MICROSTRUCTURE CHARACTERIZATION AND STRENGTH ASSESSMENT OF A HEAT-TREATED SELECTIVE LASER MELTED 300-GRADE MARAGING STEEL

Author(s):  
Fabio Conde ◽  
Waldek Wladimir Bose Filho ◽  
Julian Escobar ◽  
André Tschiptschin ◽  
André Jardini ◽  
...  
Author(s):  
I. Neuman ◽  
S.F. Dirnfeld ◽  
I. Minkoff

Experimental work on the spot welding of Maraging Steels revealed a surprisingly low level of strength - both in the as welded and in aged conditions. This appeared unusual since in the welding of these materials by other welding processes (TIG,MIG) the strength level is almost that of the base material. The maraging steel C250 investigated had the composition: 18wt%Ni, 8wt%Co, 5wt%Mo and additions of Al and Ti. It has a nominal tensile strength of 250 KSI. The heat treated structure of maraging steel is lath martensite the final high strength is reached by aging treatment at 485°C for 3-4 hours. During the aging process precipitation takes place of Ni3Mo and Ni3Ti and an ordered solid solution containing Co is formed.Three types of spot welding cycles were investigated: multi-pulse current cycle, bi-pulse cycle and single pulsle cycle. TIG welded samples were also tested for comparison.The microstructure investigations were carried out by SEM and EDS as well as by fractography. For multicycle spot welded maraging C250 (without aging), the dendrites start from the fusion line towards the nugget centre with an epitaxial growth region of various widths, as seen in Figure 1.


2021 ◽  
pp. 109399
Author(s):  
Zhiping Sun ◽  
Wenqing Wu ◽  
Yongnan Chen ◽  
Zhanwei Yuan ◽  
Yongshuai Zhang ◽  
...  

2020 ◽  
Vol 405 ◽  
pp. 133-138
Author(s):  
Ludmila Kučerová ◽  
Andrea Jandová ◽  
Ivana Zetková

Maraging steel is an iron-nickel steel alloy, which achieves very good material properties like high toughness, hardness, good weldability, high strength and dimensional stability during heat treatment. In this work, maraging steel 18Ni-300 was manufactured by selective laser melting. It is a method of additive manufacturing (AM) technology, which produces prototypes and functional parts. Sample of additively manufactured and conventional steel with the same chemical composition were tested after in three different states – heat treated (as-built/as-received), solution annealed and precipitation hardened. Resulting microstructures were analysed by light and scanning electron microscopy and mechanical properties were obtained by hardness measurement and tensile test. Cellular martensitic microstructures were observed in additively manufactured samples and conventional maraging steel consisted of lath martensitic microstructures. Very similar mechanical properties were obtained for both steels after the application of the same heat treatment. Ultimate tensile strengths reached 839 – 900 MPa for samples without heat treatment and heat treated by solution annealing, the samples after precipitation hardening had tensile strengths of 1577 – 1711 MPa.


2007 ◽  
Vol 537-538 ◽  
pp. 647-654 ◽  
Author(s):  
Janez Grum ◽  
Janez Marko Slabe

The paper describes the results obtained in an investigation of laser remelting of specimens made of 12% Ni maraging steel suitable for the manufacture of highly thermomechanically loaded machine parts or tool parts. The aim of the investigation was to establish the state of differently heat treated maraging steel after a laser repair processes including melting of the material. An analysis of the specimens with an optical microscope after laser remelting showed, regardless of the initial condition, a cellular-dendritic microstructure in the remelted track. In the heat-affected zone surrounding the laser-remelted track the microstructure varied considerably also regardless of the initial condition. A microstructure analysis supported by microhardness measurements made it possible to define several microstructural zones or sub-zones in the heataffected zone. The measurement of residual stresses using the relaxation hole-drilling method close to the laser-remelted track was used to study the influence of the initial material state on the residual stresses after laser remelting.


2019 ◽  
Vol 785 ◽  
pp. 499-511 ◽  
Author(s):  
Chaoyue Chen ◽  
Yingchun Xie ◽  
Xincheng Yan ◽  
Renzhong Huang ◽  
Min Kuang ◽  
...  

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 218 ◽  
Author(s):  
Troy Y. Ansell ◽  
Joshua P. Ricks ◽  
Chanman Park ◽  
Chris S. Tipper ◽  
Claudia C. Luhrs

Changes in the mechanical properties of selective laser melted maraging steel 300 induced by exposure to a simulated marine environment were investigated. Maraging steel samples were printed in three orientations: vertical (V), 45° (45), and horizontal (H) relative to the print bed. These were tested as-printed or after heat-treatment (490 °C, 600 °C, or 900 °C). One set of specimens were exposed in a salt spray chamber for 500 h and then compared to unexposed samples. Environmental attack induced changes in the microstructural features and composition were analyzed by scanning electron microscopy and energy dispersive spectroscopy respectively. Samples printed in the H and 45° directions exhibited higher tensile strength than those printed in the V direction. Corrosion induced reduction in strength and hardness was more severe in specimens heat-treated between 480 °C and 600 °C versus as-printed samples. The greatest decrease in tensile strength was observed for the 45°-printed heat-treated samples after exposure. A comparison between additive and subtractive manufactured maraging steel is presented.


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