高速线材导卫辊轮新材料研究

研究了多元合金化材料(在低高速钢中添加V,Nb,N,Re等元素)的组织结构和性能.结果表明,由于添加元素Nb推迟α-Fe的再结晶温度,添加W,Mo,V,Nb,C,N形成复合碳、氮化物等因素,经1250℃淬火,550℃3次回火2 h,试验钢有明显的二次硬化效果,硬度HRC 64.8.550℃保温16 h后的硬度为HRC 62.6,有很好的热稳定性.耐磨性接近于普通高速钢,W,Mo含量仅为普通高速钢的50%,是一种节能型高性能耐磨材料.     

50CrV低温二次硬化机理的探讨

设计了低温回火工艺，使50CrV钢的硬度提高，通过对比实验和采用透射电镜，探讨了低温二次硬化产生的机理，结果表明，低温回火时VC的弥散折出导致了50CrV钢的硬度升高，微合金钢中强碳化物形成元素Nb,V,Ti的沉淀强化和固溶强化引起低温二次硬化。     

亚临界热处理对含V高铬铸铁组织和硬度的影响

研究了不同的亚临界热处理温度和保温时间对含V高铬铸铁组织和硬度的影响,结果表明,通过亚临界热处理可使高铬铸铁产生二次硬化现象.在500～620℃进行亚临界热处理时,随着亚临界处理温度的升高和保温时间的延长,开始析出细小、弥散分布的二次碳化物.当热处理温度为540℃和保温时间为4 h时硬度达到62.4HRC,从而使材料的综合性能得到改善,温度太高或保温时间太长,都会使高铬铸铁的硬度下降.     

价电子结构与合金元素对NiAl力学性能的影响

运用固体与分子经验电子理论,计算了添加几种常用合金元素M(M=Cr,Mn,Fe,Co,Cu)的合金(NiM)Al相空间价电子结构,并采用相结构因子nA、ρLV表征和评判了合金元素M对NiAl金属间化合物塑性和硬度的影响。研究结果表明,采用宏合金化的方法虽然可以提高合金的硬度,却降低了合金的塑性。合金化后NiAl硬度增加的次序为(Ni0.875Mn0.125)Al>(Ni0.875Co0.125)Al>(Ni0.875Fe0.125)Al>(Ni0.875Cr0.125)Al>(Ni0.875Cu0.125)Al>NiAl,塑性降低次序则与硬度增加次序相反。     

Ni52.5Mn23.5Ga23.6Tb0.4磁性形状记忆合金马氏体相变和磁感生应变的研究

研究多晶合金Ni52.5Mn23.5Ga24的马氏体相变特征和磁感生应变性能,分析了稀土元素Tb对合金马氏体相变和磁性能的影响.研究结果表明,添加Tb使合金Ni52.5Mn23.5Ga24的马氏体相变温度提高到室温以上,并且降低了合金的温度滞后,在一定压力的作用下合金磁感生应变值增大.     

DD99单晶高温合金的高温组织演化研究

为了研究DD99镍基单晶高温合金的高温组织变化规律,通过高温热处理炉对DD99单晶高温合金进行了不同加热温度和保温时间的试验.采用场发射扫描电镜和显微硬度计分别对不同热处理状态的试样进行组织观察和显微硬度的测试.结果表明:随着温度的升高,保温时间的延长,DD99中的γ′相会发生回熔、连接及合并,尺寸不断增加,然后在γ基体通道中形成二次的颗粒状γ′相,该二次相会随温度的升高逐渐长大.二次γ′相的长大程度和Al、Nb等元素的扩散密切相关.性能试验也表明DD99单晶高温合金在保温100h后的试样随加热温度升高存在着明显的变化趋势,即硬度先降低后升高.     

Mn对铸造K325合金凝固组织和元素偏析的影响

采用光学显微镜、扫描电镜(SEM)和电子探针(EPMA)技术,研究了Mn含量对铸造K325高温合金凝固组织和元素偏析的影响。研究结果表明,Mn元素添加对合金晶粒度和二次枝晶间距无明显影响,却明显促进Nb、Mo元素偏聚于枝晶间,增大合金的偏析倾向。Mn元素的添加,使得Mn元素由正偏析元素变为负偏析元素,但Mn元素对合金铸态组织中第二相析出行为并无明显影响。     

价电子结构与合金元素对NiAI力学性能的影响

运用固体与分子经验电子理论,计算了添加几种常用合金元素M（M—Cr,Mn,Fe,Co,Cu）的合金（NiM）Al相空间价电子结构,并采用相结构因子nA、pv^L表征和评判了合金元素M对NiA1金属间化合物塑性和硬度的影响。研究结果表明,采用宏合金化的方法虽然可以提高合金的硬度,却降低了合金的塑性。合金化后NiA1硬度增加的次序为（Ni0.875Mn0．125）Al〉（Ni0．875Co0．125）Al〉（Ni0．875 Fe0．125）Al〉（Ni0．875Cr0．125）Al〉（Ni0.875 Cu0.125）Al〉NiA1,塑性降低次序则与硬度增加次序相反。     

用V.D.R试验方法研究低合金高强度钢埋弧焊时合金元素对结晶裂纹敏感性的影响

本文在国内首次应用变形速率连续可变式结晶裂纹试验方法(Continuously Variable Deforma-tion Rate Cracking Test简称V.D.R试验方法),研究了低合金高强度钢埋弧焊时,合金元素对焊缝金属结晶裂纹敏感性的影响。针对日本WEL—TEN60～80钢含多种合金元素的特点。研究了Mn、SiCr、Mo、V、Ti、Ni、Nb、Cu、B等元素对裂纹的影响,并得到了结论。结果表明:Mn、Cr、V、Ti在一定范围内是降低结晶裂纹敏感性的元素,而Ni、Si、B、Nb是增大结晶裂纹敏感性的元素。Mo、Cu、虽也有增加结晶裂纹敏感性,但影响较小。试验结果还表明了V.D.R试验和横向可变拘束试验结果的一致性。 本试验成果为研制Wel—Ten60—80新钢种焊接材料和可焊性试验提供了理论依据。     

钒对7Cr14铸钢组织与性能的影响

研究了V对7Cr14铸钢组织与性能的影响。结果表明，在7Cr14中加入1．O％V后，其硬度没有降低，但提高了回火稳定性、细化组织：回火后能产生明显的二次硬化效果．显著提高了其抗冲击磨损性能及磨粒磨损性能。     

Elevated-temperature properties of one long-life high-strength gun steel

The hardness, tensile strength and impact toughness of one quenched and tempered steel with nominal composition of Fe0.25C-3.0Cr-3.0Mo-0.6Ni-0. 1Nb (mass fraction) both at room temperature and at elevated temperatures were investigated in order to develop high-strength steel for long-life gun barrel use. It is found that the steel has lower decrease rate of tensile strength at elevated temperature in comparison with the commonly used G4335V high-strength gun steel, which contains higher Ni and lower Cr and Mo contents. The high elevated-temperature strength of the steel is attributed to the strong secondary hardening effect and high tempering softening resistance caused by the tempering precipitation of fine Mo-rich M2C carbides in the α-Fe matrix. The experimental steel is not susceptible to secondary hardening embrittlement, meanwhile, its room-temperature impact energy is much higher than the normal requirement of impact toughness for high strength gun steels. Therefore, the steel is suitable for production of long-life high-strength gun barrels with the combination of superior elevated-temperature strength and good impact toughness.     

改善42CrMo钢硬度与耐磨性的研究

将合金元素Mn,Cr,Mo,Nb加入42CrMo钢中熔炼后,选择退火、油淬及回火的热处理方式．回火温度为380℃时,提高单个合金元素的百分含量,cr含量可达到1．51％,硬度46．8HRC,磨损率0．214．同时,综合提高了合金元素Mn,Cr,Mo,Nb的含量．回火温度350℃,Nb对42CrMo的硬度和耐磨性的影响比Mo明显,而回火温度410℃时,Mo的影响更为明显．合金元素Mn,Cr,Mo,Nb质量分数分别为0．60％,1．40％,0．30％,0．07％时,回火温度为410℃,42CrMo钢的硬度达到46．2HRC,磨损率0．216．     

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。     

Influence of secondary carbide precipitation and transformation on abrasion resistance of a 3Cr15Mo1V1.5 white iron

The relationship between the secondary carbide precipitation and transformation of the 3Cr15Mo1V1.5 white iron and abrasion resistance was investigated by using optical microscope （OM）, transmission electron microscopy （TEM） and X-ray diffrac- tion （XRD）. The results show that the properties of secondary carbides precipitated at holding stage play an important role in the abrasion resistance. After certain holding time at 833 K subcritical treatment, the grainy （Fe, Cr）23C6 carbide precipitated and the fresh martensite transformed at the holding stage for 3Cr15Mo1V1.5 white iron improve the bulk hardness and abrasion resistance of the alloy. Prolonging holding time, MoC and （Cr, V）2C precipitations cause the secondary hardening peak and the corresponding better abrasion resistance. Finally, granular （Fe, Cr）23C6 carbide in situ transforms into laminar M3C carbide and the matrix structure transforms into pearlitic matrix. These changes weaken hardness and abrasion resistance of the alloy sharply.     

Effect of homogenization treatment on microstrucmre and properties of Al-Mg-Mn-Sc-Zr alloy

The effect of homogenization on the hardness, tensile properties, electrical conductivity and microstructure of as-cast Al-6Mg-0.4Mn-0.25Sc-0.12Zr alloy was studied. The results show that during homogenization as-cast studied alloy has obviously hardening effect that is similar to aging hardening behavior in traditional Al alloys. The precipitates are mainly Al3（Sc,Zr） and Al6Mn When homogenization temperature increases the hardness peak value is declined and the time corresponding to hardness peak value is shortened. The electrical conductivity of the alloy monotonously increases with increasing homogenization temperature and time. The decomposition of the supersaturated solid solution containing Sc and Zr which is formed during direct chilling casting and the precipitation of Al3（Sc, Zr） cause hardness increasing. The depletion of the matrix solid solubility decreases the ability of electron scattering in the alloy, resulting in the electrical conductivity increased. Tensile property result at hot rolling state shows that the optimal homogenization treatment processing is holding at 300-350℃ for 6-8 h.     

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.     

移动式钢轨焊接接头表面硬化装置及工艺的研究

介绍了所研制的移动式钢轨焊接接头表面硬化处理装置的结构、功能与使用方法.利用该装置对U71Mn和U75V钢轨焊后轨头表面硬化处理（即欠速淬火）试验.分别进行化学成分、硬度以及显微组织分析.结果表明：处理后的钢轨接头,具有较理想的显微组织和更为合适的轨顶硬度;可以成功地对钢轨焊接接头进行在线热处理,满足线路现场施工的热处理工艺要求.     

Hardness variations during aging process of deformed W-Ni-Fe ternary alloys with high nickel-to-iron ratios

The aging precipitation behavior of P phase in two kinds of alloys with 7/3 and 9/1 nickel-to-iron ratios during aging at 800℃ after deformation was studied. The results show that there are two different kinds of aging hardness variation mechanisms (the softening mechanism and the hardening mechanism) deciding the hardness variations of the alloys. When Ni/Fe is smaller than 8/2, there is only the softening mechanism which results from the decreasing of dislocation density and recovery or re-crystallization. And when Ni/Fe is greater than 8/2 besides the softening mechanism there is still the hardening mechanism that is induced by the precipitation of P phase.