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The Effect of the Parameters of Robotic TIG Welding on the Microstructure of 17-4PH Stainless Steel Welded Joint

Nalborczyk-Kazanecka Agnieszka, Mrowka-Nowotnik Grażyna

Archives of Metallurgy and Materials

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2023

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Vol. 68, iss. 1

339--344

EN

17-4PH stainless steel finds application in the aerospace industry owing to its good mechanical properties and corrosion resistance. In the literature, this steel is described as good for welding, but research shows that it may be problematic due to the formation of defects. In this study, the welded joints were made by the robotic TIG welding method with various welding speeds (2 and 3 mm/s). The joints were subjected to non-destructive testing and were free from defects. The microstructure was observed by light microscopy and scanning electron microscopy. Changes in the microstructure of the heat affected zone were observed and discussed. Based on the observation of the microstructure and the change in the hardness profile, the heat affected zone was divided into 4 characteristic regions. δ-ferrite and NbC were observed in the martensite matrix. The welded joints were subjected to heat treatment consisting of solution and aging in 550°C for 4 h. The microstructure of the heat affected zone become homogenized as a result of the heat treatment. The content of stable austenite in the welded joint after the heat treatment was about 3%.

2

The influence of aging temperature on corrosion resistance of sintered 17-4 PH stainless steel

Szewczyk-Nykiel A., Kazior J.

Inżynieria Materiałowa

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2016

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Vol. 37, nr 2

65--69

EN

Among the precipitation hardening stainless steels, martensitic grade of 17-4 PH has a special importance. This steel exhibits a good combination of high mechanical properties and good corrosion resistance. Therefore it is widely used in many branches of industry. The pitting corrosion behaviour of sintered 17-4 PH steel processed under different aging processing conditions in 0.5 M NaCl solution at 25°C was studied by open circuit potential measurement and potentiodynamic polarization technique. Compared with the sintered 17-4 PH, the corrosion resistance of the solution treated and aged steels were improved, as evidenced by a noble shift in open circuit potential, a higher pitting potential, a higher polarization resistance and a lower passive current density. Considering the influence of aging temperature on the pitting behavior of the 17-4 PH steel, it can be concluded that steel aged at 480°C exhibited the highest corrosion resistance in 0.5 M NaCl solution. While aging treatment at 500°C resulted in the worst corrosion resistance. In addition, the hardness of the solution treated and aged 17-4 PH was higher than that of the sintered steel.

PL

Zdolność do uzyskania bardzo dużej wytrzymałości bez katastrofalnych strat plastyczności, a także lepsza odporność na korozję w porównaniu ze stalą o podobnej wytrzymałości oraz niskie koszty wytwarzania czynią stal 17-4 PH bardzo atrakcyjnym materiałem dla inżynierów. W pracy dokonano oceny odporności na korozję wżerową w 0,5 M roztworze NaCl w temperaturze pokojowej spiekanej stali nierdzewnej 17-4 PH poddanej przesycaniu, a następnie starzeniu w różnych warunkach. Na podstawie przeprowadzonych badań potencjodynamicznych i wyznaczonych parametrów korozyjnych określono wpływ temperatury starzenia na odporność na korozję spiekanej stali 17-4 PH.

3

Characteristics of Products Made of 17-4PH Steel by means of 3D Printing Method

Walczak M., Gąska D., Guzik M.

Applied Computer Science

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2016

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Vol. 12, no 3

29--36

EN

The article presents the results of tests of 17-4PH steel fabricated by means of the method consisting in laser additive manufacturing (LAM) – direct metal laser sintering (DMLS). This grade of steel is characterized by excellent stress corrosion resistance in the first place and is applied as construction material in chemical, aircraft, medical or mould making industry. 3D metal printing is a relatively new method enabling significant change of structural properties of these materials at printing parameters predetermined by printers manufacturer for ”offline” printing mode. In order to achieve this goal, the authors have carried out the analysis of chemical composition, SEM tests and the tests of products surface rough-ness. Furthermore the products have been subjected to X-ray analysis by means of computed tomography (X-ray CT). Structural discontinuities have been found in upper layer and inside printouts subjected to tests.