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本文采用激光选区熔化成形(Selective Laser Melting,SLM)技术制备了高温合金GH4169复杂结构件.研究了不同成形方法和不同成形工艺条件对构件的影响,并对构件力学性能、成形尺寸、成形周期、表面粗糙度进行表征.结果表明:选择倾斜45°角生长时,构件在生长过程中的应力较小,未出现应力开裂的现象且表面缺陷减少;光斑补偿值0.06 mm效果最佳,样件表面较光滑,基本无凹凸缺陷;在光斑补偿值0.06mm、零件倾斜45°生长的GH4169合金复杂构件,其样件的力学强度、延展性能明显优于铸件,并且尺寸精度高、成形周期短、粉末利用率高,表面粗糙度较低(Ra≤1.6 μm).  相似文献
2.
利用自主研发的DiMetal-100型激光选区熔化设备制备与基板平面成不同倾斜角的Ti6Al4V非标准拉伸试样,研究熔化成形后合金的显微组织、物理和力学性能。结果表明,Ti6Al4V合金粉末熔化成形后的组织为针状α′马氏体和(α+β)相,随倾斜角度变化,试样中α/α′相与β相的相对含量也发生变化,倾斜角为45°试样中β相含量最高;α′马氏体呈柱状分布于(α+β)相中,并且方向始终平行于成形方向(Z轴方向)。随SLM成形试样的倾斜角从0°增加到90°,其相对密度先减小后增大,并在90°时达到最大值96.1%;试样的硬度和抗拉强度均先升高后降低,在45°时达到最大值,硬度为393 HV,抗拉强度为1288 MPa;试样表面粗糙度Ra也呈先增大后减小的趋势,在0°时达到最小值8.77μm,在30°时达到最大值19.55μm。  相似文献
3.
Additive manufacturing (AM) & 3D printing can realise rapid delivery of high-quality and complex-geometry industrial product like steel mould with conformal cooling channels. In this paper, selective laser melting (SLM), a typical AM technique, was used to investigate the processing of P20 tool steel which is commonly used for plastic mould. SLM processing parameters, including scanning speed and laser power, were investigated to produce test specimens with high density. High cooling rate induced formation of refined dendrite and major crystalline phases in the as-printed P20 are identified largely as martensite, with an additional small portion of retained austenite. A subsequent tempering heat treatment has been done to eliminate these metastable phases and guarantee overall structural stability and mechanical property of the as-printed P20. Hardness at 250°C and corrosion resistance in 3.5 wt-% NaCl aqueous solutions were measured to evaluate the reliability of P20 mould steel under service, which show rather satisfactory results.  相似文献
4.
Spherical 24CrNiMo alloy steel powder used for selective laser melting (SLM) fabricating high-speed train brake disc was prepared by the vacuum induction melting gas atomisation (VIGA) method. Powder morphology, particle size, flowability and microstructure were measured. Part properties fabricated by SLM were investigated via some modern analysis method. The experimental results showed that powder mean particle size D50 was 75 μm, flowability was 16.69 s/50 g and apparent density was 4.71 g cm−3. 24CrNiMo alloy steel specimen microstructures prepared by SLM consisted of proeutectoid ferrite and granular bainite. Average microhardness was 346 HV, tensile strength was 1223 MPa, extensibility was 13.1% and the product of strength and elongation was 16.1 GPa%. 24CrNiMo alloy steel powder prepared by the VIGA method had good laser printability and huge potential application value for SLM-fabricated brake disc.  相似文献
5.
A high oxygen content can lead to metallurgical defects such as holes and microcracks in the products of selective laser melting (SLM) that significantly reduce the density and mechanical properties of a denture. In this study, a batch of a Co–Cr alloy powder was subjected to forced oxidation. SLM was used to prepare specimens from the powder before and after the treatment for the performance tests. The results showed that Co–Cr alloy powders with oxygen contents 184 and 616 ppm could both achieve good shaping of the specimens under identical SLM conditions. There was no significant difference between the specimens in terms of fuselage morphology, microstructure, density, tensile strength, yield strength and hardness. However, the elongation of the alloy synthesised using the higher oxygen content powder was significantly lowered, but still higher than that required by the ASTM F75 Casting Standard of the United States.  相似文献
6.
In powder bed fusion additive processes the flow properties of the powder influence the quality of the final component and the efficiency of the process. In this investigation an attempt is made to identify flowability indicators which can describe the flow performance of the powder during the powder layering (i.e. recoating) step; common to all powder bed fusion processes. To this end, shear tests were performed by means of a powder rheometer. Bulk density, flow function and degree of cohesion were measured. The results suggest that there is a good correlation between the aforementioned parameters and the flowability of the powder during SLM processing. In addition, it was found that thermal treatments and tumbling enhance flowability. Thermal treatments were performed at 150, 200 and 250°C for a period of 10 min and in air.  相似文献
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激光选区熔化技术是增材制造技术的一种,该技术自诞生以来在金属样件制备过程中发挥越来越重要的作用。但是运用该技术制备成型件的组织研究尚未明确,本文以GH3625高温合金为例,研究选区激光熔化成型件组织特点及拉伸性能。结果表明,选区激光熔化成型件组织主要为胞状晶,选区激光熔化微熔池中,晶粒生长方向在同一个区域中呈现出典型的细小柱状晶(亚晶)和近似六边形的胞状晶。拉伸实验结果表明选区激光熔化成型试样具有良好的拉伸性能。  相似文献
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