔｈａｒｄｎｅｓｓ ,ｗｅａｒｒｅｓｉｓｔａｎｃｅ ,ａｎｄ ｇｏｏｄｒｅｄｈａｒｄｎｅｓｓ .Ｒｅｃｅｎｔｌｙ ,ＨＳＳｉｓａｐｐｌｉｅｄｔｏｍａｎｕｆａｃｔｕｒｅｈｏｔｒｏｌｌｉｎｇｒｏｌｌｓｔｏｐｒｏｄｕｃｅｓｔｒｉｐｓｏｆｇｏｏｄｓｈａｐｅａｎｄｓｍａｌｌｃｒｏｗｎｗｉｔｈｅｘｔｅｎｄｅｄｒｏｌｌｓｅｒｖｉｃｅｌｉｆｅ[1,2 ] .ＴｈｅＨＳＳｉｓａｐｐｌｉｅｄｔｏｍａｎｕｆａｃｔｕｒｅｒｏｌｌｃｏｌｌａｒｆｏｒ…     

曲轴激光喷丸强化试验研究

采用实验的方法,研究了激光冲击强化对175A型柴油机曲轴疲劳寿命的影响,取得了激光冲击强化试验条件下曲轴过渡圆角处残余应力场的数据。并将激光冲击强化工艺效果和曲轴滚压强化效果做了对比性分析,结果表明：虽然激光冲击强化效果不如曲轴滚压强化,但考虑到激光工艺参数精确可控、加工质量好、成本低以及可避免滚压强化所造成的表面疲劳、撕痕等,激光冲击强化工艺可望代替滚压强化成为新型的曲轴强化手段。通过此类激光冲击强化强化实验可优化激光冲击的相关参数,使曲轴过渡圆角产生有利的残余应力场。     

谈影响钻孔灌注桩承载力的因素

根据目前我国钻孔灌注桩的特点，从施工工艺方面，对控制沉渣、孔壁泥层过厚的问题进行了探讨，提出了合理、有效的措施，以确保桩基础承载力的正常发挥。