High-Nitrogen Cr-Mo Steels for Corrosion Resistant Bearings

Berns, Hans; Trojahn, W.

doi:10.1520/stp24831s

Cited by 16 publications

(8 citation statements)

References 1 publication

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“…5.2a) II (Berns and Trojahn 1993) grade down to lOh and all bearings had failed after 80 h but none of the HNS rings after 240 h (Fig. The PESR process does not only provide a sufficient nitrogen content, but also reduces the size and frequency of non-metallic inclusions like in ordinary ESR.…”

Section: Hard Stainless Steelsmentioning

confidence: 95%

High Nitrogen Steels

Gavriljuk¹,

Berns²

1999

Engineering Materials

385

110

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The use of general descriptive names, registered names, trademarks, ete. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.Typesetting: Camera-ready eopies from authors Cover-Design: MEDIO, Berlin Printed on acid-free paper SPIN 10730039 6213020 5 4 3 2 1 0 to BELA and ISOLDE PrefaceDuring the second half of this century the nitrogen concentration of steel moved in both directions: down in constructional grades by oxygen blowing to prevent brittle fracture upon age hardening at ambient temperature and up in stainless grades to improve strength, corrosion resistance and austenite stability. The gradual recognition of the beneficial effects of this element on the properties of high alloy steels led to a widespread development of high nitrogen steels (HNS) documented by numerous applications and the proceedings of five HNS conferences at LilIe (France) 1988, Aachen (Germany) 1990, Kiev (Ukraine) 1993, Kyoto (Japan) 1996 and HelsinkilStockholm (FinnlandISweden) 1998. The word "high" in HNS is not clearly defined but accounts e.g. for 0.1 mass% of nitrogen in creep resistant steels, 0.9 mass% in stainless grades or 2 mass% in tool steels. "High" best refers to "intentionally raised" by appropriate alloying or by pressure and powder metallurgy. For convenience steel grades are designated by their approximate content of alloying elements in mass% omitting unintentional minor additons of Si, Mn, C, P, S asf. As an example Cr22Ni5M03NO.2 stands for a stainless duplex grade.The present book starts by comparing the effects of nitrogen and carbon on the atomic structure and interaction within the crystallattice. Next the constitution of HNS is investigated leading to specific microstructural features. Based on this background the mechanisms behind the mechanical, chemical and tribological properties of HNS are derived. This concludes the fundamentals treated in chapters one to three. Chapter four comes down to shop practice of manufacturing HNS which, in respect to e.g. melting, hot working, and welding, may be quite different from respective carbon grades. In chapter five, different HNS for special applications are presented like e.g. hardenable steels for stainless bearings, high strength austenitic steels for non-magnetic retaining rings, superaustenitic stainless sheet for the chemical industry or solution nitrided impellers for pumps. Chapter six is an attempt to summarize key aspects of HNS.The book is meant for material scientist working in the field of high alloy steels and also for engineers engaged in materials technology, material selection and design. The work covers a wide scope from the atomic structure to the application of HNS and was written by a metal physicist and an engineer.

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Section: Hard Stainless Steelsmentioning

confidence: 95%

High Nitrogen Steels

Gavriljuk¹,

Berns²

1999

Engineering Materials

385

110

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“…A rough classification of the primary carbides after their diameters in the transverse section was performed using 11 light optical micrographs at magnification 200x (Fig. 4), since the large carbides may act as defects in fatigue crack initiation [2,4,7]. Results are shown in Table 2.…”

Section: Steel Aisi Symbolmentioning

confidence: 99%

“…Early works on the fatigue fracture of AISI D2 type cold work tool steel have been performed by Berns et al [2]. In rotating bending and compact tension tests those authors reported that fatigue cracks definitely initiated at the edges of primary chromium carbides at the carbide-matrix interface in case of tempering at temperatures below 200 C. After tempering at higher temperatures the primary carbides were fractured themselves, thus nucleating fatigue cracks.…”

Section: Introductionmentioning

confidence: 99%

Influence of surface residual stresses on gigacycle fatigue response of high chromium cold work tool steel

Sohar¹,

Betzwar-Kotas

Gierl

et al. 2008

Materialwissenschaft Werkst

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The effect of surface compressive residual stresses (RS) induced by surface grinding and polishing on the gigacycle fatigue behavior of medium-carbon high-chromium alloy cold work tool steel was evaluated. Two test series were performed: Specimens of series I revealed high compressive RS of about -800 MPa at the surface, resulting from grinding with fine emery paper, which treatment had definitely a beneficial influence on the fatigue endurance strength. The existence of surface RS was also revealed to be responsible for the location of the fatigue crack initiation. High compressive RS favored internal crack origins. In this case crack nucleation sites were primary carbide clusters in the interior of the specimen, forming so-called fish-eyes at the fracture surface. In contrast, specimens of test series II had only very low RS, which enabled crack initiation near/at the surface at primary carbides/clusters. Furthermore, it has been shown that the high initial RS are prone to partial relaxation through cyclic loading for which the mechanisms are currently unknown. In this case near-surface induced failure was obtained. It was possible to confirm the experimentally obtained data by the use of the concept of local fatigue strength as function of effective RS. The relaxation of high initial RS was experimentally confirmed through RS measurements at runout specimens (10 10 cycles without failure

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“…The combined research effort of Universities, steel, bearing and turbine engine manufacturers over the past 8 years has led to the introduction of a new nitrogen alloyed martensitic stainless steel, Cronidur 30, for rolling bearing and ball screw applications used in demanding applications such as turbine engines, cryogenic rocket turbopumps [1], helicopters, space machanics and aircraft structural components [2]. This new class of bearing steel has demonstrated a 100 times improved corrosion resistance over AISI 440C and a 5 times improvement in bearing life over M50 steel.…”

Section: Introductionmentioning

confidence: 99%

Progress in Bearing Performance of Advanced Nitrogen Alloyed Stainless Steel, Cronidur 30

Trojahn¹,

Streit²,

Chin³

et al. 1999

Mat.-wiss. u. Werkstofftech.

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The bearing rig tests performed in this study, demonstrate superior bearing performance of Cronidur 30 steel over conventional bearing steels. In these tests the L10 life of Cronidur 30 steel as calculated by the DIN/ISO 281 method was 80 times the unfactored L10 life under full lubrication conditions. In boundary lubrication conditions, the Cronidur 30 steel demonstrated the L10 life capability typical of EHD lubrication conditions, whereas the other steels showed a drastically reduced lives. In tests with predamaged races and boundary lubrication conditions, Cronidur 30 demonstrated 8 times the calculated L10 life, whereas the conventional steels exhibited further debit in lives as compared to the boundary lubrication testing whithout predamage. The improved performance of Cronidur 30 steel over conventional bearing steels is attributed to its unique compositional formulation and microstructure that results in provision of balanced properties in the alloy – hardness, toughness and corrosion resistance.

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High-Nitrogen Cr-Mo Steels for Corrosion Resistant Bearings

Cited by 16 publications

References 1 publication

High Nitrogen Steels

High Nitrogen Steels

Influence of surface residual stresses on gigacycle fatigue response of high chromium cold work tool steel

Progress in Bearing Performance of Advanced Nitrogen Alloyed Stainless Steel, Cronidur 30

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