Effect of deep cryogenic treatment on the properties of 80CrMo12 5 tool steel

The effect of deep cryogenic treatment on the mechanical properties of 80CrMo12 5 tool steel was investigated. Moreover, the effects of stabilization (holding at room temperature for some periods before deep cryogenic treatment) and tempering before deep cryogenic treatment were studied. The results show that deep cryogenic treatment can eliminate the retained austenite, making a better carbide distribution and a higher carbide amount. As a result, a remarkable improvement in wear resistance of cryogenically treated specimens is observed. Moreover, the ultimate tensile strength increases, and the toughness of the sample decreases. It is also found that both stabilization and tempering before deep cryogenic treatment decrease the wear resistance, hardness, and carbides homogeneity compared to the deep cryogenically treated samples. It is concluded that deep cryogenic treatment should be performed without any delay on samples after quenching to reach the highest wear resistance and hardness.     

残余奥氏体的形态和分布对9SiCr工具钢强韧性的影响

本文研究了残余奥氏体对Si-Cr钢(含碳量0.9％)的冲击韧性的影响,发现深冷处理后残余奥氏体呈透镜状或膜状并沿马氏体边界分布,多冲周次N值可以提高,模具寿命也可以增加3倍以上。在深冷处理过程中残余奥氏体转变成针状马氏体,而且块状残余奥氏体被针状马氏体分割,使残余奥氏体细化。9SiCr钢经不同时间深冷处理,其冲击韧性差别很大。     

残余奥氏体对高铬白口铸铁磨料磨损特性的影响

本文通过改变高铬白口铸铁(15Cr-2Mo-1Cu)的热处理工艺,得到一系列残余奥氏体数量在0～60％范围内变化的基体组织;考察了残余奥氏体对低应力、高应力和有冲击载荷存在的动载磨料磨损特性的影响;运用X射线新方法测定了各种磨损后残余奥氏体诱发马氏体转变的数量、层深及分布梯度.研究结果表明:残余奥氏体对耐磨性的影响与磨损系统和残余奥氏体的稳定性有关.     

Feasibility of new ladle-treated Hadfield steel for mining purposes

A debate has arisen over the possibility of using a new ladle-treated Hadfield steel instead of conventional heat-treated Hadfield steel in mining applications. This debate might be solved by identifying the differences between the mechanical properties and strain-hardening properties of conventional heat-treated Hadfield steel and its counterpart ladle-treated Hadfield steel. Tensile and compression tests demonstrated that the ductility of ladle-treated Hadfield steel is similar to that of conventional heat-treated steel. However, the strain-hardening property of the ladle-treated Hadfield steel is almost two times higher than that of the heat-treated Hadfield steel. The results of this study demonstrate that the improvement of the strain-hardening behavior is attributable to the low stacking-fault energy of the main austenite matrix, which results from the high segregation coefficient of carbon and manganese solutes of the main austenite matrix into the new eutectic phase. Superior wear abrasion resistance is a potential consequence of different strain-hardening properties under low and high loads.     

针织机三角耐磨性的研究

对国产和日本产的针织机三角进行了多项对比实验，分析讨论了化学成分、硬度和微观组织结构对其耐磨性的影响．结果表明钢的微观组织结构，如碳化物的类型、尺寸大小、形状系数、弥散度及残留奥氏体的含量对其耐磨性有很大的影响．国产针织机三角的合金元素含量比进口三角高得多，但其二次联化物的合量、碳化物的形状系数、弥散度以及残留奥氏体的含量都比日本三角低，这就是国产三角耐磨性低的原因．为国产三角的合理选材、改进热加工工艺提供了理论依据．     

激光相变硬化对轴承钢组织与性能的影响研究

本文对低温回火态Gcr15轴承钢的激光相变硬化处理进行了研究.试验了激光处理的工艺参数对硬化过程的显微组织、淬硬层的硬度变化、残余应力分布、残留奥氏体形貌与数量以及耐磨性能等的影响.结果表明:经激光相变硬化处理后,Gcr15钢的表面硬度可达HV1000以上,硬化层的显微组织为缺陷密度高的隐针马氏体,晶粒度为ASTM 14级,残留奥氏体约达20%,呈膜态分布于马氏体条片之间及碳化物周围,超细的碳化物非常弥散地分布着,表面层保持较大的压应力而耐磨性能明显提高.据此,可以认为激光相变硬化的强韧化机制是:晶粒细化强化、亚结构强化,弥散析出强化以及残留奥氏体强化等的综合贡献.     

温度对40Cr钢温挤压成形的摩擦--磨损性能影响

采用温挤压技术对40Cr钢进行成形试验,考察了不同温度下温挤压试样的摩擦-磨损行为.通过扫描电镜、能谱仪和X射线衍射仪分析了40Cr钢磨损后表面形貌、化学元素分布和物相组成,讨论了40Cr钢温挤压的磨损机理.结果表明,在挤压温度为550℃时试样晶粒尺寸细小,残余奥氏体含量较高,硬度最高,其磨损性能为最佳;而当温度为650℃和750℃时,晶粒尺寸较粗大,残余奥氏体含量降低.在5N载荷作用下,挤压温度为550℃时,摩擦因数为0.7667;当挤压温度达到650℃,摩擦因数为0.8587,提高了12.01%,磨损性能降低;750℃时,摩擦因数为0.8764,相比550℃提高了14.31%,磨损性能进一步变差;在550、650和750℃时,磨损形式主要为磨粒磨损.     

高碳低合金钢低温贝氏体组织及其耐磨性研究

设计了一种新的低温等温转变无碳化物贝氏体高碳低合金钢。对该钢低温等温淬火组织和干滑动摩擦磨损耐磨性及磨损机理进行研究,并与淬火+低温回火处理试样进行比较。结果表明,经1 000℃奥氏体化后在220℃盐浴中进行等温120 h的等温淬火处理,得到了由平均厚度约为120 nm的板条状贝氏体铁素体和薄膜状的残留奥氏体组成的无碳化物贝氏体组织,干滑动摩擦磨损相对耐磨性比回火马氏体组织提高19%,磨损机理为粘着磨损。     

Effect of deep cryogenic treatment on the formation of nano-sized carbides and the wear behavior of D2 tool steel

The effect of deep cryogenic treatment on the microstructure, hardness, and wear behavior of D2 tool steel was studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), hardness test, pin-on-disk wear test, and the reciprocating pin-on-flat wear test. The results show that deep cryogenic treatment eliminates retained austenite, makes a better carbide distribution, and increases the carbide content. Furthermore, some new nano-sized carbides form during the deep cryogenic treatment, thereby increasing the hardness and improving the wear behavior of the samples.     

9Cr5MoV钢的磁性分析与深冷处理

采用SLX-80深冷处理系统对9Cr5MoV钢进行冷处理,采用综合物理测试系统的振动样品磁强计选件(PPMS-VSM)测试样品的室温磁性。钢在930℃淬火态、-80℃和-120℃冷处理态,样品中残余奥氏体含量分别为13.5%,11.7%和10.1%,深冷处理(-120℃)较冷处理(-80℃)能更有效地减少钢中残余奥氏体。950℃淬火态钢测得最大硬度值(65HRC),淬火后-120℃深冷处理可使钢的硬度值提高至66HRC。950℃淬火再140℃低温回火后,-120℃深冷处理可使钢的硬度提高约1HRC。     

低碳高速钢渗碳

比较了低碳高速钢浅层渗碳经常规热处理后（１１７０℃和１０５０℃）的组织、硬度和耐磨性，讨论了不均匀奥氏体渗碳的扩散特点．生产应用表明，浅层渗碳明显提高了热磨损为主要失效模式的热度锻的使用寿命．     

提高高铬铸铁抛丸机叶片寿命的途径

本文对接近共晶成分的20%Cr和17%Cr的高铬铸铁,采用简便的定向凝固铸造工艺和改进的热处理工艺试制抛丸机叶片。在使用钢丸的工况下,所试制叶片的使用寿命达670小时,超过世界名牌产品瑞士GF叶片100%;在使用铁丸的工况下,所试制叶片的使用寿命达380小时,超过国内先进水平的叶片55%。叶片的实际运行试验和磨面分析结果表明,在使用铁丸的工况下,叶片主要是切削磨损,但反复冲击下材料的剥落也起着重要作用,提高叶片的硬度和降低残奥量,有利于耐磨性的提高;在使用钢丸的工况下,叶片的失效主要是由于反复冲击下材料的剥落,而切削所起的作用较轻微,降低残奥量和改善马氏体的韧性能有效地提高耐磨性。碳化物垂直于磨面的定向排列,亦有利于提高耐磨性。     

马氏体钢力学性能和耐磨性的关系

对自行研制的新型马氏体耐磨钢20Si2Ni3进行了Q-P-T(淬火-分配-回火)及传统淬火-回火(Q-T)热处理,用MLD-10型动载磨料磨损实验机比较在1.5J冲击能量、石英砂磨料条件下,20Si2Ni3钢和高锰钢ZGMn13的冲击磨料磨损性能,并用X射线测量磨损实验前后20Si2Ni3钢残余奥氏体量的变化,用扫描电镜(SEM)分析磨损机理。结果表明:经两种热处理工艺后的20Si2Ni3钢,其冲击磨料磨损性能均优于高锰钢。相比传统Q-T热处理工艺,经Q-P-T热处理后的20Si2Ni3钢,在保持较高硬度的同时,冲击韧性得到了较大提高;不同热处理工艺后,在硬度均约HRC45.5时,20Si2Ni3钢的冲击磨料磨损性能随着冲击韧性的增加而提高,磨损机理以显微犁削为主。     

淬火分配处理对高碳钢组织、力学性能和磨损性能的影响

The present work employed the X-ray diffraction, scanning electron microscopy, electron backscattered diffraction, and electron probe microanalysis techniques to identify the microstructural evolution and mechanical and abrasive behavior of high carbon steel during quenching-partitioning treatment with an aim to enhance the toughness and wear resistance of high carbon steel. Results showed that, with the increase in partitioning temperature from 250 to 400°C, the amount of retained austenite (RA) decreased resulting from the carbide precipitation effect after longer partitioning times. Moreover, the stability of RA generally increased because of the enhanced degree of carbon enrichment in RA. Given the factors affecting the toughness of high carbon steel, the stability of RA associated with size, carbon content, and morphology plays a significant role in determining the toughness of high carbon steel. The analysis of the wear resistance of samples with different mechanical properties shows that hardness is the primary factor affecting the wear resistance of high carbon steel, and the toughness is the secondary one.     

稀土在WC颗粒复合耐磨材料中的作用

为了提高ＷＣ硬质合金颗粒复合材料的耐磨性,向复合材料的金属基体中加入了不同数量的稀土。采用扫描电镜、Ｘ射线能谱仪、显微硬度计、台式冲击试验机以及销盘式磨损试验机等试验手段,对稀土加入量不同的几种ＷＣ硬质合金颗粒复合材料的金属基体进行了稀土分布及显微组织的分析,测定了基体组织的显微硬度及复合材料的韧性和耐磨性。研究结果表明,稀土富集于奥氏体与碳化物和奥氏体与共晶体两种界面处,少量固溶于奥氏体中。加入适量的稀土产生了明显的微合金化作用,使共晶组织显著细化,提高了金属基体的硬度和韧性以及复合材料的耐磨性。     

深冷处理对高速钢高低温力学性能的影响研究

研究了深冷处理和未深冷处理的试样在室温及高温下的力学性能 .结果表明 ,深冷处理试样的力学性能明显提高 ;深冷处理和未深冷处理试样的磨损表面形貌和垂直截面形貌有显著差异 ,说明它们有不同的磨损规律 ;通过X 射线衍射还发现 ,深冷处理可使马氏体轴比和碳含量下降 ,促使新相碳化物MC析出 .     

Microstructure and high-temperature wear properties of in situ TiC composite coatings by plasma transferred arc surface alloying on gray cast iron

In this work, an in situ synthesized TiC-reinforced metal matrix composite (MMC) coating of approximately 350–400μm thick-ness was fabricated on a gray cast iron (GCI) substrate by plasma transferred arc (PTA) surface alloying of Ti–Fe alloy powder. Microhard-ness tests showed that the surface hardness increased approximately four-fold after the alloying treatment. The microstructure of the MMC coating was mainly composed of residual austenite, acicular martensite, and eutectic ledeburite. Scanning electron microscopy (SEM) and X-ray diffraction analyzes revealed that the in situ TiC particles, which were formed by direct reaction of Ti with carbon originally contained in the GCI, was uniformly distributed at the boundary of residual austenite in the alloying zone. Pin-on-disc high-temperature wear tests were performed on samples both with and without the MMC coating at room temperature and at elevated temperatures (473 K and 623 K), and the wear behavior and mechanism were investigated. The results showed that, after the PTA alloying treatment, the wear resistance of the sam-ples improved significantly. On the basis of our analysis of the composite coatings by optical microscopy, SEM with energy-dispersive X-ray spectroscopy, and microhardness measurements, we attributed this improvement of wear resistance to the transformation of the microstruc-ture and to the presence of TiC particles.     

65Nb钢冷镦模具回火组织变化与耐磨性的关系

基体钢(65Nb)冷镦模具经超低温工艺处理后微观组织发生了变化,即从回火马氏体中析出碳化物微粒,残余奥氏体转变成马氏体并析出微细碳化物。这种组织变化可显著提高模具的耐磨性和冲击韧度,因而也大大延长了模具的使用寿命     

铬系白口铸铁腐蚀磨损特性的研究

本文研究了共晶碳化物数量在20—25％范围内,含铬量由2—24％,铸态及热处理态的铬系白口铸铁在不同介质条件下的腐蚀磨损特性.研究结果表明:在强酸性介质中,腐蚀是导致腐蚀磨损失重量增大的主要因素,含铬量较高的奥氏体有较好的腐蚀磨损抗力,碳化物存在没有任何益处;在弱酸性介质中,腐蚀与磨损共同对腐蚀磨损失重量起作用,提高基体含铬量,保持适当数量碳化物将有效地提高其腐蚀磨损抗力;在中性及碱性介质中,磨损是主要影响因素,提高基体硬度有助于腐蚀磨损抗力的提高.合金元素铜可降低基体腐蚀速度,促进基体钝化,且有利于腐蚀磨损抗力的改善.本文研究结果为杂质泵过流部件的选材提供了依据.     

中碳高硅铸钢的复合热处理工艺

研究了成分(wt.%)为0.62C,2.0Si,1.6Mn,0.99Cr的高硅铸钢经过复合热处理(球化退火+等温淬火)的组织和力学性能.利用olympus金相电子显微镜观察组织、扫描电子显微镜分析冲击断口形貌;测试了实验钢的洛氏硬度和冲击韧性.实验结果表明,试样经过球化退火工艺之后硬度变化的幅度不大,而冲击韧性有明显地提高,试样的组织主要为下贝氏体组织,并含有少量的奥氏体.在相同的球化退火工艺下,320℃等温淬火60min,试样的硬度和冲击韧性值都较高.