Effect of RE Modification and Heat Treatment on Formation and Growth of Thermal Fatigue Crack in Wear Resistant Cast Iron Containing Low Alloy

The formation and growth of thermal fatigue crack and the function of RE and heat treatment in wear resistance of cast iron containing low alloy were investigated,and it was analyzed in view of the activation energy for the crack′s propagation. The results show that the thermal fatigue cracks are mainly generated at eutectic carbides,and the cracks are grown by themselves spreading and joining each other. RE can improve the eutectic carbide′s morphology,inhibit the generation and propagation of thermal fatigue cracks,therefore,promote the activation energy for the crack′s propagation,and especially,which is more noticeable in case of the RE modification in combination with heat treatment.

Influence of Rare Earth on Wear Resistance of Wear Resistant Cast Iron Containing Low Alloy

The Influence of RE on wear resistance of wear resistant cast iron containing low alloy was studied by means of slide wear and impact wear test. Moreover, its microstructure and characteristics of wearing surface was analyzed. The experimental results show that RE can improve the wear resistance of wear resistant cast iron containing low alloy, especially for impact wear resistance. The optimum wear resistance of wear resistant cast iron containing low alloy modified by RE of 0.046% can be obtained by normalization at 950 ℃ for 3 h. Moreover, the coordinated effect of rare earths and heat treatment was also revealed in this paper.

Formation and Growth of Granular Carbides in Multiple Alloying Wear Resistant Cast Iron Containing RE Through Hot Deformation

The granular carbides formed from hot deformation in multiple alloying wear resistant cast iron were studied through the observation by means of optical microscope, SEM and TEM. The experimental results show that carbides with large size are formed from original short rhabdoid carbides existing in cast, those with small size directly nucleate in the matrix. Carbides with the size between the above are formed from precipitation induced by hot deformation. The bigger the deformation is, the larger the number of microsized granular carbides is. The mechanisms of nucleation and growth of granular carbides and the function of RE were discussed.

Influence of Heating Temperature on Property of Low Chromium Wear Resistant Cast Iron Containing Rare Earth

The influence of heating temperature on mechanical properties of low chromium wear resistant cast iron containing rare earth elements was studied by means of metallographic examination, scanning electron microscopic examination and mechanical property test. The experimental results show that heating temperature has great effect on impact toughness (α_k), bending fatigue (σ_(bb)) and relative toughness (σ_(bb)×f), but little effect on hardness (HRC). When the specimen was held at 960 ℃ for 3 h, it has better comprehensive mechanical properties, and the reason and regularity of the change for mechanical properties of the cast iron were reviewed.

Effect of Cooling Rate after hot Deformation on Structure and Mechanical Properties of Low Alloy Wear Resistance Cast iron

The effect of cooling rate after 40% hot deformation on structure and mechanical properties of low alloy wear resistance cast iron was investigated by metallographic, scanning electron microscopes and detection of properties. The results show that for the cast steel after deformed, the amount of granular carbides of precipitation during the cooling decreased with the increase of the cooling rate, but the hardness was obviously enhanced, as a result, better mechanical properties will be obtained by force air cooling(cooling rate is about 7 ℃·s-1). And the reason of the change for structure and mechanical properties of the cast steel were analyzed.

Effect of Cooling Rate on Structure and Properties of Wear-Resistant Low Chromium Cast Iron after Hot Deformation

The effect of cooling rate on structure and properties of wear-resistant low chromium cast iron after 40% hot deformation was investigated by metallographic and scanning electron microscope. The results show that the cooling rate is closely related to the structure and properties, and for the cast iron, the best comprehensive mechanical properties were obtained by forced air cooling with a cooling rate as about 7 ℃/s. The reason and regularity for the change of mechanical properties were analyzed.

Properties of Cross-Rolled Low Alloy White Cast Iron Grinding Ball

The low-energy, multi-impact fracture resistance and the abrasiveness of the cross-rolled low alloy white cast iron grinding balls were studied after heat treatments at residual rolling temperature. Moreover, the means by which they are damaged and characters of the wear surface were analyzed. The results show that high resistance to impact fracture and high abrasiveness can be achieved after appropriate heat treatment at residual rolling temperature. This kind of heat treatment technology has several advantages under low impact and hard abrasive. These results are very useful for determining the optimized heat treatment technology at residual rolling temperatures.

LASER ALLOYING ON CHROMIUM-COATED SURFACE OF NODULAR CAST IRON

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Effect of Rolling Process on Microstructure and Wear Properties of High Carbon Equivalent Gray Cast Iron

Rolling process based on the plastic deformation as a surface strengthening treatment was employed,aiming to improve the wear resistance ability and functional performance of the high carbon equivalent gray cast iron(HCEGCI).The microstructures and tribological performance of the untreated and rolled samples were characterized.In addition,the wear mechanism of HCEGCI samples was also studied via pin-on-disc tests.The experimental results show that the as-rolled samples possess the structure-refined layer of 15μm and work-hardened layer of 0.13 mm.In comparison with the surface hardness of untreated samples,the surface hardness of as-rolled samples increases by 84.6%(from 240HV0.1 to 443HV0.1)and the residual compressive stresses existed within the range of 0.2 mm.The wear rates of as-rolled samples were decreased by 38.4%,37.5%,and 44.4%under different loads of 5 N,10 N,and 15 N,respectively.The wear characteristics of the untreated samples mainly exhibit the peeling wear coupled with partial adhesive and abrasive wear.However,as for the as-rolled samples,the adhesive wear was limited by the structure-refined layer and the micro-crack propagation was controlled by the work-hardened layer.Therefore,the wear resistance of as-rolled samples can be improved significantly due to the low wearing degree of the friction contact zone.

合金灰口铸铁气缸套组织形貌与耐磨性研究

针对5种成分和组织的灰口铸铁气缸套,包括2种贝氏体铸铁气缸套和3种珠光体铸铁气缸套,全面分析了其成分、相组成及硬度等材料特性,将喷钼活塞环与5种合金灰口铸铁气缸套对磨,通过比较各配对副的摩擦磨损性能,获得了喷钼活塞环与5种合金灰口铸铁气缸套的匹配规律。研究结果表明:5种气缸套材料均为由硬质相、基体和石墨构成的复合耐磨结构,各组分的性能、分布及其配比,是决定耐磨性的关键因素。珠光体基体气缸套的磨损量相对稳定,气缸套与活塞环的相对磨损量正常;铸态贝氏体气缸套磨损较轻,配对活塞环的磨损量比珠光体气缸套大;贝氏体气缸套和活塞环的磨损均量很小。

基于文献计量学的高铬铸铁组织及性能研究进展

耐磨材料在工业发展中起到关键作用,其中高铬铸铁因其耐磨性能优异、成本较低得到了快速发展。高铬铸铁的研究主要集中在制备工艺、组织与性能调控、耐磨性等几个方面。本研究借助文献计量学方法对近年来的研究进行了梳理,介绍了研究的侧重点,并从耐磨性研究的最新进展、合金成分和热处理对组织及性能的影响,总结了近年来的研究现状。研究表明,M_(7)C_(3)型碳化物是高铬铸铁组织中最重要的强化相,能够显著提高基体的强度和耐磨性能。对高铬铸铁进行热处理,能够细化晶粒,提高硬度和耐磨性。另外,通过添加合金元素或者加入强化相也能提高高铬铸铁的性能,例如,添加Ti_(2)AlC后材料的力学性能明显提高。总之,对高铬铸铁的制备工艺、组织与性能调控、耐磨性等方面进行研究,有助于优化其性能并扩大其应用领域。

铸型对中碳低合金耐磨钢硬韧性和耐磨性的影响

采用SEM、XRD、冲击试验机和动载冲击磨料磨损试验机等,研究了三种不同冷却速度铸型下铸造锤头用中碳低合金耐磨钢的显微组织、硬度、冲击韧性和耐磨性。结果表明,三种试样显微组织均由回火马氏体、碳化物和残余奥氏体组成,且使用金属激冷铸型制成的钢,回火马氏体更加细小。对比石英砂铸型,使用金属激冷铸型的钢试样洛氏硬度、冲击韧性和耐磨性提升2.7%、16.1%以及14.6%。冷却速度高的铸型,有利于钢组织细化,同时提高硬度和耐磨性。

ZTA增强高铬铸铁的制备工艺和性能研究的现状

氧化锆韧化氧化铝(zirconia toughened alumina, ZTA)是一种陶瓷材料,可添加于高铬铸铁以提高其硬度、比强度、耐磨性、塑性和韧性等性能。综述了目前ZTA增强高铬铸铁制备工艺和性能研究的状况,制备工艺包括铸渗法、烧结法、铸造法、堆焊法和复合法,性能包括界面性能、耐磨粒磨损性能、摩擦磨损和冲蚀磨损性能及其通过合金化进一步改善。

Molybdenum alloying in cast iron and steel

Metal casting is an important manufacturing technology for efficiently producing massive components with complex shape.A large share of industrial castings is made from iron and steel alloys,combining attractive properties and low production cost.Upgrading of properties in cast iron and steel is mainly achieved by alloying and in fewer cases by heat treatment.Molybdenum is an important alloying element in that respect,increasing strength,hardness and toughness.It also facilitates particular heat treatments such as austempering.The paper describes the metallurgical functionality of molybdenum alloying in iron-based castings and demonstrates its effectiveness for applications in the automotive and mining industry.

硼对低合金灰铸铁性能的影响

硼在灰铸铁中能够形成硬质相的硼碳化物,当硼加入量控制在0.02%~0.10%时,可显著增加灰铸铁的耐磨性能。以低合金灰铸铁为研究对象,通过改变加入无水硼砂的含量来控制铸铁中硼的含量(0~40 ppm),通过直读光谱仪、光学显微镜、万能拉伸试验机等设备,对其组织和性能进行分析。研究结果表明,微量的硼使得灰铸铁金相中存在少量的铁素体,对于模数类似于Y50试块时,硼由7 ppm提高至20 ppm时,其抗拉强度降低15 MPa、硬度降低5.5 HBW。

QT600-5高耐磨性下汽缸铸件熔炼工艺优化

为提高筒式柴油打桩机下汽缸铸件耐磨性,本文分析下汽缸铸件的技术要求及铸造难点,采用材质为QT600-5生产、通过优化熔炼工艺:(1)严格控制铸件化学成分,并加入0.3%~0.5%Mn+0.5%~0.55%Cu+0.3%~0.5%Mo复合合金化;(2)采用冲入法球化处理,多次孕育的熔炼工艺。结果表明:生产出来的铸件力学性能符合客户要求、且具有优异的耐磨性,经客户反馈,使用寿命大幅度提高。

40铬钢表面加碳激光合金化处理

对 4 0铬钢进行表面加碳激光合金化处理 ,得到深 0 .2 5～ 0 .35mm的白口铸铁层 ,白口铸铁层组织呈梯度变化 ,晶粒明显细化 ,显微硬度高达 12 0 0HV0 .3 以上。热影响相变区组织为马氏体 ,并存在有针状马氏体到隐晶马氏体的分层 ,硬度为 710～ 780HV0 .3 ,比常规淬火明显提高。采用高的激光密度、快的扫描速度 ,有助于晶粒的细化 ,从而使硬度提高。磨损实验表明 ,白口铁层的磨损性能比常规淬火样品提高约 5 0 %。

新型中碳多元低合金稀土耐磨钢衬板的研制和应用

介绍了新型耐磨铸钢衬板的化学成分、熔炼、复合变质处理、热处理工艺以及装机运行试验。新材料合金元素含量低,不含镍、钛等贵重合金元素,价格低廉,熔炼容易控制。铸件热处理后,经空冷淬火和低温回火,硬度可达HRC58以上,冲击韧度达22J/cm2以上,耐磨性达到高锰钢(ZGMn13)衬板的2 1倍。