High-nickel Steel Research Articles

The Influence of Laser and Eelctric Heating of High Nickel Steel on the Martensitic Transformation Characteristics

The Influence of Laser and Eelctric Heating of High Nickel Steel on the Martensitic Transformation Characteristics

高ニッケル耐熱鋼‐低合金鋼ＳＵＨ３５異種摩擦圧接材の高温低サイクル疲労

This paper describes the high temperature low cycle fatigue life of high nickel steel (HNIS)-SUH35 friction welded specimens. High temperature low cycle fatigue tests were carried out on HNIS, SUH35 base metal specimens and HNIS-SUH35 friction welded specimens. HINS base metal specimens had superior fatigue strength in comparison with SUH35 specimens. The fatigue life of the welded specimens was equivalent to that of SUH35 specimens. The fracture point of the welded specimens was at SUH35 steel, 2 [approx] 3 mm apart from the weld interface. The fatigue life of the welded specimens was estimated from the strain concentration calculated in the finite element analysis. The fracture point of the welded specimen was well explained by the Mises' equivalent strain concentration at SUH35 steel. The low cycle fatigue life of a welded specimen was predicted from the total strain range obtained in the finite element analysis. The predicted low cycle fatigue life was three times smaller than that in the experiments. The difference between the predicted and experimental fatigue lives was attributed to the compressive mean stress occurring in SUH35 steel. The life prediction using the parameter which took account of the tensile stress amplitude successfully predicted the low cycle fatigue life of the welded specimen. (author).

Changing of the Crystalline Structure of Martensite of High-Nickel Steel at Low Temperature

Changing of the Crystalline Structure of Martensite of High-Nickel Steel at Low Temperature

Effects of phase hardening on martensite transformations in high-nickel steel

In the present work we studied the conditions of developing the processes of austenite recyrstallisation and the changes of crystalline structure of martensite formed in the reversed γ-phase

高Cr高Ni鋼の高温クリープにおいて形成される転位下部組織に及ぼす固溶元素の効果

高Cr高Ni鋼の高温クリープにおいて形成される転位下部組織に及ぼす固溶元素の効果

Effect of chromium and nickel on the structure formation over the section of large forgings of Cr-Ni-Mo steels

1. The dependences of the stability of supercooled austenite in continuous cooling in the temperature range of the pearlitic and bainitic transformations on the chromium and nickel content of the investigated steels are of a nonlinear nature with concentrational intervals of the strongest influence. 2. By computerized modeling we calculated the structural and temperature fields forming over the section of large forgings during quenching in oil, and the results of the calculation were generalized in the form of structural diagrams of the influence of chromium and nickel. 3. By varying the chromium and nickel content, structures of the same type can be obtained in forgings with specified diameter. The use of the presented structural diagrams provides for rational choice of material for forgings serving important purposes. 4. According to the data of the structural diagrams, chrome-nickel-molybdenum steels with 2% Cr and up to 1% Ni may be recommended as substitutes for high nickel steels for forgings with up to 800 mm diameter.

Shape Memory Effect in High Nickel Steels

Shape Memory Effect in High Nickel Steels

Use of economically alloyed and nickel-free steels in polymer-production equipment

The widespread use of economically alloyed steels 08KH22N6T, 08KH21N6M2T, 08KH18G8N2T, 07KH13AG20, and 08KH12 in newly developed equipment in place of the currently used high-nickel steels 12KH18N10T and 10KH17N13M2T has brought about a significant reduction in the net cost and metal consumption of production equipment in petrochemical plants as well as a savings in acutely deficient nickel. The authors review and test the corrosion properties of these new steels in a variety of polymers including polyethylene, polypropylene, polyvinyl butyryl, and propylene oxide combined with styrene, and make specific recommendations on where, throughout the plant and process, each of these steels should be utilized.

CRONIFER 2328

Abstract CRONIFER 2328 is a titanium-stabilized, high-chromium and high-nickel austenitic stainless steel with additions of molybdenum and copper. It exhibits good corrosion resistance against sulfuric and phosphoric acids. Also, it has good resistance against pitting and stress-corrosion cracking. Cronifer 2328 is used widely in the chemical industry for equipment and for the storage and transportation of various acids and solutions. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: SS-411. Producer or source: Vereingte Deutsche Metallwerke AG.

STRUCTURE PECULIARITIES OF MARTENSITE, FORMED BY THE EFFECT OF MAGNETIC FIELD

Structural changes in alpha-martensite forming by the action of a magnetic field have been investigated for high-nickel steel which remains in an austenitic state even when subjected to very low temperatures. It is shown that the thin plate martensite produced by exposure to a pulsed magnetic field becomes lenticular in the course of subsequent isothermal soaking without application of a magnetic field. Electron microscope studies of the structure of martensite plates at different stages of their formation are also presented.

Impact-fatigue strength of medium-carbon high-nickel steel

1. Medium-carbon nickel steels with σb = 180–190 kgf/mm2 have high impact-fatigue strength and can be recommended as structural materials for machine parts subject to cyclic impact loads. 2. Raising the nickel content of medium-carbon steel (0.4%) from 10 to 14% permits a substantial increase of the impact-fatigue strength. 3. The γ→α transformation occurs in medium-carbon nickel steels with cyclic impact loading. This substantially increases the number of cycles to failure of steel 40N14 at cyclic stresses σmax ≤ 240 kgf/mm2. 4. With σmax> 240 kgf/mm2 the presence of a large quantity of retained austenite in steel 40N14 leads to a reduction of resistance to repeated impact, since relaxation processes occur to a lesser extent in newly formed crystals of martensite with high rates of crack propagation.

Thermal stabilization of austenite in a high-nickel steel

The kinetics of the thermal stabilization of austenite have been studied in a 0.5 pct C 19 pct Ni steel within the range +300°C to -78°C. The Kinsman-Shyne model for stabilization is seen to be inadequate outside the temperature range +150°C to -20°C for this alloy. Stabilization at subzero temperatures can exhibit thermal reversibility without, however, requiring the fundamental mechanism itself to be similarly reversible.

Electron Microscopy and Diffraction Study of the Carbide Precipitated from Martensitic Low and High Nickel Steels at the First Stage of Tempering

Electron Microscopy and Diffraction Study of the Carbide Precipitated from Martensitic Low and High Nickel Steels at the First Stage of Tempering

Nature of axial ratio anomalies of the martensite lattice and mechanism of diffusionless γ → α transformation

The results of recent X-ray and neutron studies of axial ratio anomalies associated with carbon atom distributions in the tetragonal martensite lattice are analyzed. This analysis shows that the C-atom distribution in freshly formed martensite is usually partly disordered except for some Al and high-nickel steels in which all the C-atoms are on a single sublattice of octahedral interstitial sites. The disorder is only possible if the diffusionless γ → α a rearrangement differs from that assumed in the conventional theory. A possible mechanism due to Roitbourd and Khachaturyan, for the formation of “abnormal”, partially disordered martensite with a comparatively low axial ratio involves (011) α transformation twinning. New values of the concentration coefficients of linear expansion of martensite crystal, corresponding to the case when 100% of C-atoms are in a single sublattice of octahedral interstices are deduced and used for calculation of the strain-induced energies of pairs of C-atoms. Order-disorder processes are described, and the influence of correlation effects are considered. The statistical calculation leads to the conclusion that equilibrium correlations in the arrangement of C-atoms leads to an increase of the order-disorder phase transition temperature. Ordered (tetragonal) martensite at room temperature should be observed from ~0.18 wt. %C without correlation effects and from 0.0045 wt. %C if correlation is present.

The Thermal Stabilization of Austenite in High-Nickel Steels

AbstractThe thermal stabilization of austenite has been studied in two high-nickel steels which transformed to martensite at sub-zero temperatures; the martensite was of {259}γ habit in one alloy and predominantly of {225}y in the other. In both steels appreciable stabilization was obtained after ageing between the ambient temperature and ⊂ 90°C. The observations are considered in the light of the previously proposed theories for stabilization. It is concluded that stabilization at well below O°C is due to stress-relaxation, although as the temperature of stabilization is raised the diffusion of carbon may become an increasingly important factor. The influence of habit plane of the martensite on stabilization supports the concept that the controlling mechanism acts to inhibit nucleation of the martensite.

Corrosion cracking of austenitic chromium-nickel stainless steels

1. With increasing nickel concentrations the susceptibility of Cr−Ni austenitic steels to transcrystalline corrosion cracking decreases. The steels with 40% Ni are completely resistant. 2. For steels with an austenitic structure an increase of the carbon content from 0.005–0.006 to 0.075–0.087 is accompanied by an increase of the resistance to corrosion cracking, which is revealed only by tests of the long-term corrosion strength and is evidently due to an increase of the yield strength. 3. In chloride solutions the corrosion cracking of austenitic steels is primarily transcrystalline. For high-nickel steels (40%) intercrystalline attack to a depth of 0.2 mm is observed in some cases.

Creep of steels 1Yu7Kh2S1 and 1Yu7Kh2N3S1T2

1. The creep limit of experimental steel 1Yu7Kh2N3S1T2 at 800, 900, and 1000° after testing for 200–600 h is higher than that of standard high-chromium and high-nickel steels Kh25T and Kh23N13. 2. The heat resistance of experimental steel 1Yu7Kh2S1 is higher than that of standard steel Kh25T but inferior (by a factor of 1.2.-3) to that of Cr−Ni steel Kh23N13.

The precipitation of epsilon-carbide in twinned martensite

Tempering of martensite has been investigated by means of thin foil electron microscopy in a high carbon steel, a high nickel steel, and a silicon steel. e carbide has been unambiguously identified in each steel. It was found that the carbide was precipitated with the Jack orientation relationship: $$\begin{gathered} \left( {0001} \right)_\varepsilon \parallel \left( {011} \right)_{\alpha '} \hfill \\ \left( {10\bar 10} \right)_\varepsilon \parallel \left( {2\bar 11} \right)_{\alpha '} \hfill \\ \end{gathered} $$

The tempering of a low-carbon internally twinned martensite

The first stage of tempering of high-carbon martensites results in the precipitation of the metastable epsilon carbide; in low-carbon steels, it is generally considered that epsilon carbide does not form during tempering and only cementite is observed. Since high-carbon steels have an internally twinned martensite morphology, whereas low-carbon martensite (with the exception of high-nickel steels) consists of laths, it is not clear whether the first stage of tempering is controlled by carbon content or by martensite substructure. Therefore, a study was made of the tempering characteristics of a low-carbon steel in which the martensite was internally twinned. The steel chosen for this investigation contained 28 per cent nickel and 0.1 per cent carbon. Dark-field transmission electron microscopy revealed the presence of carbide precipitates in specimens that had been tempered for 48 hr at 100°C. Selected-area diffraction established that these carbides were the h.c.p. epsilon carbide. This indicates that the first stage of tempering of martensites containing carbon may be more directly related to the martensite morphology than to the carbon content alone.

Strain hardening of martensite in high-nickel steels

After 15% cold deformation (rolling) of the quenched samples the hardness increased from HV 500 to HV 560 (Fig. la). Subsequent heating at 100~ for 1 h induces further increase of the hardness from I-IV 560 to HV 605. Tempering at 150 and 200~ has almost no effect on the hardness, and only at higher temperatures does the hardness decrease. At all tempering temperatures the hardness of the cold worked samples remained higher than for the undeformed samples. The difference persisted after the reverse transformation, which leads to the conclusion that a portion of the structural defects created by cold working is retained up to high temperatures. After deformation of the quenched samples the width of (220) not only does not increase but even decreases somewhat (Fig. lb). Heating at 100-150~ leads to further reduction in the width of (220). At tempering temperatures above 200-250~ the line width decreases sharply. The reduced width of the martensite line resulting from deformation may be due to such processes as reduction of the carbon concentration in the solid solution on formation of carbides, the interaction of carbon atoms with dislocations, and disordering of the solid solution of carbon in the tetragonal lattice of martensite (movement of carbon from one pore to another within the lattice) [9]. The first two processes can occur only with sufficient mobility of the carbon atoms. In steels with high nickel concentrations both processes can occur at a fairly rapid rate at room temperature. In steel with 0.45% C and 0.22% Ni the carbide precipitates after tempering at 60~ attain such sizes that they can be seen in thin foils in the electron microscope [10]. HV