P_2钢的热处理工艺性和机械性能

<正> 目前国内生产的汽轮机高、中压整锻转子的材料,基本上采用P_2钢。但是通过多年的生产实践,各方面对这种钢作出了不同的评价,力图研制出新钢种来代替P_2钢。为了给研究新钢种的人们提供一些参考资料,特将苏联对P_2钢的热处理工艺性和机械性能的研究资料摘编于下。     

超细硬质合金WC-8Co-0.8(Cr_3C_2/TaC)的组织与性能

以超细WC-8Co硬质合金为研究对象,混合添加晶粒长大抑制剂Cr3C2/TaC。结果表明,合金在添加0.8wt%Cr3C2/TaC时的TRS达到3675MPa,而在添加0.5wt%和1.0wt%Cr3C2/TaC时的TRS降到2120MPa;Cr3C2/TaC在很大程度上影响了合金烧结时的致密化,WC-8Co-0.8wt%(Cr3C2/TaC)压坯在1400℃下完全致密化需要的烧结时间为60分钟;而同类普通WC-8Co-0.8wt%(Cr3C2/TaC)的压坯,由于没有超细粉末的高表面能,烧结60分钟后密度只能达到理论密度的98.8%;TaC和Cr3C2对W在γ相中的固溶度具有相反的作用。     

Preparation for femur prosthesis of ceramic-metal combination artificial hip joint

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稀土对上引连铸铜管坯质量影响的研究

通过上引连铸实验、力学性能检测和金相观察，研究了上引连铸中加入稀土添加剂对铜管坯机械性能的影响。研究结果表明，添加1^#稀土的铜管坯抗拉强度平均提高6．03％，延伸率平均提高10．37％；添加2^#稀土的铜管坯抗托强度平均提高3．03％，延伸率平均提高12．94％。且实验结果确认了稀土在上引连铸生产铜管中的有利作用。     

Rheologic behavior and PIM processing of WC-TiC-Co powder feedstock

An improved wax-based binder was developed for the powder injection molding (PIM) of WC-TiC-Co cemented carbides. The critical powder loading and the rheologic behavior of the feedstock were determined. It was found that the critical powder loading could achieve up to 62.5% (volume fraction) and the feedstock exhibited a pseudo-plastic flow behavior. The injection molding, debinding and sintering processes were studied. The dimension deviation of the sintered samples could be controlled in the range of ±0.2% with the optimized processing parameters and the mechanical properties were better than or equivalent to those of the same alloy made by conventional press-sintering process.     

EFFECT OF TOOL WEAR ON MICROSTRUCTURE, MECHANICAL PROPERTIES AND ACOUSTIC EMISSION OF FRICTION STIR WELDED 6061 Al ALLOY

Tool condition is one of the main concerns in friction stir welding （FSW）, because the geometrical condition of the tool pin including size and shape is strongly connected to the microstrueture and mechanical performance of the weld. Tool wear occurs during FSW, especially for welding metal matrix composites with large amounts of abrasive particles, and high melting point materials, which significantly expedite tool wear and deteriorate the mechanical performance of welds. Tools with different pin-wear levels are used to weld 6061 Al alloy, while acoustic emission （AE） sensing, metallographic sectioning, and tensile testing are employed to evaluate the weld quality in various tool wear conditions. Structural characterization shows that the tool wear interferes with the weld quality and accounts for the formation of voids in the nugget zone. Tensile test analysis of samples verifies that both the ultimate tensile strength and the yield strength are adversely affected by the formation of voids in the nugget due to the tool wear. The failure location during tensile test clearly depends on the state of the tool wear, which led to the analysis of the relationships between the structure of the nugget and tool wear. AE signatures recorded during welding reveal that the AE hits concentrate on the higher amplitudes with increasing tool wear. The results show that the AE sensing provides a potentially effective method for the on-line manitoring of tool wear.     

WC/TiC粒径比对WC-TiC-Co硬质合金的显微结构和机械性能的影响

<正>为提高硬质合金的机械性能,人们一直尝试细化碳化物,因此,有报道称超细纳米晶的WC-Co硬质合金具有更高的硬度和耐磨性。但是,硬质合金的细化还没有在WC-TiC-Co合金中得到应用,后者比WC-Co硬质合金更广泛地用于切削工具。     

Fe72B22Y6块体非晶合金在600～700℃空气中的氧化行为

铁基块体非晶合金由于具有优良的软磁性能和机械性能，是微电子铁心和软磁管件用的最佳材料。为了在较高温度下使用铁基非晶合金，了解合金在高温下的氧化行为是非常重要的。因此，研究了Fe-B-Y三元非晶合金的氧化行为，特别是非晶组织在其氧化机理中的作用。研究用的铁基非晶合金Fe72B22Y6（原子百分数）是由压铸法制得，并用电弧熔炼法制备同成分的晶态合金以供对比研究。非晶态合金试样直径为1mm、长10mm，晶态试样剪切成矩形（5×5×2．5mm^3），随后均用金刚石研磨膏加以研磨。     

The eta phases and mechanical properties of TIG welded joints of WC-Co cemented carbide and steel

The tungsten-inert-gas (TIG) arc welding experiments of cemented carbide YG30 and steel 45 were carried out using the Ni-Fe-C filling alloys. The eta phases and mechanical properties of welded joints were analyzed by means of scanning electronic microscope (SEM) , transmission electronic microscope (TEM) coupled with selected diffraction, electronic probe microanalysis and bending strength method. The experimental results show that the chemical composition of the filling alloys affects eta phase formation. When the carbon and nickel contents in filling alloys are O. 61 wt% and 55. 29 wt% ,respectively, no eta phases form. And the joint bending strength is the highest to 1. 352 GPa. But if they are O. 01wt% and 55.38wt%, the eta phases are formed at the boundaries of the cemented carbide and the weld, and the thickness of eta phase layer is about 110 micrometers. And the joint bending strength is low. Usually, these eta phases are anomalously granular,and easy to accumulate at the boundaries between cemented carbides and the weld. They are multiple M6C rich in tungsten and iron.     

微量元素锑对不同断面球铁的影响

通过在稀土镁球铁中加入微量元素锑,能有效地获得铸态珠光体球铁,较明显的提高了材料的综合机械性能。同时在不同断面的球铁中,对于稳定珠光体,提高石墨球化等级也起到有益的作用。