Showing papers on "Maraging steel published in 1977"
TL;DR: In this article, the kinetics of sustained-load subcritical crack growth in hydrogen were determined for 18Ni(200) and 18Ni (250) maraging steels over a range of hydrogen pressures and temperatures.
Abstract: The kinetics of sustained-load subcritical crack growth in hydrogen were determined for 18Ni(200) and 18Ni(250) maraging steels over a range of hydrogen pressures and temperatures. Crack growth in each steel was characterized by an apparent threshold stress intensity, a domain where the growth rate increased sharply with stress intensity (K) (Stage I), and a range where the growth rate was independent ofK (Stage II). The rate-limited Stage II crack growth in these steels exhibited three distinct regions of temperature dependency, with a different isothermal pressure dependence in each region. In the low temperature region, Stage II crack growth was thermally activated with δH = 18.2 ±1.7 kj/mol; (δH being independent of hydrogen pressure and yield strength). The growth rates at a givenK were proportional to the square root of hydrogen pressure. In the intermediate temperature region, Stage II growth rates increased at slower rates, passed through a maximum and then decreased with increasing temperature. Within this region, the pressure dependence for crack growth increased from 1/2-power to 2.0-power with increasing temperature. Above a transition temperature, each grade of maraging steel became essentially immune to gaseous hydrogen embrittlement for the hydrogen pressure range considered. The transition temperature was strongly affected by yield strength and hydrogen pressure. Plausible explanations for these phenomenological results are considered.
142 citations
TL;DR: In this article, the effect of cutting speed and tool wear land length on the surface damage produced during the machining of annealed 18% nickel maraging steel under lubricated conditions was determined.
33 citations
22 citations
TL;DR: In this article, the influence of separate or simultaneous additions of Co and Mo on the structural transformations taking place during the heating cycles at moderate rates (300° Ch−1) for the Fe-Ni base alloys was studied.
Abstract: In an attempt to resolve the difficulties in interpreting the behaviour of the industrial maraging steel of VASCOMAX 300 type, we have studied the influence of separate or simultaneous additions of Co and Mo on the structural transformations taking place during the heating cycles at moderate rates (300° Ch−1) for the Fe-Ni base alloys. An interpretation of the mechanisms of the M→γ transformation, implying preponderantly diffusional mechanisms, has been proposed for the alloys Fe-Ni, Fe-Ni-Co, Fe-Ni-Mo and Fe-Ni-Co-Mo for which the Ni/Fe, Mo/Fe ratios are equal to those of the reference maraging steel. The ageing phenomena in the martensite of the alloys containing Mo have been studied and show the formation of G.P. zones having a diameter of a few tens of A and spaced at an average distance of 120 A, in the case of the quaternary alloy, at temperatures of 400 to 450° C.
15 citations
TL;DR: In this article, the authors studied the effect of strain on the room-temperature UTS of pre-crept or stress-relaxed steel, and showed that the UTS increases with the amount of plastic strain, owing to straininduced aging.
Abstract: Creep, stress relaxation, and strength at room temperature after aging under strain were studied in a 18%Ni (250) maraging steel. Creep for 3 h at 485°C (the normal aging temperature) of solution-treated alloy under a stress of 63 kg/mm2 results in about 0.8% strain, while stress relaxation from a stress 0f 60 kg/mm2 for 3 h at the same temperature yields 0.2% plastic strain. The room-temperature UTS of the pre-crept or stress-relaxed steel increases with the amount of plastic strain, owing to strain-induced aging.
11 citations
Patent•
19 Aug 1977
TL;DR: In this paper, a maraging steel of superior cold workability and high working accuracy was proposed, which is obtd. by cold working steel contg. of No, Co, Mo, Ti, Al, C, etc.
Abstract: PURPOSE: To provide a maraging steel of superior cold workability and high working accuracy osing transformation-induced plasticity, which is obtd. by cold working steel contg. limited amts. of No, Co, Mo, Ti, Al, C, etc. under specified conditions. COPYRIGHT: (C)1979,JPO&Japio
8 citations
TL;DR: In this paper, the fatigue strength of an 18% Ni maraging steel with in 108 cycles to failure was analyzed, and it was found that fatigue cracks were almost initiated from the inclusions near the surface and that the scatter of fatigue lives was mainly caused by the distribution of inclusions.
Abstract: Rotating bending fatigue tests were conducted on 18% Ni maraging steel with in 108 cycles to failure. Solution treated specimens and five kinds of aged ones having the same hardness level were tested to investigate their effects on fatigue lives. SEM observations were made on the fractured surfaces, and the distribution of fatigue lives was theoretically analyzed. The major conclusions are as follows: (1) The fatigue strength of aged 18% Ni maraging steel was higher than that of solution treated one by at least 14kg/mm2. (2) A large scatter of the fatigue lives was observed for the aged specimens, but the effect of different aging treatments was not recognized. (3) It was confirmed that the fatigue cracks were almost initiated from the inclusions near the surface, and that the scatter of fatigue lives was mainly caused by the distribution of inclusions. (4) Based on several assumptions concerning the distribution of inclusions and stress concentrations around them, the distribution of fatigue lives was theoretically derived, which showed a good agreement with the experimental distribution of lives.
8 citations
TL;DR: In this paper, the duration of crack nucleation in steels N18K9M5T and 30KhN2MFA varies little with the magnitude of cyclic stresses.
Abstract: 1.
The duration of the period of crack nucleation in steels N18K9M5T and 30KhN2MFA varies little with the magnitude of cyclic stresses.
2.
A period of slow crack growth is observed in steels 30KhN2MFA and N18K9M5T at σmax=165 kgf/mm2 and is characterized by fatigue microbands in the fracture-ductile in the maraging steel, brittle in the medium-carbon steel. With increasing crack length (period of accelerated crack growth) the area occupied by microbands in the fracture decreases and the percentage of dimpled fracture increases.
3.
At high cyclic stresses (σmax=260 and 360 kgf/mm2) the period of slow crack growth is absent in steels 30KhN2MFA and N18K9M5T.
4.
The rate of crack growth determined by the difference of electrical potentials is in satisfactory agreement with the width of fatigue microbands, particularly in the period of slow crack growth. In the period of accelerated crack growth it is somewhat higher than the width of microbands.
5.
The high regularity of fatigue microbands in the fractures of steel N18K9M5T indicates greater evenness of the properties determining the resistance to fracture at high cyclic impact loads than for steel 30KhN·2MFA.
8 citations
TL;DR: In this article, the effect of cutting speed and tool wear land length on the surface damage produced during machining of solution treated and aged 18% nickel maraging steel under lubricated orthogonal conditions was determined.
7 citations
TL;DR: In this paper, the susceptibility of 18 Ni 200 maraging steel (1380 MPa YS) to environmental cracking in 3.5% NaCI solution has been investigated.
Abstract: The susceptibility of 18 Ni 200 maraging steel (1380 MPa YS) to environmental cracking in 3.5% NaCI solution has been investigated. This alloy has been found to be susceptible to cracking due to hydrogen embrittlement, with KISCC < 26 MPa·m½ at −1.10VSCE. Deoxygenation of the salt solution has been shown to greatly decrease the time to failure when the alloy is subjected to the mildly hydrogen embrittling conditions given by coupling to cadmium.
5 citations
TL;DR: In this paper, slow, environmentally assisted crack growth has been observed during the fracture-toughness testing of a Fe-20Co-15Ni-5%Mo maraging alloy in the 'underaged' condition.
Abstract: Slow, environmentally assisted crack growth has been observed during the fracture-toughness testing of a Fe-20Co-15Ni-5%Mo maraging alloy in the ‘underaged’ condition. This phenomenon has been shown to be associated with fracture along a soft, corrosion-sensitive path at the prior austenite grain boundaries. The susceptibility of the alloy is influenced by both its oxygen content and the humidity of the environment. As ageing proceeds the effect diminishes; toughness first recovers, as microvoid coalescence develops towards peak hardness, and then falls during over ageing when a cleavage mode becomes established.
TL;DR: In this article, the total deformation of a sample under the influence of thermal cycling and uniaxial stress characterizes the resistance to thermal fatigue of die-casting molds.
Abstract: 1.
The total deformation of a sample under the influence of thermal cycling and uniaxial stress characterizes the resistance to thermal fatigue of die-casting molds.
2.
Experimental determination of the deformation makes it possible to calculate the number of cycles to failure of die-casting molds due to thermal fatigue.
3.
Calculating the thermal fatigue by the method proposed makes it possible to compare different steels. It is recommended that these calculations be made in selecting materials for die-casting molds.
4.
Maraging steel N21M2T2B is a promising material for die-casting molds used for aluminum alloys.
Patent•
12 Aug 1977
TL;DR: In this article, the authors proposed to recycle scrap maragins steel as raw material for refining maraging steel by melting the scrap in an electric arc furnace or the like and blowing oxygen to remove Ti and Al by oxidation after which vacuum melting treatment is carried out to remove C, N, S, etc.
Abstract: PURPOSE:To recycle scrap maragins steel as raw material for refining maraging steel by melting the scrap in an electric arc furnace or the like and blowing oxygen to remove Ti and Al by oxidation after which vacuum melting treatment is carried out to remove C, N, S, etc.
Patent•
16 Feb 1977
TL;DR: In this article, an 18% Ni-system maraging steel with high strength and a toughness was developed by forming the crystalline particles to an extremely minute size while preventing the particles from thermal degradation and being mixed with one another.
Abstract: PURPOSE:To provide a 18% Ni-system maraging steel having a high strength and a toughness, by forming the crystalline particles to an extremely minute size while preventing the particles from thermal degradation and being mixed with one another, when producing the 18% Ni-system maraging steel
TL;DR: Triple quenching substantially improves the ductility and toughness of embrittled steel as mentioned in this paper, and is shown to improve the ductile strength and ductility of martensitic steels.
Abstract: 1.
To prevent precipitation of excess phase in the grain boundaries and a sharp reduction of the ductility and toughness of steel 03Kh11N10M2T the steel should be cooled at a rate of at least 2·103 deg/h.
2.
To correct an original overheated structure of martensitic steels 03Kh11N10M2T, EP679, and EP699 it is necessary that they be quenched three times from 980–1000° (rapid heating to these temperatureds).
3.
Triple quenching substantially improves the ductility and toughness of embrittled steel.
Patent•
31 Jan 1977
TL;DR: Maraging steel suited for rotors of high speed hysteresis motors with high toughness at high hardness about Hr C60, tensile strength more than 200 kg/mm, residual magnetic fluxdensity more than 7,500 gauss, coersive force more than 140 Oe.
Abstract: PURPOSE:Maraging steel suited for rotors of high speed hysteresis motors with high toughness at high hardness about Hr C60, tensile strength more than 200 kg/mm , residual magnetic fluxdensity more than 7,500 gauss, coersive force more than 140 Oe
Patent•
01 Oct 1977
TL;DR: In this paper, the authors obtain Ni-Co-Mo-Ti-Al type maraging steel with extremely high strength and good ductility and toughness by increasing the amount of Ni and Mo.
Abstract: PURPOSE:To obtain Ni-Co-Mo-Ti-Al type maraging steel with extremely high strength and good ductility and toughness by increasing the amount of Ni and Mo.
TL;DR: In this paper, rods and tubes of 350 maraging steel were extruded from rotating electrode process powder and from cast-and-wrought bar stock from two sources and subjected to tests of tensile behavior and impact resistance.
Abstract: : Rods and tubes of 350 maraging steel were extruded from rotating electrode process powder and from cast-and-wrought bar stock from two sources. Samples from the rods and tubes received various heat treatments and were then subjected to tests of tensile behavior and impact resistance. The results of these tests and metallographic examination are presented and discussed as they are affected by factors such as material source and heat treatment. Consideration is given to scale-up to larger components and to means of achieving higher strength maraging steel.
Patent•
11 Apr 1977
TL;DR: In this article, a thin tube made of maraging steel having sufficiently high ductility and strength and high precision was produced by removing the ununiformity of distribution of the inner diameter by carrying out the solid solution treatment with a specified method to the tube of which the outer diameter has been expanded with the plastic working.
Abstract: PURPOSE:Producing the thin tube made of maraging steel having sufficiently high ductility and strength and, moreover, high precision, by removing the ununiformity of distribution of the inner diameter by carrying out the solid solution treatment with a specified method to the tube of which the inner diameter has been expanded with the plastic working.
Patent•
30 Mar 1977
TL;DR: In this article, the strength and the toughness of the rotary drum made of Ni maraging steel to be used for the centrifugal separator for concentrating uranium was improved by improving the Ni-maraging steel.
Abstract: PURPOSE:Improving the strength and the toughness of the rotary drum made of Ni maraging steel to be used for centrifugal separator for concentrating uranium.
Patent•
14 Dec 1977
TL;DR: In this article, the specified heat treatment for the maraging steel to which one or two kinds out of Nb and Zr have been added was performed to prevent the occurrence of grain boundary reaction and to make tough.
Abstract: PURPOSE:To prevent the occurrence of grain boundary reaction and to make tough, by performing the specified heat treatment for the maraging steel to which one or two kinds out of Nb and Zr have been added.
01 Jan 1977
TL;DR: In this article, the α-to-γ phase transformation was used in iron-base alloys strengthened by the Laves phase, TaFe2, to improve the creep strength.
Abstract: Attempts to develop alloys with thermally stable intermetallic compounds, rather than alloy carbides, as the strengthening dispersoid in ferritic steels have failed, largely because of the embrittlement resulting from precipitation of the intermetallic compound in grain boundaries during heat treatment Recent work has shown that this problem can be overcome by the appropriate use of the α-to-γ phase transformation in iron-base alloys strengthened by the Laves phase, TaFe2 The new alloys have creep strengths at 650 C that are superior to most of the commercially available ferritic steels and are comparable in creep strength to the 300-grade austenitic steels