16Cr2Mo1Cu高铬铸铁在亚临界处理中硬化行为研究

研究了亚临界处理对16Cr2Mo1Cu高铬铸铁的组织转变和性能的影响,并利用X射线衍射分析、磁性法和硬度测定法分析了硬化机制.研究表明:16Cr2Mo1Cu高铬铸铁的铸态组织由残余奥氏体、马氏体和M7C3型共晶碳化物组成,其相对含量分别为77.0%,7.2%和15.8%;在亚临界处理过程中,基体组织中的残余奥氏体析出二次碳化物并在冷却过程中转变为马氏体,使该合金在560～600℃的亚临界处理过程中出现二次硬化;在适当的处理温度和保温时间下,16Cr2Mo1Cu高铬铸铁可得到最高的硬度.     

一种多元低合金高碳钢的热处理组织及硬度的研究

对一种低合金高碳钢(0.81C,0.65Cr,0.89W,0.54Mo,0.23V)热处理组织及硬度研究表明,该钢退火具有多类型碳化物(M3C,M7C3,M23C6,M6C和MC),在800～840℃区间退火,处于γ相低温区原碳化物部分溶解和新碳化物重新形核生长过程,使碳化物颗粒超细化,平均尺寸0.33～0.34 μm.淬火时,因M3C、M23C6溶解于奥氏体的速度较快,在840～860℃淬火时,硬度可达HRC63～65;未溶碳化物M6C和MC(VC)有利于马氏体细化,但因其数量较少,淬火最高温度不易超过880℃.该钢在低温和中温回火有较好的抗回火性能,并能有效地促进残余奥氏体转变.该钢热处理过程组织结构特征能较好地以相平衡热力学计算结果进行解释.     

Fe基非晶合金涂层的多晶型晶化过程研究

等离子喷涂Fe基非晶合金涂层的晶化温度在590℃左右.在高于晶化温度热处理时,涂层首先以多晶型晶化方式直接结晶形成亚稳的Fe23(c,B)6和Fe23B6化合物相.随热处理时间延长,Fe23(C,B)6和Fe23B6相发生分解,逐渐转变为更稳定的Fe3B相和Fe固溶体相.热处理温度越高,Fe23(C,B)6相和Fe23B6相的分解转变速度越快.随热处理温度升高或时间的延长,晶化涂层的硬度呈线性降低.经590℃,4h热处理后,涂层结晶形成纳米晶组织;经660℃,4h热处理后,涂层结晶形成树枝状晶组织,随热处理温度升高,涂层中扁平状粒子间结合增强并趋于熔合,晶粒发生长大.     

镍基合金粉末光束堆焊层的微观组织及强化机理

采用X射线衍射，SEM，EDAX及显微硬度和洛氏硬度等分析手段研究了含碳量为1．0％的NiCrBSi系自熔合金粉末光束堆焊层的微观组织及强化机理，结果表明，采用光束镍基合金粉末堆焊可在铁碳合金表面获得与基体冶金结合良好，无裂纹，轻度稀释的强化层，堆焊热输入对堆焊层稀释率及合金元素烧损的影响程度决定了堆焊层微观组织及物相组成，小热输入堆焊时，堆焊金属经度稀释（η=3.5%），其显微组织由少量初生的γ－Ni和大量的γ－Ni Bi3B Ni3Si三相共晶组成的亚共晶基底，以及在基底上分布着大量的Cr23C6,(Cr,Fe)7C3高硬度相组成，采用大热输入堆焊，堆焊金属稀释率达12％，堆焊层由大量的γ－（Fe,Ni0枝晶和少量γ－(Fe,Ni) M7C3共晶组成，在堆焊层中未发现一次碳化物的析出，在光束粉末堆焊层中大量高硬度M23C6,M7C3共晶组成，在堆焊层中未发现一次碳化物的析出，在光束粉末堆焊层中大量高硬度M23C6，M7C3型碳化物和Ni3B,Ni3Si共晶相的析出以及合金元素在γ相中的过饱和固溶是其是以强化的主要原因，与TIG堆焊相比，采用相近热输入所获得的光束粉末堆焊层的耐磨性能提高了3倍以上。     

Fe基非晶合金涂层在晶化过程中的硬度与组织变化

对等离子喷涂含Cr，Ni，W，Mo，C，Si等合金元素的Fe-B基非晶合金涂层进行了100～730℃不同温度4h热处理试验。差热分析结果表明，涂层的急剧结晶温度在590℃附近。热处理试验结果表明，在450℃以下热处理时，涂层仍基本保持非晶态，硬度变化不大。在450～610℃之间热处理时，随温度升高，涂层逐渐晶化，析出以Fe23(C，B)6和Fe23B6相为主的硬质相和富Fe相，在590℃左右获得晶粒尺寸约为20nm纳米晶组织，涂层硬度随温度升高急剧增大，在610℃左右硬度达到最大值，约1270HV。在630～730℃之间热处理时，富Fe相逐渐成为主要相，并有Fe23(C，B)6，Fe23B6，Fe2B和FeB等多种硬质硼化物相形成，晶粒尺寸随温度升高长大并形成树枝晶，涂层硬度逐渐降低。     

Cr-W-Mo-V高合金高碳钢的二次硬化特性及回火硬度计算

Cr-W-Mo-V高合金高碳钢高温回火时的二次硬化有两种形式，其一是最高回火硬度对应着一定的淬火温度和回火温度，且回火温度随淬火温度升高而升高；其二是最高回火硬度随淬火温度升高而升高，但回火温度基本不变。二次硬化的回火温度和最高回火硬度既与各类型碳化物沉淀的热力学和动力学有关，亦与残余奥氏体转变的进程有关，归根结底由淬火加热时的奥氏体基体成分决定的。依据奥氏体化温度下基体成分，提出基体成分配比碳公式为Cp=0、011W＋0．02Mo＋0．057Cr＋0．19V，二次硬化的回火硬度的计算公式为Hc=a（1＋b）／（0．0127a＋0．00267），其中a为基体碳饱和度，b为碳化物沉淀量的修正因子。     

奥氏体钢晶间腐蚀机理电子理论研究

采用递归法计算了奥氏体钢的杂质掺入能、格位能、亲和能等电子结构参数,建立电子参数与奥氏体钢晶间腐蚀关系,探索晶间腐蚀机理。研究表明：奥氏体钢中S和P由晶内向晶界扩散,恶化晶界稳定性,且使电子从晶界流向晶内,造成晶界与晶内产生电位差,形成微电偶结构,发生晶间腐蚀。C和Cr具有较强亲和力,能在奥氏体钢晶界形成（Cr,Fe）23C6相。Ni提高C的格位能,降低C在奥氏体中的固溶度,促进（Cr,Fe）23C6的形成与长大,增加奥氏体钢的晶间腐蚀敏感性。Nb和Ti降低C的格位能,抑制（Cr,Fe）23C6的形成,提高奥氏体钢的抗晶间腐蚀能力。     

急冷凝固FGH96合金粉末颗粒表面成分及预热处理对凝固组织的影响研究

对氩气雾化（AA）FGH96合金不同粒度急冷粉末颗粒表面进行俄歇电子能谱（AES）分析,对不同温度下进行预热处理粉末中碳化物的演变行为进行了研究,并讨论了粉末颗粒表面成分和预热处理时碳化物变化和转变的关系。结果表明：不同粒度FGH96合金原始粉末颗粒表面存在不同厚度C、O和Ti元素的污染层;经预热处理,粉末颗粒中MC＇型亚稳碳化物发生分解和转变,析出稳定MC、M23C6及M6C型碳化物,明显改变粉末颗粒内碳化物的稳定性和分布状态。     

Si的添加量对钨极氩弧堆焊铁基高碳高铬合金层组织结构及耐磨性的影响

为了改善铁基高碳高铬合金堆焊层的性能,在其堆焊合金粉中添加Si对Q235钢进行钨极氩弧堆焊,探讨Si含量对堆焊层组织结构、硬度和耐磨性的影响。结果表明:添加不同含量Si堆焊后堆焊层与母材的结合均为冶金结合,微观组织基本相似,均由网状碳化物(Cr7C3,Cr23C6)和残余奥氏体的共晶组织以及胞状残余奥氏体组织构成;Si含量从0增加到9.0%,网状组织的数量、胞状组织的显微硬度呈增加趋势,堆焊层的宏观硬度由55HRC增加到60 HRC,磨损失重由16.8 mg减小到1.1 mg。     

Fe-Cr-B-C堆焊合金的组织与耐磨性

采用药芯焊丝气体保护堆焊方法制备Fe-Cr-B-C堆焊合金,利用金相、SEM、XRD等方法,分析了不同硼含量对堆焊合金组织及硼化物形貌的影响。结果表明:Fe-12Cr-xB-0.1C合金的显微组织由铁素体+奥氏体+(Fe,Cr)2B+(Fe,Cr)23(B,C)6组成。当硼含量<3%(质量分数,下同)时,随着硼含量增加,硼化物形态逐渐由断续网状转变为网状;当硼含量≥3%时,随着硼含量增加,初生块状(Fe,Cr)2B数量逐渐增加,其尺寸和分布更均匀,硼化物主要呈块状、条状、鱼骨状、蜂窝状及菊花状分布。初晶(Fe,Cr)2B近似呈四边形柱状体,趋向垂直于堆焊层表面生长。当硼含量≤4%时,硼的增加能显著提高Fe-Cr-B-C堆焊合金的硬度及耐磨性。     

Effects of deep cryogenic treatment on property of 3Cr13Mo1V1.5 high chromium cast iron

Effects of deep cryogenic treatment on the microstructure, hardening behavior and abrasion resistance of 3Cr13Mo1V1.5 high chromium cast iron subjected to sub-critical treatment were investigated in this paper. The results show that deep cryogenic treatment after sub-critical treatment, the hardness and abrasion resistance of high chromium cast iron can be boosted obviously due to abundant retained austenite transforming into martensite and secondary carbides precipitation. In the course of sub-critical treatment with cryogenic treatment, the amount of precipitated secondary carbides was more than that in air cooling, and the secondary hardening peak advanced at a lower temperature. When abrasion resistance reach the maximal, there was about 20% retained austenite in microstructures. Cryogenic treatment can further reduce the austenite content but can not make retained austenite transform to martensite completely.     

Two-body abrasion wear mechanism of super bainitic steel

The abrasion wear resistance and wear mechanism of super bainitic steel austempered at different temperatures and time have been investigated by two-body abrasion testings, scanning electron microscopy, X-ray diffraction, transformation electron microscopy and electron backscattering diffraction. The results show that the two-body abrasion wear mechanism is predominantly micro-ploughing abrasion, and the wear resistance is decreased with increasing isothermal temperature which is attributed to the decreased hardness caused by a higher retained austenite content and the coarsening of the microstructure. The sample austempered at 230°C for 2?h with the higher amount of retained austenite and lower carbon concentration exhibits excellent wear resistance, and the transformation induced plasticity effect is observed during wear process which is beneficial for the improving of hardness and wear resistance.     

A study of microstructure and performance of cast Fe–8Cr–2B alloy

The effects of quenching temperature on microstructure and hardness of cast Fe–8Cr–2B alloy containing 0.3 wt% C, 2.0 wt% B, 8.0 wt% Cr, 0.6 wt% Si, and 0.8 wt% Mn were investigated by optical microscopy (OM), scanning electron microscopy (SEM), X‐ray diffraction (XRD), Rockwell hardness and Vickers microhardness testers. The experimental results indicate that the as‐cast microstructure of cast Fe–8Cr–2B alloy consists of M₂B (M = Fe, Cr), M₇(C, B)₃, α‐Fe, and γ‐Fe. The dendritic matrix composed of lath martensite mixed with a small amount of retained austenite, and the netlike boride M₂B distribute in the grain boundary. After quenching between 950 °C and 1100 °C, the netlike eutectic boride are broken up and a new phase‐M₂₃(C, B)₆ which is distributed in the shape of sphere or short rod‐like are precipitated from the matrix. Both the macrohardness and microhardness of specimens increase with the increasing quenching temperature. At about 1050 °C, the hardness reaches the maximum value. However, when the temperature exceeds 1050 °C, the hardness will decrease slightly. With the increase of tempering temperature, the hardness of cast Fe–8Cr–2B alloy quenching from 1050 °C decreases gradually and its impact toughness increases slightly. Crusher hammer made of cast Fe–8Cr–2B alloy quenching from 1050 °C and tempering from 300 °C has good application effect, and its service life improves by 150–180% than that of high manganese steel hammer.     

淬火温度对含铜5Cr15MoV马氏体不锈钢性能的影响

将含铜5Cr15MoV马氏体不锈钢在不同温度热处理并使用光学显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射(XRD)、透射电子显微镜(TEM)、硬度测试和电化学测试等手段对其表征,研究了淬火温度对其组织、硬度以及耐蚀性能的影响.结果 表明,铜元素的添加提高了材料中残余奥氏体的体积分数,而使其硬度降低.淬火后钢中的...     

Si元素对明弧堆焊奥氏体合金组织及耐磨性的影响

为获得以奥氏体为基体且韧性及耐磨性良好的明弧堆焊合金,采用药芯焊丝自保护明弧焊方法制备了以奥氏体为基体的Fe-C-Mn-Cr-Nb-V-Ti系多元耐磨合金,借助X射线衍射仪、扫描电镜及其附属能谱仪等测试手段,研究了Si含量对其组织和耐磨性的影响。结果表明:堆焊合金基体为γ-Fe,硬质相有(Fe,Cr,Mn,V)_(23)C_6,(Nb,Ti)C和(Fe,Cr)_3(C,B)等;当堆焊合金含1.5%Si(质量分数)时,出现了沿晶(Fe,Cr,Mn,V)_7C_3相;随着Si含量提高,沿晶界分布的(Fe,Cr,Mn,V)_(23)C_6型碳化物数量先增加然后减少,形态从树枝骨架状变为层片状离散孤立分布,胞状γ-Fe晶内原位析出的(Nb,Ti,V)C复合碳化物随之增大,堆焊合金耐磨性呈先提高后下降再提高的趋势;0.9%Si和1.5%Si堆焊合金试样的磨损质量损失低于一般高铬铸铁,具有良好的耐磨性和韧性,其磨损机制主要为磨粒的显微切削。     

过共晶高硼堆焊合金的显微组织及耐磨性

采用药芯焊丝埋弧堆焊方法制备含有0.1～1.0 C,4～13 Cr,2.5～3.2 V,2.2～3.8 B(质量分数/硼合金.借助光学显微镜、扫描电镜、X射线衍射等手段,研究其显微组织及硼化物分布形貌.结果表明:显微组织由铁素体+马氏体+残余奥氏体+M2B+M3(B,C)+V2C等组成,其初生M2B相的数量随硼含量而改...     

Effect of quenching on microstructure and wear‐resistance of Fe–10Cr–1.5B–2Al Alloy

Cast Fe–10Cr–1.5B–2Al alloy was quenched at different temperatures. The effects of quenching temperature on microstructure and hardness and wear‐resistance of Fe–10Cr–1.5B–2.0Al alloy were investigated by means of the optical microscopy, the scanning electron microscope, X‐ray diffraction, energy dispersive spectrometer, Vickers hardness and Rockwell hardness tester, and the MM‐200 block‐on‐ring wear testing machine under dry friction condition. The results indicate that the as‐cast microstructure of Fe–10Cr–1.5B–2.0Al alloy consists of ferrite, pearlite and netlike eutectics which are distributed in the grain boundary. The eutectics mainly include herringbone M₂B and chrysanthemum M₇(C, B)₃. The matrix gradually turns into single martensite with the increase of the quenching temperature. The type of borocarbides has no obvious change after quenching. The netlike boride almost totally fractures and transforms from the fish‐bone structure to the graininess. There is some retained austenite in the quenched structures when the quenching temperature is more than 1100 °C. When the quenching temperature is in a range of 1000 °C to 1100 °C, the hardness and wear resistance show a sharp increase with an increase of temperature, and show a slight decrease after surpassing 1100 °C.     

A Structural Study of High Cr Cast Iron as a Grinding Ball Material

In present paper, the 3-body abrasion andimpact fatigue resistance of a 12％Cr-2.65％C-1.4％Sihigh Cr cast iron are comprehensively evaluated.The results indicated that the lower the C contentof the martensitic matrix, the better the impactfatigue resistance of the iron. The retainedaustenite is always harmful to both 3-bodyabrasion and impact fatigue resistances. Thelow C content martensitic matrix free fromretained austenite is suitable for making grindingballs.     

Effects of carbide-forming elements on the response to thermal treatment of the X45Cr13 martensitic stainless steel

The effects of carbide-forming elements on the response to thermal treatment of the X45Cr13 martensitic stainless steel have been investigated. Heat treatments consisted of austenitizing for 60 s at temperatures ranging from 1000–1250 °C. The higher is the solution treatment temperature, the less M23C6 carbide is left out of solution in the austenite. As a result, the concentration of carbon and alloying elements in the martensite increases and, therefore, an increase in the hardness until a maximum value of 710 HV was found at austenitizing temperatures of 1120 and 1130 °C for the steels X45Cr13 and X45CrMoV14, respectively. At higher austenitizing temperatures, the presence of retained austenite was observed, which leads to a lowering of the hardness value. The higher amount of carbide-forming elements in the X45CrMoV14 determines an increase in retained austenite from 3 vol% to about 30 vol%. Thus, a drop in the hardness value from 710 to 680 and 585 for the steels X45Cr13 and X45CrMoV14, respectively, was found. © 1998 Kluwer Academic Publishers     

A Study of Microstructures and Properties of High‐Carbon Si‐Cr Cast Steel Containing Rare Earth and Titanium

The microstructure, tensile and impact behaviour of high‐carbon Si‐Cr cast steel containing rare earth (RE) and titanium have been determined after austempering. The additions of RE and titanium refined the primary austenite grain size resulting in improving toughness. The addition of silicon handicapped the formation of carbide and carbide‐free bainitic ferrite and carbon enriched retained austenite could be obtained in the austempering structures of high‐carbon Si‐Cr cast steel, which had excellent mechanical properties and abrasion resistance. Moreover, the basic tendency of the mechanical properties of high‐carbon Si‐Cr cast steel influenced by the austempering temperature was that the hardness and tensile strength reduced and the impact toughness and fracture toughness increased with increasing temperature. The comprehensive properties were the best while austempering at 330^oC.