Showing papers on "Maraging steel published in 1985"

A comparison of the structural evolution occurring during anisothermal or isothermal treatments in the case of nickel and manganese type maraging alloys

Abstract: This paper reports a comparison of the structural evolution of nickel and manganese type maraging steels. The dilatometric behaviour was studied during anisothermal treatments performed at different rates. Furthermore, the evolution of the microstructure was followed during isothermal ageing with the help of electron microscopy and microdiffraction.

Alloy steel for precision plastic die parts

Abstract: PURPOSE:To produce a titled alloy steel having excellent wear resistance, strength and toughness by subjecting an alloy steel contg. a specific ratio of C, Si, Mn, P, S, Ni, Mo, Al and Ti to a soln. heat treatment and aging treatment under specific conditions. CONSTITUTION:An alloy steel consisting, by wt%, of <=0.02% C, <=0.08% Si, <=0.08% Mn, <=0.010% P, <=0.010% S, 17.0-19.0% Ni, 3.0-5.0% Mo, <=0.10% Al, 1.4-1.7% Ti and the balance iron with some impurities is prepd. The alloy steel is subjected to a soln. heat treatment from about 820 deg.C then to an aging treatment at about 470 deg.C so that the alloy steel is precipitation-hardened to about 51 HRC. The steel having the performance roughly equal to the performance of a 18Ni-5Mo-9Co type maraging steel is thus produced at a low cost.

Producing composite metal articles

Abstract: In producing a composite steel material, cylindrical steel elements (1) are first coated with nickel, manganese, copper or a combination thereof and then packed in a mild steel can (2) to produce a non- random arrangement of the elements (1) in the can (2) and wherein the packed can (2) is extruded to form a composite dual microphase billet in which fibres of martensite in the billet are completely surrounded by austenite. Flat plates can be used instead of cylindrical elements and the elements can be stacked alternately in mutually perpendicular arrays. Other metals used are niomonics titanium or maraging steel. The billet can be used for jet engine turbine blades, armour, helicopter rotor blades, car suspension stress parts or sword blades.

Dynamic aging of 18 wt-%Ni maraging 250 steel, based on studies of serrated flow

Abstract: The dynamic aging of an 18 wt-%Ni 250 maraging steel was investigated. The first stage of dynamic aging is suggested to be the formation of Mo atmospheres on dislocations, which occurs at approximately 204°C. The activation energy for Mo-atmosphere formation was found to be 1·01–1·38 eV. It is also suggested that Mo clustering in the matrix independent of the atmosphere–dislocation interaction occurs in the first stage of dynamic aging. In the later stage of dynamic aging, the Mo atmospheres are depleted from the dislocation lines by a precipitation reaction which occurs during the arrest period of the dislocations at the matrix Mo clusters. The second stage of dynamic aging (depletion of Mo atmospheres and growth of matrix Mo clusters), occurs at and above 316°C. As the growth of the Mo clusters progresses, a driving force for Ni diffusion to the clusters occurs in order to form matrix Ni3Mo precipitates. Ni diffusion to the Mo clusters occurs with an activation energy of 2·7-3·2 eV, and is consi...

A Fatigue Fracture Surface Analysis Map of the 18 Ni Maraging Steel

Abstract: The fatigue fracture surface analysis map of a 18 Ni maraging steel (see Fig. 1) is presented for the aging temperature of 482°C and the stress ratio of 0.10. The map consists of the quantitative information obtained from the analysis of fatigue fracture surface and the curve of macroscopic crack growth rate vs. stress intensity factor reported in Ref. 4). It is aimed to estimate the mode of fatigue fracture and the rate and the direction of crack growth from a fracture surface of which a cause is unknown. The effectivity of the map for the above aim is confirmed under other kinds of testing conditions, such as with the prior austenitic grain sizes of 11 μm and 25μm, the aging temperatures of 482°C and 432°C, and the stress ratios of 0.10 and 0.70.

Fracture characteristics of a burst tested maraging steel rocket motor case

Abstract: A 0.3 m diameter, 2 m long and 0.0015 m thick, 18 nickel 1800 MNm−2 grade maraging steel motor case was designed, fabricated and burst tested to gain experience for using the steel as booster case material in satellite launch vehicles. The bursting occurred at 15.2 MPa for which the effective hoop stress worked out to be 1754 MNm−2 almost equal to the ultimate tensile strength (1764 MNm−2) of the material in the solution treated and aged condition. The failure analysis revealed that the material failed due to normal tensile overload fracture. The burst test data was used to arrive at fracture mechanics parameters like crack size, gross section area stress and the stress for leak before bursting.

Steel for precise metallic mold for plastic

Abstract: PURPOSE:To obtain a steel for a precise metallic mold for plastics with high dimensional stability at a low cost by adjusting the amounts of Mo, Ti and Mn in a low carbon martensitic steel and by subjecting the resulting steel to soln. heat treatment and gas nitriding. CONSTITUTION:A steel consisting of, by weight, <=0.03% C, <=0.20% Si, 0.4- 3.0% Mn, <=0.015% P, <=0.015% S, 11.0-15.0% Ni, 2.0-5.0% Mo, 0.01-0.25% Al, 1.0-2.0% Ti and the balance Fe with few impurities is refined. The steel is subjected to soln. heat treatment at about 820 deg.C and gas nitriding at about 470 deg.C. By the nitriding, surface hardening is carried out, and at the same time, the inside is precipitation-hardened to about 51HRC. Thus, a steel for a precise metallic mold for plastics is obtd. Though this steel contains no Co and has said low Ni content, the steel is comparable to 18%Ni maraging steel in performance.

Machining-induced deformation in stepped specimens of PH 13-8 Mo, 18 nickel maraging steel grade 200T1 and grain-refined HP 9-4-20

Abstract: The results of a study to evaluate the dimensional changes created during machining and subsequent cycling to cryogenic temperatures for three different metallic alloys are presented. Experimental techniques are described and results presented for 18 Ni Grade 200 maraging steel, PH-13-8 Mo stainless steel, and Grain-refined HP 9-4-20.

Superhigh strength steel having superior delayed fracture characteristic

Abstract: PURPOSE:To obtain the titled super high-strength steel having high ductility and toughness by providing a specified composition consisting of C, Si, P, S, Ni, Mo, Co, Ti, Al, Cu, Mn and Fe. CONSTITUTION:This super high-strength steel having superior delayed fracture characteristics and >= about 200kg/mm. tensile strength consists of, by weight, <=0.03% C, <=0.1% Si, <=0.01% P, <=0.01% S, 10-10% Ni, 0.1-3% Mo, 0.1-5% Co, 0.5-3% Ti, <=0.5% Al, <=0.5% Cu, 0.2-3% Mn and the balance Fe with impurities and satisfies an equation Ni+1.5XMn=15-19%. The steel may further contain 0.005-0.05% in total of one or more among Ca, Mg and a rare earth element. The steel is obtd. by reducing the Co content of a maraging steel so as to reduce the cost while maintaining the high ductility and toughness.

Ultrahigh tensile steel for welding rod superior in thermal fatigue resisting characteristic

Abstract: PURPOSE:To manufacture a ultrahigh tensile steel for welding rod superior in fatigue resisting characteristic by using a steel material in which C-content is decreased as low as possible as a welding rod, and specified quantities of Ni, Co, Mo, Ti and Al are contained CONSTITUTION:An alloyed steel of the following composition is used as a welding rod or filler wire used for padding welding to hot tool steel and maraging steel of mold, etc for Al diecasting The alloy steel contg <005% C, 01-10% Al, 10-20% Ni, 3-10% Mo, 18-30% Co, 05-3% Ti is used Low C and a prescribed range of Ni are contained to form martensite phase having high strength, high toughness after solution treatment Specified quantities of Mo, Ti, Co, Al are contained to form metallic compounds in martensite phase after aging treatment The strength and toughness are improved, and the thermal fatigue resistance characteristic is improved

Corrosion-resistant high-strength steel having superior impact characteristic

Abstract: PURPOSE:To obtain a corrosion-resistant high-strength steel having superior impact characteristics by maintaining an essentially single martensite phase in spite of Cr contained and adopting the strengthening mechanism of a maraging steel. CONSTITUTION:The composition of a steel is composed of, by weight, =6kgm/cm impact value on the level of >=160kg/mm. strength, and it also has characteristics comparable to those of a corrosion-resistant precipitation-hardening stainless steel.

Technology for pressure-instrumented thin airfoil models, phase 1

Abstract: A network of channels was chemically milled into one surface of a pair of matched plates having bond planes which were neither planar or profiled to match the contour of the trailing edge of a supercritical airfoil for testing in cryogenic wind tunnels. Vacuum brazing bonded the plates together to create a network of pressure passages without blockages or cross leaks. The greatest success was achieved with the smaller samples and planar bonding surfaces. In larger samples, problems were encountered due to warpage created by the relief of residual stresses. Successful bonds were formed by brazing A286, Nitronic 40 and 300 series stainless steels at 1065 C using AMS 4777B brazing alloy, but excessive grain growth occurred in samples of 200 grade 18 nickel maraging steels. Good bonds were obtained with maraging steel using a 47 percent Nickel-47 percent Palladium-6 percent Silicon alloy and brazing at 927 C. Electro-Discharge-Machining was an effective method of cutting profiled bond planes and airfoil contours. Orifices of good definition were obtained when the EDM wire cut passed through predrilled holes. Possible configurations for joints between small segments and the larger main wing were also studied.

Mechanical behavior of 18 Ni 200 grade maraging steel at cryogenic temperatures

Abstract: A comprehensive study was conducted to characterize the mechanical behavior of 18 Ni 200 grade maraging steel for cryogenic applications in the National Transonic Facility. Tensile, fatigue, impact, and fracture toughness properties were determined at room and cryogenic temperatures. Experimental variables included product form, specimen orientation, and variation in metallurgical condition accomplished with a grain refining heat treatment. Room temperature tensile yield strength was approximately 200 ksi, while the yield strength at -275 F was approximately 260 ksi. Charpy V-notch energy absorption values and fracture toughness values of 18 Ni steel were found to be dependent on temperature, product form, orientation, and metallurgical condition. Fracture toughness values ranged from 80 to 113 ksi-sq rt in. at room temperature and from 67 to 90 ksi-sq rt in. at -275 F. The results of this study indicate that 18 Ni 200 grade maraging steel exceeds the strength criterion of 150 ksi minimum yield strength for use in cryogenic wind tunnel models but is marginal with respect to the 85 ksi sq rt in fracture toughness criterion at -275 F.

Aging of powder metallurgy N14K7M5T2 maraging steel

Abstract: The authors study the aging process of sintered N14K7M5T2 marging steel at temperatures of 460-590 C with an isothermal hold of 40 min to 10 h. Electron microscopy was used. The purpose of the investigations was establishment of the type of precipitated phases and their size, form, and kinetics of growth in relation to the aging cycles. An analysis of the electrondiffraction patterns of specimens aged under different conditions made it possible to identify Ni/sub 3/ Ti as the hardening phase.

Effect of residual austenite on the tendency of incompletely aged maraging steels to embrittlement during slow deformation

Abstract: 1. Embrittlement during the slow loading of incompletely aged high-strength maraging steels with titanium can be reduced when approximately 20% of residual austenite is obtained in them. 2. The required amount of austenite can be obtained by thermal cycling at temperatures of the single-phase γ-region, and also by a less complex method — heating to temperatures of the lower section of the dual-phase (α+γ)-region. 3. Maraging steel containing residual austenite in the initial state does not tend toward this type of embrittlement.

Structural strength of welded shells made of corrosion-resistant maraging steels

Abstract: 1. High structural strength is ensured for shells loaded by internal pressure when Ai.t≥10 J/cm2. For welds of corrosion-resistant maraging steels of the 03Kh11N10M2T type, this condition is satisfied when the weld strength does not exceed 1400–1450 Mpa. 2. A structural strength of 1500–1750 MPa in welds of corrosion-resistant maraging steels can obtained by means of mechanicothermal treatment (MTT).