Revistas
Autores:
Vilanova, M. (Autor de correspondencia); Garciandia, F.; Sáinz, Shandra; et al.
Revista:
JOURNAL OF MATERIALS PROCESSING TECHNOLOGY
ISSN:
0924-0136
Año:
2022
Vol.:
300
Págs.:
117398
Inconel 738LC (IN738LC) is a nickel-based superalloy specially used in the hot section components of turbine engines due to its outstanding hot corrosion resistance and mechanical properties under high temperatures. However, one of the main drawbacks of this superalloy is its susceptibility to cracking when it is manufactured by Laser Powder Bed Fusion (LPBF). This paper describes the effect of 400 W laser power and 90 degrees rotation strategy on the formation of cracks and the capability of Hot Isostatic Pressing (HIP) post-treatment to substantially reduce them in the LPBF manufactured IN738LC samples. Based on the characterization of the cracks, the most important finding from this research work was the identification of the limit of crack width at 6 mu m, beyond which the HIP treatment is unable to effect crack healing. Furthermore, this research shows that the HIP treatment leads to microstructural changes in the IN738LC samples with a massive precipitation of gamma ' phase. Indeed, the formation of precipitates implied an increase in the microhardness of up to 23 %, which demonstrates that the HIP treatment also affects the mechanical properties of the IN738LC superalloy. It was therefore shown that the HIP treatment could be a crucial process to substantially reduce the defects of the additively manufactured parts.
Revista:
POWDER METALLURGY
ISSN:
0032-5899
Año:
2020
Vol.:
63
N°:
2
Págs.:
75 - 79
Thermochemical treatments like plasma nitriding or surface carburizing are commonly used to enhance surface hardness of steel components. An important difference between these treatments is the temperature at which they are carried out. In the present paper, the surface carburizing was carried out following a recently reported non-isothermal low pressure carburizing (LPC) treatment. In order to gain a comparative view of the effect of different treatments on the microstructure, microhardness, fatigue and impact properties, materials with distinct hardenability and widely used in the industrial production were evaluated. Tests were also carried out using industrially processed components aimed to an application demanding high wear resistance. The microstructural evolution during case hardening was studied by optical and electron microscopy.
Revista:
METAL ADDITIVE MANUFACTURING
ISSN:
2057-3014
Año:
2017
Vol.:
3
N°:
1
Págs.:
112 - 115
Revista:
INTERNATIONAL JOURNAL OF POWDER METALLURGY
ISSN:
0888-7462
Año:
2016
Vol.:
52
N°:
2
Págs.:
47 - 55
Despite the high oxygen sensitivity of manganese, its attractiveness as an alloying element in powder metallurgy steels is mainly cost but also accompanied with performance. Manganese is still scarcely used in industry, but research over many years has led to the development of manganese steels as lean alternatives for nickel- and copper-steels. Based on adding manganese in prealloyed form, or through a specially designed master alloy, the differences in microstructure, tensile strength, and hardness after sintering are discussed in terms of the overall chemical composition and alloying method. A detailed study of microstructural evolution is presented, based on interrupted sintering experiments from temperatures associated with the changes observed in the corresponding dilatometry traces.
Revista:
POWDER METALLURGY
ISSN:
0032-5899
Año:
2015
Vol.:
58
N°:
5
Págs.:
328 - 334
Powder blends within the Fe-Cu-C system are extensively used by the Powder Metallurgy industry. Based on the optimisation of mechanical properties the purpose of this work is to further understand the dimensional changes produced in the powder compact during sintering. Green compacts containing copper and carbon within ranges 0.5-3.5% Cu and 0.3-0.9% C were die pressed and sintered under different conditions varying processing parameters, including compaction pressure, temperature and time. Better understanding of the effect of different Cu/C combinations on dimensional changes was approached using the results obtained from dilatometry studies combined with interrupted sintering experiments. For selected specimens the effect of elemental Ni additions, at 1 and 4%, on dimensional changes was studied along with a detailed description of microstructural development. It was clearly observed that swelling due to copper melting and grain boundary diffusion is diminished as graphite additions were increased. The impact of Cu-C-Ni additions on hardness was also evaluated.
Autores:
Bueno, S.; Saccarola, S.; Karuppannagounder, A.; et al.
Revista:
POWDER METALLURGY
ISSN:
0032-5899
Año:
2012
Vol.:
55
N°:
2
Págs.:
92 - 94
Ecological and economic demands are driving PM markets to incorporate less expensive, yet effective, alloying elements in iron based powders. To investigate their potential for this purpose recently developed sinter-hardening iron powders containing Cr and smaller amounts of Mo and Ni were industrially sintered at 1120 and at 1240 degrees C under laboratory conditions. One set of samples, containing 0.8% graphite additions, was cooled so to obtain sinter-hardened steels. A second set of samples, containing 0.3% graphite, was cooled under normal conditions and subjected to a secondary carburising treatment. The microstructures and mechanical properties developed were compared.
Autores:
Saccarola, S.; Belin, G.; Bueno, S.; et al.
Revista:
POWDER METALLURGY
ISSN:
0032-5899
Año:
2010
Vol.:
53
N°:
3
Págs.:
184 - 187
A group of high strength, cost effective PM steels has been generated by combining alloying elements (e. g. Cr, Mo, Ni, Cu, Mn) in predetermined concentrations. The main aim was to optimise the balance between compressibility, hardenability and properties. Special efforts were devoted to identifying compositions and processing conditions giving specific proportions of transformation products (martensite, bainite, etc.) in an attempt to correlate microstructural characteristics with the mechanical properties of the sintered steels after tempering. Measuring dimensional changes after sintering as well as properties such as yield stress and hardness allowed processing conditions to be optimised for the composition and characteristics of the powder mixture.