Effect of processing parameters on the fractions of martensite in 17-4 PH stainless steel fabricated by selective laser melting

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

“…For the 17-4PH AM samples, the fewer and finer NbC particles as compared with the CM samples constituted a positive microstructural feature in terms of susceptibility to pit initiation, and then to EAC. However, the L-PBF process could also lead, which was the case with the experimental conditions fixed here, to a significantly higher amount of reversed austenite as compared with the conventional metallurgy [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. The results showed that the high austenite amount was associated with a higher pit propagation rate ( Figure 5 and Table 3 ), leading to significantly different pit shape factors ( Table 3 ), as well as more intense metastable pits with a longer lifetime ( Figure 4 and Table 2 ) for the AM samples as compared with the CM samples.…”

“…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 ].…”

Surface finish, microhardness and microstructure of laser metal deposited 17-4PH stainless steel

“…[8][9][10] Several studies have been conducted to characterise the effect of processing conditions, powder characteristics and heat treatment on the evolving or resultant properties of this stainless steel alloy. [11][12][13][14][15][16][17][18][19][20][21][22][23][24] Most of the available studies are mostly focused on laser powder bed fusion technology. Thus, there is limited literature on the laser metal deposited 17-4PH.…”

Crystallographic aspects of 17–4 PH martensitic steel produced by laser-powder bed fusion

“…Moreover, the phase composition also depends on LPBF variables. In particular, an increment in the laser energy density increases the volume fraction of the martensitic phase, while a reduction in the spacing between the successive laser scans (i.e., the hatch distance) promotes the austenite formation [18]. Furthermore, the phase fraction may also be influenced by the orientation of the building direction and the strategy of the laser scans [19].…”