二次碳化物的析出和转变对15Cr-1Mo-1.5V高铬铸铁硬化行为的影响

为了揭示高铬耐磨铸铁硬化的微观机制，提高其使用性能，采用光学显微镜、透射电镜和X射线衍射研究15Cr—1Mo—1．5V高铬铸铁中二次碳化物的析出和转变对其亚临界处理硬化行为的影响。研究结果表明，在833K进行亚临界处理时，出现两个硬化峰。残余奥氏体发生马氏体转变和二次碳化物(Fe，Cr)23C6的析出是第一个硬化峰形成的原因；MoC、(Cr，V)2C的析出导致材料的硬化则引起了第二个硬化峰形成。随后发生了(Fe，Cr)23C6向M3C型碳化物的原位转变，导致珠光体基体的形成，从而使材料硬度降低。     

Relations of abrasion resistance and hardness of 16Cr-3C white irons with retained austenite content

The relationship between the retained austenite content of the matrix in 16Cr-3C white irons and the abrasion resistance was investigated. The results show that: (1) the abrasion resistance can be improved by sub-critical heat treatment, which could be attributed to the decrease of the retained austenite content; (2) both the abrasion resistance and hardness can be improved by controlling the retained austenite content below 20%-30% and arrive at the maximum when the retained austenite content is reduced to about 10%; (3) the abrasion resistance decreases abruptly once the retained austenite content is lower than 10%, which stems from both the in situ transformation of (Fe, Cr)23C6 to M3C carbides and the formation of pearlitic matrix.     

马氏体不锈钢等离子堆焊铁基合金组织及磨损性能

为了研究马氏体不锈钢的表面性能,采用等离子堆焊技术在Z5CND16-04不锈钢表面制备铁基合金堆焊层.采用扫描电子显微镜、能谱仪、X射线衍射仪、显微硬度计及销盘磨损实验机等检测设备,对堆焊层的组织结构、成分、硬度和磨损性能进行了研究.结果表明,铁基合金堆焊层主要由α-Fe、(Fe,Cr,Mo)7C3和(Fe,Cr,Mo)23C6相组成,添加稀土元素后相组成无明显变化.铁基合金堆焊层的硬度和耐磨性均明显高于马氏体不锈钢基材.添加适量的CeO2后,明显细化了堆焊层的显微组织.     

稀土镁对高铬铸铁变质效果的研究

为了研究RE—Mg对Cr15Mo3高铬铸铁铸态及热处理态组织、冲击韧性、硬度、耐磨性等性能的影响规律,提出RE—Mg变质处理工艺的改进方案,通过对比实验的方法,验证了改进方案的可行性．结果表明：铸态未变质的高铬铸铁组织中,奥氏体含量大,碳化物呈粗大网状分布,基体被撕裂;变质后碳化物的网断裂,变细成为鱼骨状,对基体的割裂作用大大减小,基体的连续程度增加．RE—Mg变质处理可使Cr15Mo3高铬铸铁的硬度、冲击韧性、耐磨性都得到提高．本实验条件下,当变质剂加入量WRE-Mg=1．5％时变质效果最好,材料的综合性能最佳．     

Relationship of microstructure transformation and hardening behavior of type 17-4 PH stainless steel

The relationship between the microstructure transformation of type 17-4 PH stainless steel and the aging hardening behavior was investigated. The results showed that, when 17-4 PH stainless steel aging at 595℃, the bulk hardness of samples attains its peak value （42.5 HRC） for about 20 min, and then decreases at all time. TEM revealed the microstructure corresponding with peak hardness is that the fine spheroid-shape copper with the fcc crystal structure and the fiber-shape secondary carbide M23C6 precipitated from the lath martensite matrix. Both precipitations of copper and M23C6 are the reasons for strengthening of the alloy at this temperature. With the extension of holding time at this temperature, the copper and secondary carbide grow and lose the coherent relationship with the matrix, so the bulk hardness of samples decreases.     

提高低铬白口铸铁耐磨性的研究

低铬白口铸铁中 M_3C 型碳化物的硬度具有方向性,在碳化物纤维横截面上硬度为 HV1425,纵截面上硬度为 HV935.利用较简易的方法制得含2.5%C,3.7%Cr低铬铸铁定向凝固的三体磨损和冲击疲劳试样。试验结果表明,M_3C 型碳化物定向排列以后,不论在硬磨料(石英砂)还是在软磨料(玻璃砂)条件下,相对于砂型铸造试样耐磨性均有提高。碳化物定向排列后,对试样冲击疲劳性能没有影响。     

渣浆泵用钢基表面耐磨复合材料的研究

以ZG45为基体，以多种合金粉末作为合金化原料，通过铸渗工艺制备出较为理想的渣浆泵用铁基表面耐磨材料．铸件合金层厚度均匀，基体组织为树枝状的奥氏体，增强相为二次碳化物(Cr，Fe)7C3和渗碳体型碳化物Fe3W3C，在合金化过程中，主要是铁液向合金层渗透，铬向母材的渗透也有，但量很少，合金层与母材的结合良好，属于冶金结合，其冲击磨损性能和硬度都有很大提高，耐磨性比ZG45提高了6．5倍，硬度从合金层到基体逐渐降低，合金层硬度比ZG45提高了3倍左右。     

Physical Characteristics of Plasma Cladding Fe-Cr-Nb-Si-Mo Alloy Cladding Layers on Different Substrates

A plasma cladding experiment was carried out to investigate the characteristics(surface hardness,microstructure,friction,wear properties from different substrates to the cladding layer and the bond strength) of plasma cladding Fe-Cr-Nb-Si-Mo alloy cladding layers on different substrates.In order to improve the abrasion resistance of the scraper middle trough,the plasma cladding technique was used to clad the alloy ceramic powder Ig7 on the surface of the middle trough NM450,WH60A,Hardox450,and Weartuf450 to create Fe/Cr/Nb/Mo/ V cladding layer.Based on the experiment results,the microstructure,friction and wear properties of the four cladding layers were analyzed,and the bond strength between the cladding layer and the substrate was also tested.The experimental results show that the main phases of the four cladding layers are martensite and all kinds of metal carbides ((Nb,Mo)C,VC,and Cr_7C_3).WH60A surface cladding layer has shown good friction and wear properties.     

Effect of electromagnetic stirring on the microstructure and wear behavior of iron-based composite coatings

The effect of electromagnetic stirring on the microstructure and wear behavior of coatings has been investigated. A series of iron-based coatings were fabricated by the plasma-transferred arc cladding process by applying different magnetic field currents. The microstructure and wear resistance of the composite coatings were characterized by scanning electron microscope (SEM), energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD), and wet sand rubber wheel abrasion tester. The experimental re- sults showed that the microstructure of the coatings was mainly the γ-Fe matrix and (Cr, Fe)7C3 carbide reinforced phase. The coatings were metallurgically bonded to the substrate. With increasing magnetic field current, the amount of the block-like (Cr, Fe)7C3 carbide reinforced phase increased at first, reached a local maximum, and then decreased sharply. When the magnetic field current reached 3 A, the block-like (Cr, Fe)7C3 carbides with high volume fraction were uniformly distributed in the matrix and the coating displayed a high microhardness and an excellent wear resistance under the wear test condition.     

Cr3C2对等离子钴基堆焊层组织及性能的影响

采用等离子堆焊技术在低碳钢表面制备钴基合金堆焊层(Co40)及添加质量分数20%和40%Cr3C2的钴基合金复合堆焊层(Co40+20%Cr3C2,Co40+40%Cr3C2)。利用光学显微镜、扫描电镜、X射线衍射仪以及磨损实验机等研究不同添加量的Cr3C2对钴基合金堆焊层组织和耐磨性能的影响。结果表明:Co40堆焊层由γ-Co和Cr23C6组成;添加Cr3C2粉末后,堆焊层出现未熔的Cr3C2和Cr7C3及Cr23C6相,且明显改变了其组织特征,Co40+20%Cr3C2堆焊层仍以亚共晶方式结晶,但其组织得到明显的细化和均匀化,而Co40+40%Cr3C2堆焊层转变为过共晶方式结晶,其组织由大量初生碳化物和枝晶组织组成;Co40+Cr3C2复合堆焊层的硬度和耐磨性较Co40堆焊层均得到显著提高,且随着Cr3C2添加量的增加而相应提高。     

热处理对高铬铸铁磨损特性的影响

高铬铸铁具有优良的耐磨性,主要是由于其基体为马氏体组织,碳化物类型为六方晶系的（Ｆｅ,Ｃｒ）７Ｃ３,碳化物呈六角棒状、针状、条状分布,显著地改善了材质的力学性能．煤粉对管道的磨损,属于软磨粒低应力的磨料磨损,这种高铬铸铁用于此工况下能发挥出其优良的性能．经金属Ｘ射线分析证明碳化物是（Ｆｅ,Ｃｒ）７Ｃ３,通过透射电镜分析,发现其基体组织为奥氏体、板条（位错）马氏体与孪晶马氏体．用电子探针对金相组织中的黑色区进行了分析,发现此处贫铬而易被腐蚀．通过磨损试验证明高铬铸铁耐磨性好,成本低,与稀土高铬镍氮相比,成本降低６０％,与钨铬合金相比,成本降低７０％．     

低铬钛钒耐磨白口铸铁中钒钛的作用

研究钒钛元素对该铸铁机械性能的影响,进而探讨了钒钛在基体和碳化物中的分布情况,发现钒主要溶于碳化物中形成(Fe·Cr·V·Mn)_3C型碳化物,而且改善了碳化物的亚结构,同时,钒钛与变质作用相互促进,改善了晶界状态,从而提高了铸铁的耐磨性。     

Effects of heat treatment on microstructure and mechanical properties of Fe-Co-Ni-Cr-Mo-C alloy

A kind of Fe-Co-Ni-Cr-Mo-C alloy was designed for valve seat use. The effects of the quenching temperature, tempering time and tempering temperature on the mechanical properties and microstructure of the alloy were investigated. The results show that the hardness decreases, while tensile strength (σb), transverse rupture strength (σbb) and impact toughness(Kit) increase after the alloy is quenched and tempered. The best complex property (σb, 446 MPa; σbb ,793 MPa; Kic, 2.96 J/cm2 ) can be obtained when the alloy is quenched at 1 100 ℃ and tempered at 650 ℃. The results of X-ray diffraction and energy dispersive X-ray analysis (EDX) show that the major strengthening phases are carbides such as (Fe, Cr)7 C3 and Fe2 MoC. The obvious secondary hardening appears when the alloy is tempered at 550 ℃, which results from the precipitated carbides of Cr and Mo in the alloy from the matrix and the heat-resistant retained austenite .     

Influences of copper on solidification structure and hardening behavior of high chromium cast irons

The influences of copper on microstructure and the hardening behavior of high chromium cast irons subjected to sub-critical treatment were investigated. The results show that the microstructure of the as-cast high chromium cast irons consists of retained austenite, martensite and M1C3 type eutectic carbide. When copper is added into high chromium cast irons, austenite and carbide contents are increased. The increased addition of copper content from 0% to 1.84% leads to the increase of austenite and carbide from 15.9% and 20. 0% to 61.0% and 35.5% , respectively. In the process of sub-critical treatment, the retained austenite in the matrix can be precipitated into secondary carbides and then transforms into martensite in cooling process, which causes the secondary hardening of the alloy under sub-critical treatment. High chromium cast irons containing copper in sub-critical treatment appear the second hardening curve peak due to the precipitation of copper from supersaturated matrix.     

新型低铬铸态抗磨球墨铸铁变质处理

研究了具有石墨＋碳化物＋珠光体组织的新型低铬抗磨铸铁变质处理作用效果．试验结果表明，原铁水中加入含Ｓｉ、Ｃａ、Ｍｏ、Ｖ元素的复合变质剂后，能够细化组织，改善碳化物形态，固溶强化基体，使铸铁ＨＲＣ值及αｋ值增加，耐磨性提高．     

Cr27抗磨白口铸铁的研究及生产应用

采用热模拟技术,对于铸件不同模数,就Ｃｒ２７抗磨白口铸铁中的锰、钼、镍（铜）等 合金元素对铸铁硬度的影响进行了研究．对于中等壁厚铸件,找到了合适的Ｃｒ２７抗磨白口的 化学成分和热处理规范．用研制的合金成分生产杂质泵铸件,其使用寿命长．     

降Nb,V,Ni添加Mn对HD钢二次硬化的影响

利用透射电镜和化学相分析研究了降低Nb,V,Ni含量以及添加Mn对HD钢二次硬化的影响。研究结果表明,降低Nb,V,Ni后对二次硬化温度影响不大,但硬度升高。添加Mn可使二次硬化温度提前,并使硬度进一步升高。二次硬化主要由V_4C_3和Mo_2C引起。回火时沿孪晶界析出片状渗碳体。     

药芯焊丝明弧堆焊Fe-Cr-C-B合金组织及耐磨性

为了提高堆焊合金的耐磨性,利用明弧堆焊方法将自保护耐磨堆焊药芯焊丝熔覆在Q235基体金属表面,制备得到Fe-Cr-C-B耐磨堆焊合金.采用金相显微镜、扫描电子显微镜、X射线衍射仪、硬度计和磨料磨损试验机对堆焊层的组织、硬度和耐磨性进行了分析.结果表明,堆焊层主要由马氏体、少量残余奥氏体、M_3(C,B)、M_(23)(C,B)6和M_7(C,B)3相组成.随着B质量分数的增大,基体组织转变为马氏体,共晶硬质相增多,并呈连续网状分布在基体组织周围.当B的质量分数为3%时,堆焊层的耐磨性达到最佳,其硬度为61. 5 HRC,磨损量为0. 362 9 g.     

添加Mo元素对Fe40Co40Zr9B10Ge1合金晶化过程和磁性能影响

采用单辊快淬法制备Fe40Co40Zr9B10Ge1和Fe40Co40Zr5Mo4B10Ge1两种非晶合金,并在不同温度下对其进行热处理。利用XRD和VSM两种仪器对合金的微观结构和磁性能进行测试分析,研究Mo添加对Fe40Co40Zr9B10Ge1合金晶化过程和磁性能的影响。结果表明,两种合金在晶化初期均有α-Fe(Co)相从非晶基体析出,但高温热处理后的晶化产物不同,Mo添加减少了高温金属化合物的含量。低于675℃热处理,Mo添加降低了合金晶化过程中析出α-Fe(Co)相的晶粒尺寸和合金的矫顽力。     

激光熔覆Cr3C2/Fe复合涂层的组织与磨损性能

采用5kWCO2连续激光器在低碳钢表面激光熔覆Fe基合金涂层（Fe55）及添加20%Cr3C（2质量分数）的Fe基合金复合涂层（Cr3C2/Fe）,研究了两种涂层的组织结构、显微硬度及耐滑动磨损性能。结果表明,Fe55涂层以亚共晶方式结晶,在初生柱状固溶体枝晶间存在大量的网状共晶组织。Cr3C2/Fe涂层中Cr3C2大部分溶解,原Fe55涂层中初生柱状固溶体枝晶产生等轴化,枝晶组织也明显细化。激光熔覆Fe55涂层主要由α-Fe和Cr23C6组成,Cr3C2/Fe涂层的主要组成相为γ-Fe;α-Fe,Cr23C6以及未熔Cr3C2。激光熔覆Cr3C2/Fe涂层的硬度和耐磨性明显优于Fe55涂层。