Comparative study of the microstructure between a laser beam melted 17-4PH stainless steel and its conventional counterpart

High-Resolution Microstructure Characterization of Additively Manufactured X5CrNiCuNb17-4 Maraging Steel during Ex and In Situ Thermal Treatment

“…The measured Vicker hardness of the additively manufactured sample lies between 360 and 380 HV1, which is in line with other data presented in the literature. However, recent data [25] show that the ductility is lower than for samples prepared by conventional metallurgy, and this can probably also be attributed to the presence of the oxides and carbides. Further, the heterogenous distribution of the elements that segregate at the melt-pool boundaries can also be responsible for crack initiation.…”

Susceptibility to Pitting and Environmentally Assisted Cracking of 17-4PH Martensitic Stainless Steel Produced by Laser Beam Melting

“…Recently, there have been many studies in the literature on the microstructures of precipitation-hardening stainless steels generated by additive manufacturing (AM) processes, and in particular laser melting processes [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. Most of the studies have highlighted differences in the austenite to martensite ratio in additive manufactured steels as compared with their conventional counterparts [ 9 , 10 , 11 , 12 , 13 , 14 ], in agreement with previous works showing variations of this ratio in a very large range up to 100% [ 15 , 16 , 17 , 18 , 19 ]. The results showed that the austenite to martensite ratio strongly depended on the chemical composition and microstructure of the powder used, as well as on the nature of the vector gas used during the AM process [ 15 , 19 , 20 , 21 ].…”

“…The results showed that the austenite to martensite ratio strongly depended on the chemical composition and microstructure of the powder used, as well as on the nature of the vector gas used during the AM process [ 15 , 19 , 20 , 21 ]. In particular, we have shown, in a previous work, that the microstructure of L-PBF 17-4PH MSS in the H900 metallurgical state (annealing at 1040 °C for 30 min, air-quench, ageing treatment at 482 °C for 1 h) was mainly martensitic, but with a non-negligible austenite content of about 13%, whereas the conventional counterpart only contained less than 1% austenite [ 13 ]. Here, it was interesting to note that post-building heat treatments, for example, H900, homogenised the microstructure (elimination of the dendritic solidification structure and crystallographic texture), whereas as-built parts were characterised by strong anisotropy in grain morphology and texture [ 14 , 16 , 17 , 18 ].…”

“…The detrimental effect of residual stresses has also been shown during crack propagation tests on single edge-notched tension samples [ 26 ]. However, in a previous work, we showed that H900 heat treatment could efficiently release residual stresses [ 13 ]. Then, another issue of AM processes was the presence of gas pores and lack-of-fusion pores that depended on process parameters, but also powder choice, and could influence the corrosion resistance [ 16 , 18 , 27 , 28 , 29 , 30 ].…”

Enhancing tensile and fatigue properties of additively manufactured alloys by post-processing heat treatment

“…On the other hand, the excellent weldability of the 17-4 PH alloy makes it amenable to AM using techniques such as the LB-PBF [246][247][248][249][250][251][252] and DED [253][254][255][256]. Majority of the work reported hitherto has been on the process -microstructure -property relationships in the 17-4 PH steel fabricated by LB-PBF [247,[257][258][259]. However, microstructural-and hence mechanical property-anisotropy is a predominant issue in alloys manufactured using LB-PBF [260,261].…”