Showing papers on "Maraging steel published in 1992"
TL;DR: In this article, an eddy current technique was used to determine the volume percent of austenite phase in 18% Ni maraging steel grade 350, which can be applied on the production floor with relative ease compared to the X-ray method.
Abstract: An eddy current technique has been used to determine the volume percent of austenite phase in 18% Ni maraging steel grade 350. The values of volume percent austenite thus obtained are compared with those obtained by an established X-ray diffraction method. The eddy current method has been shown to be very suitable for quick and quantitative determination of austenite phase which can be applied on the production floor with relative ease compared to the X-ray method.
21 citations
30 Dec 1992-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the phase transformation from martensite to austenite (α-γ) reversion is detected in grade 350 maraging steel as a result of machining processes.
Abstract: Phase transformation, i.e. martensite to austenite (α-γ) reversion, is detected in grade 350 maraging steel as a result of machining processes. The thermal stability of machine-induced austenite is found to be higher than that of the thermally produced austenite. The machined samples, when ausaged with and without prior solution annealing, exhibit different amounts of austenite formation at same ausaging temperatures. The austenite start temperature for machined samples is found to be lower than for the unmachined samples. Texture measurements of machine-induced and thermally produced austenites are also reported.
13 citations
TL;DR: In this paper, an embrittled 18 Ni maraging steel ring was examined and samples cut from the ring were subjected to a wide range of heat treatments including high temperature solutioning and thermal cycling.
Abstract: An embrittled 18 Ni maraging steel rolled ring was examined and samples cut from the ring were subjected to a wide range of heat treatments including high temperature solutioning and thermal cycling. The effects of these treatments on toughness were evaluated by measuring impact energy and plain strain fracture toughness. The microstructural analyses were carried out using extensive optical and scanning electron microscopy, and scanning electron fractography. It has been established that the ring was embrittled due to the combined effects of deformed structure and grain boundary precipitation of TiC or Ti (CN). Heat treatment parameters have been devised to improve the fracture toughness and grain size of the materials affected by these two types of embrittlement. It has been suggested that toughness and grain size can be improved by (a) annealing at 1223 K followed by water quenching in the case where deterioration in toughness is marginal and is caused by nonrecrystallized grains or deformation texture, and (b) solutioning at 1473 K followed by water quenching, and thermal cycling twice between room temperature and 1198 K with a holding time of 30 min at peak temperature in the case where the loss in toughness is considerably large due to excessive grain boundary precipitation of second phase particles.
12 citations
TL;DR: In this article, the effect of hydrogen embrittlement on the tensile properties and fracture characteristics of 18 Ni 1800 MPa (M250) grade maraging steel was investigated.
Abstract: Specimens of 18 Ni 1800 MPa (M250) grade maraging steel were charged with different quantities of hydrogen by an electrochemical method. The tensile properties and fracture characteristics have been correlated with the quantity of hydrogen picked up by the material. A drastic decrease in ultimate tensile strength from 1768 M Pa to 750 M Pa, elongation from 6% to less than 2%, and reduction in area from 55% to less than 5%, were observed as the hydrogen content of the steel increased from less than 2 p.p.m. to 7 p.p.m. However, hydrogen does not affect the hardness of the steel. The effect of baking at different temperatures on hydrogen embrittlement was also studied. A change in fractographic features from ductile dimples to mixed mode, intergranular separation and transgranular cleavage was observed as the amount of absorbed hydrogen increased.
11 citations
TL;DR: In this paper, the crystal structure and chemical composition of the strengthening precipitates in an Fe-11.8 pct Cr-8.5 pct Ni-1.8pct Mo martensite + ferrite duplex steel were determined by transmission electron microscopy (TEM).
Abstract: The crystal structure and chemical composition of the strengthening precipitates in an Fe- 11.8 pct Cr-8.5 pct Ni-1.8 pct Ti-3.8 pct Mo martensite + ferrite duplex steel were determined by transmission electron microscopy (TEM). The study revealed that a metastable precipitate phase formed in the ferrite and martensite phases during the initial stages of aging. The meta- stable phase was proposed to have a hexagonal crystal structure similar to that reported for the omega phase in Ti alloys. Prolonged aging formed an equilibrium orthorhombic precipitate phase with a Ni3(Mo, Ti) stoichiometry. The higher dislocation density in martensite accelerated the precipitation reaction, and the transition to the equilibrium precipitate occurred with shorter aging times compared to ferrite. The details of the electron diffraction and analytical electron microscopy studies of the precipitates are described.
9 citations
8 citations
TL;DR: In this article, an atom probe field-ion microscopy (APFIM) study of the ageing reactions in a model Fe 18.2%Ni 8.8%Co 2.9% Mo (at. %) maraging steel was performed.
7 citations
TL;DR: In this paper, the authors investigated the structure, properties and phase transformations of maraging steel while quenching from the liquid state and found that, depending on the solidification rates and subsequent cooling, the formation of highly dispersed structures in the solid phase was possible.
Abstract: Peculiarities of structure, properties and phase transformations in the maraging steel were investigated while quenching from the liquid state. Depending on the solidification rates and subsequent cooling, the formation of highly dispersed structures in the solid phase was possible. The structures were of the following types: fully martensite, fully ferrite; a mixture of ferrite and martensite or martensite and austenite.
5 citations
Journal Article•
TL;DR: In this paper, the influence of the aging temperature, phase composition and stability of the reversed austenite on the complex of mechanical properties and fatigue strength of maraging steels was considered.
Abstract: Mechanical and fatigue properties of two maraging steels, 03Kh10N8K10M5T and 03Kh11N10M2T, were investigated after various heat treatments. The influence of the aging temperature, phase composition and stability of the reversed austenite on the complex of mechanical properties and fatigue strength of maraging steels was considered
5 citations
TL;DR: In this article, the microstructural aspects of the maraging steel weld repair have become important as this material finds extensive applications in aerospace and other strategic areas, and the details available on these at present are very limited.
Abstract: The study of the microstructural aspects of the maraging steel weld repair has become important as this material finds extensive applications in aerospace and other strategic areas. The details available on these at present are very limited. During one of the fabrication trials of a large pressure vessel made of 18 Ni 1800 MPa maraging steel plates, 7.8 mm thick, defects were observed in the welds which were to be repaired. This called for simulated experiments. The microstructural variations observed in the repaired areas were the result of the repeated thermal cycles they had undergone. Based on this microstructural evidence, a new diagram depicting the newly formed weld zones is constructed from which the mechanical properties of the repair welds can be predicted.
3 citations
Patent•
26 Feb 1992
TL;DR: In this paper, a hot formed maraging steel containing, by weight, = 1min, cooling at >=20 deg.C for >=1min, and cooling is carried out.
Abstract: PURPOSE:To stably produce a maraging steel securing high strength and having mechanical properties well balanced among tensile ductility, Charpy impact value, and fracture toughness by subjecting a steel containing specific amounts of C, Si, Mn, P, S, Ni, Ti, and B as basic components to hot forming and then to specific recrystallization solution treatment. CONSTITUTION:A hot formed maraging steel containing, by weight, =1min, cooling at >=20 deg.C/min cooling rate, further heating up to 800-950 deg.C for >=1min, and cooling is carried out. By this method, the maraging steel excellent in strength, toughness, and ductility can be obtained.
01 Aug 1992-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the microstructure of the solution-treated and subsequently quenched maraging steel consists of fully lath martensite with a high dislocation density, and a twin relationship between some adjacent martensitic laths is observed.
Abstract: The crystallographic characteristics of martensitic laths in Fe10Cr10Ni2W maraging steel have been investigated using electron diffraction patterns. The microstructure of the solution-treated and subsequently quenched maraging steel consists of fully lath martensite with a high dislocation density. A twin relationship between some adjacent martensitic laths is observed. It is identified that the twinned laths are transformed from the austenite of two specific variants with a Kurdjumov-Sachs orientation relationship.
Patent•
10 Jun 1992
TL;DR: In this article, a hot formed maraging steel is subjected to solution heat treatments twice in specified conditions, in order to obtain Charpy impact characteristics without requiring addition of B.C for more than one minute.
Abstract: PURPOSE:To manufacture a maraging steel excellent in strength, toughness and ductility by subjecting a hot formed maraging steel to solution heat treatments twice in specified conditions. CONSTITUTION:The fot formed maraging steel has a compsn. composed of, by wt.% =20 deg.C/min cooling rate, further heating at 800-950 deg.C for more than one minute, and then cooling. By above- mentioned heat treatment, the maraging steel excellent in strength, toughness tensile ductility and Charpy impact characteristics can be obtained without requiring addition of B.
01 Jan 1992
TL;DR: In this article, the low cycle fatigue behavior and crack initiation of an age hardenable AlZnMgCu-alloy, a high nickel austenitic steel and an ultra-high strength maraging steel have been studied.
Abstract: The low cycle fatigue behaviour and crack initiation of an age hardenable AlZnMgCu-alloy, a high nickel austenitic steel and an ultra-high strength maraging steel have been studied. The tests were performed in laboratory environment at room temperature in push-pull cycles with constant strain amplitudes of 0.2 to 2 per cent. Crack initiation investigations were performed using bending specimens loaded by a resonance bending machine. Crack growth was measured using the replica method.
01 Jan 1992
TL;DR: In this paper, the effect of strain rate in range 10−4to 10−7s−1 on yield strength and ultimate tensile strength to 673K was negligible.
Abstract: The effect of strain rate in range 10–4to 10–7s–1on yield strength and ultimate tensile strength to 673K is negligible. Uniform strain and fracture strain decrease when dynamic strain aging takes place. Fracture toughness JIc at 573 and 637K is higher than at 293K. The slope of the resistance curve at high temperature decreases when dynamic strain aging occurs.