钛对D型石墨铸铁组织和性能的影响

研究了钛对灰铸铁组织和性能的影响。试验表明,不同含量的钛对灰铸铁组织和性能产生不同的影响。在一定含量范围内,钛促进灰铸铁D型石墨的形成,改善灰铸铁石墨形态,并提高灰铸铁的强度性能。对钛对灰铸铁组织和性能作用的机理提出了看法。     

D型石墨铸铁在600—700℃时抗氧化性的研究

试验了合金元素钛以及铸型冷却条件对灰铸铁抗氧化性的影响,研究了石墨大小和D型石墨的含量对灰铸铁抗氧化性的影响。试验结果表明:石墨越细小,灰铸铁的抗氧化性越好; D型石墨铸铁的抗氧化性优于A型石墨铸铁。     

钒钛对灰铸铁制动鼓组织性能的影响

钒、钛都是强碳化物形成元素。研究了钒、钛元素的加入,对灰铸铁制动鼓组织性能的影响。通过对普通制动鼓和加入0.17wt%钒、0.08wt%钛的钒钛制动鼓的金相及力学性能检测,结果表明,碳元素的扩散受到了阻碍,从而抑制了石墨的长大,使得A型石墨含量减少,D型石墨含量增多,石墨的长度变短,削弱了A型石墨对基体的割裂作用。同时,钒和钛生成的碳化物能起到细化晶粒和强化基体组织的作用,显著提高了灰铸铁的抗拉强度及耐磨性,使制动鼓的使用性能大大提高。     

D型石墨形成条件的研究

本文通过测定加钛、稀土镁铁水中活性氧含量,对凝固过程中的试样液淬和使铁水在石墨型中凝固,研究了D型石墨的形成。把D型石墨的产生条件分为三类:过冷作用,铁水物化性质改变和两者综合作用。     

高强度D型石墨铸铁的研究进展

综述了灰铸铁中产生D型石墨的原因，D型石墨对灰铸铁性能的影响以及D型石墨灰铸铁的应用。国内外的研究表明：深过冷，在灰铸铁中加入提高过冷度的合金元素（钛，铝，锑，碲，稀土元素等）或者二者的结合都会促进生成D型石墨；D型石墨灰铸铁具有较高的强度，较好的抗氧化性，抗生长性，抗热疲劳性和耐磨性；D型石墨灰铸铁已经广泛用于生产玻璃模具，压缩机缸体，压缩机曲轴等铸件。笔者还介绍了采用钒钛生铁生产的D型石墨合金铸铁凸轮轴的性能特点及其应用情况。     

D型石墨的研究进展与展望

对铸铁中D型石墨形成的条件和工艺要求,影响生长的各种因素以及D型石墨对铸铁性能的影响和D型石墨铸铁的应用进行了综述。最后,展望了D型石墨的研究手段,建议利用先进的高温共聚焦激光扫描显微镜对其进行更加全面深刻的研究。     

正确认识Ti在钢铁中的作用

通过介绍Ti的物理化学性质及其化合物的性能特点,说明Ti在不同钢种中的作用和含量范围;适量的Ti在铸铁中具有脱氧去气、防止氮气孔产生以及促进D型石墨产生等作用.详细阐述了钛对铸铁的影响,有助于铸造企业在铸件生产中正确认识Ti的作用.     

对灰铸铁中D型石墨的评价

对灰铸铁中 D 型石墨的认识一直存在分歧、影啊正确评价 D 型石墨的原因是多方面的,奥氏体技晶常与 D 型石墨同时出现是其中的原因之一。由于 CE 相同时,枝晶数量多少对灰铸铁强度有明显影响.因而以前那些没有考虑枝晶的影响所作出的对 D 型石墨的评价是欠说服力的。文中通过控制枝晶数量,基体组织和石墨类型,对不同 CE 下 A 型石墨、D 型石墨及枝晶对强度的影响作了评估,并通过断口分析认为。D 型石墨对基体危害较 A 型石墨小,在高 CE 下,D 型石墨是更加理想的石墨组织。     

硅、锰对D型石墨铸铁的影响

D型石墨的组织形貌有利于在铸铁基体组织中生成铁素体相。在砂型铸造条件下,硅的稳定铁素体的作用能在D型石墨铸铁中得到充分的发挥,故硅含量的增加将引起D型石墨铸铁机械强度大幅度的下降。锰含量的增加能促进珠光体的形成而提高D型石墨铸铁的机械强度,但其硬度值上升的幅度较小。砂型铸造高强度D型石墨铸铁显示了其优越的机械性能和良好的铸造性能,加工性能。     

Al、Ti、Si/C对D型石墨铸铁强度的影响

一、前言D 型石墨铸铁(以下简称 D 墨铸铁)不仅比 A 型石墨铸铁有更高的强度且有更高的切削加工性和致密性,是制造空压机、制冷机等部件的理想材料。它已越来越为人们所关注。我们在本刊1986年第一期发表的“D 型石墨含量对灰铸铁强度的影响”(以下简称上文)一文中已较详细地论述了 D 墨铸铁的组织特点及其形成机理和其含量与铸铁强度的关系。本文在此基础上根据 D 墨铸     

Influence of graphite morphology on dry sliding wear of flake graphite cast irons

Abstract

Four flaky graphite cast irons of different graphite structures with a pearlitic matrix were prepared to clarify the graphite structure's influence on the dry sliding wear property. Two melts of cast iron with different carbon contents were solidified at two different cooling rates. The four resultant samples had type A flaky graphite or type D eutectic graphite structure with different graphite volume fractions and fully pearlitic matrixes. A pin on the disc type wear test evaluated the four samples' dry sliding wear properties. Results showed that the type D graphite structure wore down faster than the type A graphite structure did. The type of graphite morphology influenced the specimen wear rate as strongly as the graphite volume fraction did in flaky graphite cast irons of this experimental range.     

Titanium in the rapidly cooled hypereutectic gray iron

The effect of titanium on the structure and properties of a rapidly cooled hypereutectic cast gray iron has been studied on the example of permanent mold (PM) casting. A microstructure study showed that titanium is a relatively strong element in controlling solidification structure by increasing undercooling and thus promoting type D graphite. The effectiveness of titanium additions depends on the base iron carbon equivalent (CE) with more pronounced changes in iron with a lower CE. The undercooling ability of the titanium decreases after exceeding a certain level. Increasing titanium from 0.09–0.12% slightly increases undercooling in iron with lower CE, but this effect was reduced in a more strongly hypereutectic iron. Alloying with titanium generally improves tensile strength, but the effectiveness of titanium additions also depends on the base iron CE range. Scanning electron microscope (SEM) studies revealed that most of the titanium-containing compounds were located in the metallic matrix: titanium carbides have been found in pearlite, while titanium nitrides and carbonitrides were located in ferrite. The presence of large amounts of extremely hard titanium-containing compounds, which often appear with steadite in a relatively high phosphorous content PM gray iron, amplifies the negative effect of titanium on machinability. This study suggests that for optimal combination of tensile strength/microstructure with good machinability, the titanium content in PM gray iron should not exceed 0.075%.     

V、Ti合金化对玻璃模具材料抗氧化及耐热疲劳性的影响

通过测试不同V/Ti比条件下蠕墨铸铁玻璃模具材料的抗氧化及热疲劳性能,研究了蠕墨铸铁的钒、钛合金化工艺,并探讨了影响这些性能的因素.结果表明,在V、Ti变化范围内,V/Ti比为1.63时蠕墨铸铁具有较均匀的铁素体基体+蠕虫状石墨组织,以及良好的热物性.     

Influence of alloying additions on microstructure and thermal properties in compact graphite irons

Abstract

Nineteen compacted graphite cast irons were investigated to determine how alloying additions affect the thermal transport properties and microstructure. All melts were based on one chemical composition and alloying elements were added to obtain melts with variation in magnesium, silicon, carbon, copper, tin, chromium and molybdenum. Increasing amounts of magnesium resulted in a further compaction of the graphite particles, reducing the thermal conductivity. Large amounts of silicon resulted in a fully ferritic metal matrix. Silicon also formed solid solution with iron which had a deteriorating effect on the thermal conductivity, i.e. the larger amount of silicon the lower the thermal conductivity. Copper and tin promoted formation of pearlite that had worse thermal properties compared to ferrite. Increasing amount of ferrite generally had a positive influence of the thermal conductivity. Chromium and molybdenum were carbide forming elements and carbides had a negative influence on the thermal conductivity.     

稀土对D型石墨铸铁强化机理的研究

通过试验研究,发现微量稀土能促进D型石墨铸铁中初晶奥氏体骨架的生长,对强化基体组织有一定的作用。微量稀土能细化D型石墨,石墨数量增多,石墨生长前端钝化、分枝、花瓣状形态也有所改善,大大减轻了石墨对基体的破坏作用,从而提高D型石墨铸铁的力学性能。     

废钢加入量对镍奥氏体铸铁组织和性能的影响

研究了废钢加入量对镍奥氏体灰铸铁组织和性能的影响。试验结果表明，随着废钢加入量的增加，奥氏体枝晶发达、石墨细化、硬度提高；在相同废钢加入量条件下，随着壁厚的增加，凝固冷却速度降低，石墨变得粗大，硬度降低；另外，细小均匀分布的A型片状石墨有利于降低试样的加工表面粗糙度。     

镁对含砷锡铅钛球铁组织和性能的影响

研究了原铁液含硫量和镁加入量对含砷、锡、铅、钛球墨铸铁组织和力学性能的影响。结果表明，球墨铸铁中有砷、锡、铅、钛等微量元素共存时，镁的合适加入量范围缩小；硫加剧微量元素对力学性能的有害影响，镁不能完全中和与消除硫对力学性能的危害作用；降低镁的加入量有利于生成铁素体；异形石墨严重损害球墨铸铁的力学性能。     

球墨铸铁中的奥氏体枝晶及球墨铸铁的偏析--球墨铸铁基础理论的最新发展(三)

介绍了球墨铸铁中奥氏体枝晶的形成，分类及影响因素，指出奥氏体枝晶排列方向的控制对进一步挖掘球铁力学性能潜力的意义，同时阐述了溶质元素，凝固速度等因素对球铁偏析的影响规律。