Showing papers on "Maraging steel published in 1991"

Penetration of Strain-Hardening Targets With Rigid Spherical-Nose Rods

Abstract: The spherical cavity expansion approximation simplified the target analysis. To verify our models, we conducted terminal-ballistic experiments with three projectile geometries made of maraging steel and 6061-T651 aluminum targets for impact velocities between 0.3 and 1.0 km/s

Alloys of iron and reversibility of martensitic transformations

Abstract: The origin of irreversibility, reversibility, course and completeness of martensitic transformations are discussed using the following alloys of iron as examples: 1. I~reversible transformation: Fe-C, Fe-Nix, maraging steel 2. Reversibility in homogeneous solid solutions: Fe-Ni, Fe-Ni-C, Fe-Mn 3. Reversibility due to order or coherent particles: Fe-Pt, Fe--Ni-X, Fe-Ni-Co-Ti 4. Effects of external stress and mechanical properties on Ms 5. Effects of external magnetic fields and magnetism/antiferromagnetism in austenite. The feasibility of shape memory steels is finally discussed.

Development of new low nickel, cobalt free maraging steel

Abstract: A new low Ni, Co free maraging steel containing 12Ni–3·2Cr–5·1Mo–ITi (wt-%) has been developed. The optimum heat treatment was found to be solution treatment at 1098 K for 60 min followed by air cooling then aging at 753 K for 180 min. Detailed optical and transmission electron microscopy revealed that the solution treated steel transformed to lath martensite. The optimised steel achieved an ultimate tensile strength of 1700 MN m−2 and a yield strength of 1660 MN m−2. The toughness measured in terms of impact energy was found to be 38 J. Fractographic analysis carried out in the scanning electron microscope showed predominantly dimpled structures indicating ductile failure. The transformation temperatures for this new steel were established using dilatometry.MST/1398

Grain growth in 18Ni 1800 MPa maraging steel

Abstract: The grain-growth behaviour in 18Ni8Co5MoO.4Ti maraging steel was investigated in the temperature range 1123–1323 K. Grain sizes were estimated by measuring the diameter of the equivalent area of the individual grains directly on the optical microscope using a calibrated digital eyepiece. Grain-boundary migrations and substructure analyses were done using an electron microscope. These studies indicate that the overall grain growth in the steel follows the relationship ΔD=ktn where ΔD is the increase in the grain size. However, during the initial stage, a “time lag” for the grain growth to start is observed which is attributed to the presence of highly dislocated austenitic matrix on annealing. Evidence of abnormal grain growth is also seen after annealing at 1173 K for 480 min and at 1123 K for 300 min. The growth exponents for the normal and abnormal grain growth were found to be 0.40–0.44 and 0.90–2.0, respectively. One significant deviation observed in the study wasn decreasing from 0.44-0.40 at higher temperatures during the normal growth. This has been critically discussed in the light of the unique transformation characteristics of the steel. The activation energy for growth was calculated to be 60.0–62.5 kcal mol−1, indicating the overall growth is controlled by self diffusion in γ-iron.

Heat treatment of maraging steel

Abstract: PURPOSE:To improve the soft magnetic characteristics of an 18Ni maraging steel by subjecting the maraging steel to a soln. heat treatment and aging treatment respectively in specific temp. ranges. CONSTITUTION:For example, the 18Ni maraging steel is subjected to the soln. heat treatment at 850 to 1100 deg.C and is then subjected to the aging treatment at 430 to 480 deg.C. The aging time is adequately 0.1 to 20 hours and is more preferably 1 to 5 hours. The maraging steel having the better soft magnetism than the soft magnetism of the maraging steel obtd. by the conventional heat treatment methods is obtd. by subjecting the maraging steel to the above-mentioned heat treatment.

The formation of twinned austenite in fe-10cr-10ni-2w maraging-steel

Abstract: The precipitation hardening mechanisms in high strength maraging steels have been studied in detail by many investigators, but limited information is available on the formation of austenite during aging. Some investigations have been concerned with the understanding of the effect of reverted austenite formed during aging on the mechanical properties. However, only a few investigations have been reported on the morphology and crystallographic feature of austenite. Shiang and Wayman first reported the twin-related and coupled morphology of Widmanstatten austenite plates which were frequently observed in maraging steel. In addition, Ameyama et al. reported the morphology and crystallographic features of austenite formed in ferrite grain during aging in a two-phase stainless steel, and found that each side of the austenite pair of twins satisfies the Kurdjumov-Sachs (K-S) orientation relationship with the parent phase. The morphology and crystallographic features of the reverted austenite formed during aging of Fe-10Cr-10Ni-2W stainless maraging steel have been investigated in this paper. The major strengthening precipitate in Fe-10Cr-10Ni-2W maraging steels has been identified as the rod-shaped {eta}-Ni{sub 3}Ti phase in our previous study. The peculiar morphology of the austenite, i.e., twinned austenite, also has been found in our studies of maraging steel in the Fe-10Cr-10Ni-2W lath martensite.more » In addition, computer simulation of the diffraction pattern is used to confirm the orientation relationships, such as the Kurdjumov-Sachs (K-S) relationship, the Nishiyama-Wasserman (N-W) relationship and the twin relationship by comparisons with the experimentaly observed results.« less

Stainless maraging steel having high strength, high toughness and high corrosion resistance and it's manufacturing process

Abstract: A stainless maraging steel and process having high strength, high toughness and high corrosion resistance. The alloy consists of from 8 to 12% by weight Cr, 7 to 12% by weight Ni, 2 to 6% by weight W, 0.1 to 0.5% by weight Al, 0.1 to 0.4% by weight Ti, and the balance iron.

Effect of the type of stress state on the micromechanisms of failure of maraging steels during equilibrium deformation

Abstract: Fractographic and microstructural results are presented on the equilibrium failure of samples made of maraging steel, including those carrying stress concentrators of various form. It has been shown that it is possible to trace the actual micromechanism of failure of ductile materials during the growth and development of microcracks in terms of the stress state.

Braze alloy process and strength characterization studies for 18 nickel grade 200 maraging steel with application to wind tunnel models

Abstract: A comprehensive study of braze alloy selection process and strength characterization with application to wind tunnel models is presented. The applications for this study include the installation of stainless steel pressure tubing in model airfoil sections make of 18 Ni 200 grade maraging steel and the joining of wing structural components by brazing. Acceptable braze alloys for these applications are identified along with process, thermal braze cycle data, and thermal management procedures. Shear specimens are used to evaluate comparative shear strength properties for the various alloys at both room and cryogenic (-300 F) temperatures and include the effects of electroless nickel plating. Nickel plating was found to significantly enhance both the wetability and strength properties for the various braze alloys studied. The data are provided for use in selecting braze alloys for use with 18 Ni grade 200 steel in the design of wind tunnel models to be tested in an ambient or cryogenic environment.

Maraging steel with high ductility and toughness

Abstract: Maraging steel with high ductility and toughness, exhibiting an improved fatigue resistance, usable especially in the manufacture of turbine shafts for aircraft engines, characterised in that its weight composition includes: - from 14 to 19 % of nickel, - from 9 to 14 % of cobalt, - from 5 to 8 % of molybdenum, the nickel and molybdenum contents satisfying the relationship: and in that it contains from 0.005 to 0.05 % of an element belonging to the rare-earth series.

Soft magnetic and high strength steel

Abstract: PURPOSE:To obtain the soft magnetic and high strength maraging steel in which expensive Co is not necessarily required by adding a specified amt. of Cu to a conventional maraging steel and regulating the content of other components. CONSTITUTION:As a soft magnetic and high strength material as a yoke material and a relay material for a rotor of an induction motor, a maraging steel having the compsn., contg. by weight, =12KG magnetic flux density as well as having >=140kgf/mm tensile strength can be obtd.

Advances in powder metallurgy - 1991. Vol. 5 - P/M materials; Proceedings of the Powder Metallurgy Conference and Exhibition, Chicago, IL, June 9-12, 1991

Abstract: The present volume powder metallurgy materials discusses the state of the PM industry, a metallurgical evaluation of new steel powders, design criteria for the manufacturing of low-alloy steel powders, and homogenization processing of a PM maraging steel. Attention is given to the corrosion resistance of full density sintered 316 SS, the performance characteristics of a new sinter-hardening low-alloy steel, wear performance of compositions made by low alloy iron/high alloy powder mixtures, and the strengthening of an AISI 1020 steel by aluminum-microalloying during liquid dynamic compaction. Topics addressed include the influence of alloying on the properties of water-atomized copper powders, fundamentals of high pressure gas atomization process control, advanced sensors and process control of gas atomization, and bimetallic tubulars via spray forming. Also discussed are factors affecting the delamination of PM molybdenum during stamping, applications of powder metallurgy molybdenum in the 1990s, and powder processing of high-temperature oxides.

Production of maraging steel having high fatigue strength

Abstract: PURPOSE:To remarkably improve the fatigue strength of a maraging steel by carrying out ageing treatment in the stages before and after the stage where a maraging steel after solution treatment is worked and formed into the desired shape CONSTITUTION:After solution treatment is applied to a maraging steel at high temp, ageing treatment is applied to the maraging steel at a temp lower than the solution treatment temp, by which the mechanical properties of the maraging steel is improved and the occurrence of fine cracks in the surface is prevented although subsequent working and forming are made difficult to some degree, and further, the steel is worked or formed into the desired shape Subsequently, ageing treatment is applied again to the above steel at a temp slightly higher than the above ageing treatment temp and lower than the solution treatment temp, by which inversely transformed austenitic phase can be properly precipitated in the base phase in the steel structure and fatigue strength can be improved without causing much deterioration in tensile strength and hardness

01N17K12M5T Maraging steel under conditions of superfast solidification and high-speed pressing

Abstract: During rapid hardening of 01N17K12M5T steel there are significant changes in its structure and properties. The grain size becomes finer, there is a reduction in the degree of chemical inhomogeneity, and the hardness increases. Foils produced by the “hammer and anvil” method have an extremely dispersed martensitic structure with a martensitic plate width of 0.3–0.4 μm and a hardness of up to 10,000 MPa, which, is an indication of the decisive role of interfaces in strengthening of metal.