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Influence of the nitrided layer thickness of dies made of two types of tool steel used in hot extrusion of valve forgings made of nickel–chromium steel on the durability of these tools

Hawryluk Marek, Lachowicz Marzena, Janik Marta, Ziemba Jacek, Gronostajski Zbigniew

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 4

277--293

EN

The study constitutes an analysis of the durability of dies used in the first operation of producing valve forgings from chromium–nickel steel (NCF 3015) for motor trucks. The average durability of the dies (subjected to standard thermal treatment and nitriding) in this operation equals about 800 forgings. To perform an in-depth analysis of the effect of the nitrided layer thickness (0.1 mm and 0.2 mm) and the tool material (W360 and QRO90) on the possibilities of increasing the die durability, complex studies were carried out, which included: a macroscopic analysis combined with 3D scanning, microstructural examinations using a scanning microscope and a metallographic microscope, as well as hardness measurements. A minimum of three tools were tested for different variants, and for each of them, one representative die was selected for detailed examinations. The research showed the presence of abrasive wear, thermo-mechanical fatigue and traces of adhesive wear as well as plastic deformation on the surface of the working impressions. Also observed was the effect of the extruded material sticking to the tools (high friction and the presence of intermetallic phases in the extruded material) and the forging being blocked in the smallest section of the die, which is a critical factor causing a production shutdown and the necessity of tool replacement. The highest mean durability equalling 2600 forgings was obtained for the dies with a lower carbon content and a higher content of vanadium and the nitrided layer thickness at the level of 0.2 mm. The lowest mean durability (after one forging item) was recorded for the dies made of steel with a higher carbon content and a higher chromium content, forming less stable compound carbides and the thickness layer at the level of 0.1 mm.

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Trwałość matryc zależna od kształtu wyciskanego profilu i parametrów procesu azotowania

Laurentowska-Tyczka A., Borowski J., Jurczak H.

Obróbka Plastyczna Metali

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2014

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T. 25, nr 3

215--228

PL

W pracy starano się wykazać zależność geometrii matryc, związanej z kształtem profili aluminiowych i parametrów procesu azotowania na trwałość eksploatacyjną matrycy. Matryce były poddawane jedno lub kilkukrotnemu azotowaniu gazowemu i eksploatowane do końcowego zużycia w firmie Albatros Aluminium. W artykule podjęto próbę wyjaśnienia wpływu rożnych procesów azotowania i geometrii matryc na grubość warstwy azotowanej, na trwałość matrycy. Na podstawie badań określono najbardziej optymalną grubość warstwy azotowanej w przedziale 350–400 μm. Stosowanie mniejszej grubości powoduje szybsze zużycie lub uszkodzenie matryc.

EN

This work attempted to demonstrate the dependence between die geometry, connected to the shapes of aluminium profiles and the parameters of the nitriding process, to the die's service life. Dies were subjected to single or repeated gas nitriding and used until worn out at the company Albatros Aluminium. The article undertakes an attempt to explain the influence of various nitriding processes and die geometries on the thickness of the nitrided layer and the durability of the die. Based on the research, the optimal thickness of the nitrided layer was determined to be in the range of 350–400 μm. The use of a smaller thickness causes faster wear or damage to the dies.

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Praktyczna metoda wyznaczania grubości warstwy azotowanej

Głowacki S., Majchrzak W., Majchrzak A.

Obróbka Plastyczna Metali

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2004

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T. 15, nr 2

15-25

PL

W artykule przedstawiono wyniki badań, których celem było określenie grubości warstwy azotowanej jonowo, na podstawie jednostkowego przyrostu masy (J?m) próbek - świadków obrabianych razem z wsadem. Narzędzia i próbki ze stali narzędziowej do pracy na gorąco WCL obrabiano cieplno-chemicznie w urządzeniu do azotowania jonowego JONIMP 900/500. Przedstawiono wyniki pomiarów J?m z dziesięciu procesów azotowania w temperaturze 520oC i czasie 10 h. Zmianę masy próbek mierzono za pomocą wagi analitycznej z dokładnością 10-4 g. W tablicach zestawiono wyniki pomiarów rozkładu twardości HK0,1 warstwy azotowanej badanych próbek. Podano korelację między J?m a umowną grubością warstwy azotowanej.

EN

The paper presents the results of investigation aimed at the determination of ion nitrided layer thickness on the basis of the specific mass increase (JDm) of witness samples treated together with the charge. Tools and samples of WCL hot-work tool steel have been subjected to thermochemical treatment ion the JONIMP 900/500 ion nitriding device. The results of JDmeasurements of ten nitriding processes at 520 oC for 10h have been presented. The mass increase of the samples has been measured by means of analytic scales with the accuracy of 10-4 g. The results of HK0,1 hardness distribution measurements in the nitrided layer have been assembled in tables. The correlation between JDm and the conventional nitrided layer thickness has been stated.