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Showing papers on "Tempering published in 1978"


Journal ArticleDOI
TL;DR: In this article, the authors investigated the role of interlath films of retained austenite in TME and found that the embrittlement was concurrent with the inter-lath precipitation of cementite during tempering and the consequent mechanical instability of retained Austenite during subsequent loading.
Abstract: An investigation into the mechanisms of tempered martensite embrittlement (TME), also know as “500°F” or “350°C” or one-step temper embrittlement, has been made in commercial, ultra-high strength 4340 and Si-modified 4340 (300-M) alloy steels, with particular focus given to the role of interlath films of retained austenite. Studies were performed on the variation of i) strength and toughness, and ii) the morphology, volume fraction and thermal and mechanical stability of retained austenite, as a function of tempering temperature, following oil-quenching, isothermal holding, and continuous air cooling from the austenitizing temperature. TME was observed as a decrease in bothKIc and Charpy V-notch impact energy after tempering around 300°C in 4340 and 425°C in 300-M, where the mechanisms of fracture were either interlath cleavage or largely transgranular cleavage. The embrittlement was found to be concurrent with the interlath precipitation of cementite during temperingand the consequent mechanical instability of interlath films of retained austenite during subsequent loading. The role of silicon in 300-M was seen to retard these processes and hence retard TME to higher tempering temperatures than for 4340. The magnitude of the embrittlement was found to be significantly greater in microstructures containing increasing volume fractions of retained austenite. Specifically, in 300-M the decrease inKIc, due to TME, was a 5 MPa√m in oil quenched structures with less than 4 pct austenite, compared to a massive decrease of 70 MPa√m in slowly (air) cooled structures containing 25 pct austenite. A complete mechanism of tempered martensite embrittlement is proposed involving i) precipitation of interlath cementite due to partial thermal decomposition of interlath films of retained austenite, and ii) subsequent deformation-induced transformation on loading of remaining interlath austenite, destabilized by carbon depletion from carbide precipitation. The deterioration in toughness, associated with TME, is therefore ascribed to the embrittling effect of i) interlath cementite precipitates and ii) an interlath layer of mechanically-transformed austenite,i.e., untempered martensite. The presence of residual impurity elements in prior austenite grain boundaries, having segregated there during austenitization, may accentuate this process by providing an alternative weak path for fracture. The relative importance of these effects is discussed.

234 citations


Journal ArticleDOI
TL;DR: The problem of detecting the distribution of small amounts (5 pct or less) of retained austenite films around the martensite in quenched and tempered experimental medium carbon Fe/c/x steels is discussed in this article.
Abstract: The problems of detecting the distribution of small amounts (5 pct or less) of retained austenite films around the martensite in quenched and tempered experimental medium carbon Fe/c/x steels are discussed and electron optical methods of analysis are emphasized. These retained austenite films if stable seem to be beneficial to fracture toughness. It has been found that thermal instability of retained austenite on tempering produces an embrittlement due to its decomposition to interlath films of M3C carbides. The fractures are thus intergranular with respect to martensite but transgranular with respect to the prior austenite. The temperature at which this occurs depends upon alloy content. The effect is not found in Fe/Mo/C for which no retained austenite is detected after quenching, but is present in all other alloys investigated.

219 citations


Journal ArticleDOI
TL;DR: In this article, a study of the influence of austenitizing temperature on the ambient temperature toughness of commercial AISI 4340 ultra-high strength steel in the as-quenched (untempered) and quenched and tempered at 200°C conditions was made.
Abstract: A study has been made of the influence of austenitizing temperature on the ambient temperature toughness of commercial AISI 4340 ultrahigh strength steel in the as-quenched (untempered) and quenched and tempered at 200°C conditions. As suggested in previous work, a systematic trend ofincreasing plane strain fracture toughness(K)Ic anddecreasing Charpy V-notch energy is observed as the austenitizing temperature is raised while the yield strength remains unaffected. This effect is seen under both static and dynamic (impact) loading conditions, and is rationalized in terms of a differing response of the microstructure, produced by each austenitizing treatment, to the influence of notch root radius on toughness. Since failure in all microstructures was observed to proceed primarily by a ductile rupture (microvoid coalescence) mechanism, an analysis is presented to explain these results, similar to that reported previously for stress-controlled fracture, based on the assumption that ductile rupture can be considered to be strain-controlled. Under such conditions, the decrease in V-notch Charpy energy is associated with a reduction in critical fracture strain at increasing austenitizing temperatures, consistent with an observed decrease in uniaxial and plane strain ductility. The increase in sharp-crack fracture toughness, on the other hand, is associated with an increase in “characteristic distance” for ductile fracture, resulting from dissolution of void-initiating particles at high austenitizing temperatures. The microstructural factors which affect this behavior are discussed, and in particular the specific role of retained austenite is examined. No evidence was found that the enhancement of fracture toughness at high austenitizing temperatures was due to the presence of films of retained austenite. The significance of this work on commonly-used Charpy/KIc empirical correlations is briefly discussed.

155 citations


Journal ArticleDOI
TL;DR: In this article, a structural model was developed that incorporates both stress and structural relaxation for nonisothermal conditions, and the model was compared with experimental data on tempering and contrasted with predictions of the viscoelastic model.
Abstract: Temper stresses are brought about, primarily, by a partial relaxation of transient stresses generated by rapid cooling of the glass. Stress relaxation under nonisothermal conditions is competently handled by a mathematical tempering model, in which glass is treated as a simple viscoelastic material. However, this model proved inadequate in some respects since the properties of glass depend not only on its instantaneous temperature but also on its prior thermal history. A tempering model was therefore developed that incorporates both stress and structural relaxation. Predictions of this structural model are compared with experimental data on tempering and contrasted with predictions of the viscoelastic model. Such comparisons revealed that, typically, structural relaxation accounts for approximately 24% of the total residual temper stresses.

154 citations


Book
01 Sep 1978
TL;DR: In this paper, the authors present an approach for the separation of metal components based on the properties of the metal components and their properties, such as properties of fracture in a Ductile Material, fracture in Brittle Material, deformation in a Brittle material, and reduction of brittle fracture.
Abstract: 1 Introductory Materials Concepts Chp 1.Structure and Properties 1-1 Atomic Packing 1-2 Crystal Structure 1-3 Grain Structure 1-4 Mechanical Properties and Testing 1-5 Physical Properties Chp 2.Deterioration of Material Properties 2-1 Fracture in a Ductile Material 2-2 Fracture in a Brittle Material 2-3 Suppression of Brittle Fracture 2-4 Linear Elastic Fracture Mechanics 2-5 Property Deterioration 2-6 Property Deterioration from Cyclic Loading 2 Strengthening Mechanisms Chp 3.Solid-Solution Strengthening 3-1 Formation of Solid Solutions 3-2 Mechanism of Solidification 3-3 Solidification of Pure Metals 3-4 Solidification of Metal Alloys 3-5 Diffusion 3-6 Segregation in Metal Alloys 3-7 Real Solid Solutions 3-8 General Properties of Solid Solutions Chp 4.Deformation Hardening and Annealing 4-1 Plasticity of Metals 4-2 Property Changes in Deformation Hardened Metals 4-3 Annealing 4-4 Property Changes in Annealed Metals Chp 5.Multiphase Stregthening 5-1 Binary Eutectics 5-2 Intermetallic Compounds 5-3 Multicomponent Eutectics 5-4 Microstructure of Multiphase Materials 5-5 Generalized Properties of Multiphase Materials Chp 6.Precipitation Hardening 6-1 General Mechanism of Precipitation Hardening 6-2 Precipitation from Solid Solution 6-3 Stages of Precipitation Hardening 6-4 Variables Affecting Precipitation Hardening 6-5 Prcippitation Hardening of Cu-Be Alloys Chp 7.Martensitic Transformation 7-1 The Fe-Fe3C Phase Diagram 7-2 Alloys of Iron and Carbon 7-3 Microstructure of Nonhardened Steel 7-4 Heat Treatment of Eutectoid Steel 7-5 The Martensite Transformation 7-6 Heat Treatment of Noneutectoid Steel 7-7 Physical Property Changes during Martensite Formation 7-8 Tempering of Martensite 7-9 Microstruture of Isothermally Transformed Steel 7-10 Generalized Properties of Heat-Treated Steel 3 Metallic Materials Engineering Chp 8.Low-Carbon Steels 8-1 Terms Related to Steelmaking Processes 8-2 Grain Size of Steel 8-3 Nonhardenable Low-Carbon Steels 8-4 High-Strength Low-Carbon Steel Chp 9. Medium Carbon Steels 9-1 Classification of Medium Carbon Steels 9-2 Hardening Carbon Steels 9-3 Hardening Alloy Steels 9-4 Ultra High-Strength Steels Chp 10.High Carbon Steels 10-1 Classification of High-Carbon Steels 10-2 Heat Treatment of High-Carbon Steels 10-3 Cemented Carbides Chp 11.Stainless Steels 11-1 Phase Diagrams of Stainless Steels 11-2 Stainless Steel Alloy Designations 11-3 Heat Treatment of High-Carbon Steels 11-4 Mechanical Properties of Stainless Steels 11-5 Corrosion Resistance of Stainless Steels Chp 12.Cast Irons 12-1 Cast Iron (Fe-C-Si)Phase Diagram 12-2 Gray Cast Iron Solidification 12-3 Ductile Cast Iron Solidification 12-4 Concepts of Graphitization in Cast Iron 12-5 Properties of Cast Iron Chp 13.Aluminum Alloys 13-1 Work Hardenable Wrought Aluminnum Alloys 13-2 Heat Treatable Aluminum Alloys 13-3 Cast Aluminum Alloys 13-4 Residual Stresses in Aluminum Alloys 13-5 Alumminum-Lithium Alloys Chp 14.Copper and Copper Alloys 14-1 Copper Alloy Designations 14-2 Unalloyed Coppers 14-3 Brasses:Cu-Zn Alloys 14-4 Tin Bronzes: Cu-Sn Alloys 14-5 Silicon and Aluminum Bronzes 14-6 Cast Copper-Based Alloys Chp 15.Magnesium Alloys 15-1 Magnesium Alloy Designations 15-2 The Nature of Magnesium Alloying 15-3 Cast Magnesium Alloys 15-4 Properties of Magnesium Alloys Chp 16.Titanium Alloys 16-1 Unalloyed Titanium 16-2 Phase Diagrams of Titanium Alloys 16-3 Heat Treatment of Titanium Alloys 16-4 Properties of Titanium Alloys 16-5 Applications of Titanium Alloys Chp 17.Metals for High-Temperature Service 17-1 High-Temperature Performance of Refractory Metals 17-2 Nickel and Iron Based Superalloys 17-3 Cobalt Based Superalloys 17-4 Vanadium, Niobium, and Tantalum 17-5 Chromium, Molybdenum,and Tungsten 17-6 Refractory Metal Coatings 4 Nonmetallic Materials and Composites Engineering Chp 18.Engineering Polymers 18-1 Bonding and Structure in Polymers 18-2 Generalized Properties of Polymers 18-3 Olefin, Vinyl, and Related Polymers 18-4 Thermoplastic Polymers 18-5 Thermosetting Polymers 18-6 Elastomeric Polymers Chp 19.Ceramics and Glasses 19-1 A Ceramic Phase Diagram (A12O3-SIO2) 19-2 Traditional Ceramics: Clay, Refractories, and Abrasives 19-3 Structure and Properties of Engineering Ceramics 19-4 Characteristics Of Glass Chp 20.Composite Materials 20-1 Forms and Properties of Composite Reinforcing Materials 20-2 Forms and Properties of Composite Matrix Materials 20-3 Metal Matrix Composites 20-4 Polymer Matrix Composites 20-5 Ceramic Matrix Composites 20-6 Carbon and Graphite Composites

139 citations


Journal ArticleDOI
TL;DR: In this paper, the behavior of the thermally stable austenite in the ductile fracture surface layer of a grain-refined and tempered 9Ni steel broken at 77 K was studied through use of Moss-bauer spectroscopy and transmission electron microscopy.
Abstract: The behavior of the thermally stable austenite in the ductile fracture surface layer of a grain-refined and tempered 9Ni steel broken at 77 K was studied through use of Moss-bauer spectroscopy and transmission electron microscopy. Thin foils revealing the mi-crostructural profile of the fracture surface layer were prepared by electroplating a thick pure iron layer on the fresh fracture surface, then thinning a profile sample through a combination of conventional twin-jet electropolishing and ion milling techniques. The re-sults of both Mossbauer spectroscopy and TEM studies showed that the thermally stable austenite transforms to a dislocated martensite in the deformed zone adjacent to the duc-tile fracture surface. This result suggests that transformation of the retained austenite present in tempered 9Ni steel is compatible with low temperature toughness, at least when the transformation product is a ductile martensite.

83 citations


Journal ArticleDOI
TL;DR: In this article, the effects of silicon additions and retained austenite on the stress-corrosion cracking (SCC) behavior of commercial ultra-high strength steels (AISI 4340 and 300-M) tested in aqueous solutions were made.
Abstract: A study has been made of the effects of silicon additions and of retained austenite on the stress-corrosion cracking (SCC) behavior of commercial ultrahigh strength steels (AISI 4340 and 300-M) tested in aqueous solutions. By comparing quenched and tempered structures of 4340 and 300-M i) at equivalent strength and ii) at their respective optimum and commercially-used heat-treated conditions, the beneficial role of silicon addition on SCC re-sistance is seen in decreased Region II growth rates, with no change in K’ISCC. The beneficial role of retained austenite is demonstrated by comparing isothermally transformed 300-M, containing 12 pct austenite, with conventionally quenched and tempered structures of 300-M and 4340, containing less than 2 pct austenite, at identical yield strength levels. Here, the isothermally transformed structure shows an order of magnitude lower Region II SCC growth rates than quenched and tempered 300-M and nearly two orders of magnitude lower Region II growth rates than 4340, K ISCC values remaining largely unchanged. The results are discussed in terms of hydrogen embrittlement mechanisms for SCC in martensitic high strength steels in the light of the individual roles of hydrogen diffusivity and carbide type.

70 citations


Journal ArticleDOI
TL;DR: The effects of intercritical tempering on the impact energy of Fe-9Ni-0.1C have been investigated in this article, where the authors showed that the contribution of the localized TRIP mechanism is negligible compared with the scavenging effect of the austenite, removing deleterious impurities from the martensite and increasing its toughness.

43 citations


Patent
14 Sep 1978
TL;DR: A high strength, tough alloy steel, particularly suitable for the mining industry, is formed by heating the steel to a temperature in the austenite range (1000°-1100° C) to form a homogeneous austenitic phase and then cooling the steel into a microstructure of uniformly dispersed dislocated martensite separated by continuous thin boundary films of stabilized retained Austenite.
Abstract: A high strength, tough alloy steel, particularly suitable for the mining industry, is formed by heating the steel to a temperature in the austenite range (1000°-1100° C.) to form a homogeneous austenite phase and then cooling the steel to form a microstructure of uniformly dispersed dislocated martensite separated by continuous thin boundary films of stabilized retained austenite. The steel includes 0.2-0.35 weight % carbon, at least 1% and preferably 3-4.5% chromium, and at least one other subsitutional alloying element, preferably manganese or nickel. The austenite film is stable to subsequent heat treatment as by tempering (below 300° C.) and reforms to a stable film after austenite grain refinement.

40 citations




Journal ArticleDOI
TL;DR: In this paper, the solidification structure of rapidly quenched commercial high speed tool steels has been studied by means of two-piston splat-quenching and argon-arc plasma-spraying.
Abstract: The solidification structure of rapidly quenched commercial high speed tool steels has been studied by means of two-piston splat-quenching and argon-arc plasma-spraying. X-ray studies of the as-quenched structure reveals an increase in austenite retention and almost complete suppression of carbide formation. After tempering, splat-quenched and plasma-sprayed specimens show a hardening peak at higher temperatures and higher hardness than the same steels heat-treated conventionally. X-ray diffraction work reveals that on tempering, austenite transforms to a bcc phase, with the austenite disappearing by 700°C, and no detectable carbide precipitation.

Journal ArticleDOI
TL;DR: In this paper, the authors showed that increasing the purity of Fe−Mn alloys raises the initial temperature of the γ→β transformation, as the result of which a larger quantity of martensite is formed.
Abstract: 1. Increasing the purity of Fe−Mn alloys raises the initial temperature of the γ→ɛ transformation, as the result of which a larger quantity of ɛ martensite is formed. The maximum quantity of ɛ martensite (85%) is formed with quenching from 1100° in the alloy of high purity containing 17% Mn. 2. Heat treatment (different cooling conditions in quenching, cold treatment, tempering) has only a slight effect on the quantity of ɛ phase formed. Most of the ɛ martensite is formed during quenching, and it can be considered that the Fe−Mn alloys investigated are insensitive to heat treatment.

Patent
26 Oct 1978
TL;DR: In this paper, a process for the thermal treatment of thin products made of 7000 series aluminum alloys comprising a solution heat treatment, quenching treatment and a tempering treatment in three stages is described.
Abstract: A process for the thermal treatment of thin products made of 7000 series aluminum alloys comprising a solution heat treatment, quenching treatment and a tempering treatment in three stages: pretempering between 100° and 150° C. for 5 minutes to 24 hours; intermediate tempering; and, final tempering between 100° and 160° C. for 2 to 48 hours. Intermediate tempering comprises a rapid rise in temperature to 190° C. followed by a treatment at a temperature θ(t) between 190° and 250° C. for a total duration T in such a way that the function: ##EQU1## is comprised between 0.5 and 1.5; and T and t being expressed in seconds and θ(t) in °K. This tempering treatment imparts to the products treated both high mechanical characteristics and a high resistance to stress corrosion.

Patent
06 Feb 1978
TL;DR: In this paper, the method of manufacturing coiled springs from hot-rolled steel rods is described, wherein round steel rods are formed by hot rolling with the gauge of the rod within a tolerance of ± 0.010 inch and the rod not out of round more than a maximum of 0.015 inch, oil tempering the rod as produced in the hot rolling operation, by passing it through an austenitizing step, an oil quenching step and a tempering step, and winding springs from the oil tempered rod.
Abstract: The method of manufacturing coiled springs from hot-rolled steel rod (as distinguished from drawn wire) wherein round steel rod is formed by hot rolling with the gauge of the rod within a tolerance of ±0.010 inch and the rod not out of round more than a maximum of 0.015 inch, oil tempering the rod as produced in the hot rolling operation, without drawing it, by passing it through an austenitizing step, an oil quenching step and a tempering step, and winding springs from the oil tempered rod.


Patent
30 Nov 1978
TL;DR: In this paper, a steel plate is fabricated to a specified thickness by hot rolling with screwing down at the draft of more than 50% at above Ar3 point and then tempered at a temperature of below Ac1 point.
Abstract: PURPOSE:To stabilize the strength and toughness, by directly hardening and tempering in the cooling process after hot rolling of steel plate. CONSTITUTION:A steel slab containing C by 0.01-0.25%, Si by 0.005-1.00%, Mn by 0.10-3.0%, Al by 0.005-0.15%, P by <0.03%, and S by <0.03%, and one or two or more kinds of Ni <10%, Cu <1%, Cr <2%, Mo <1%, V <0.2%, Nb <0.2%, and B <0.01% is produced by hot rolling. In the cooling process, this slab is heated to a temperature region of 1050-1300 deg.C to prevent coarsening of the austenite, while precipitates such as carbides and nitrides are turned to solid solution. Then, the steel plate is fabricated to a specified thickness by hot rolling with screwing down at the draft of more than 50% at above Ar3 point. The equal temperature is maintained for 1-15 minutes until Ar3 transformation starts, and after cooling process, the steel plate is quench-hardened to less than 200 deg.C, then tempered at a temperature of below Ac1 point. Thus, steel plates of which strength and toughness are excellent and stable, having uniform properties may be produced.

Journal ArticleDOI
TL;DR: In this paper, the variation in composition of carbides formed during the tempering at 700°C of complex medium-carbon steels containing tungsten or molybdenum has been followed by analytical electron microscopy.
Abstract: The variation in composition of carbides formed during the tempering at 700°C of complex medium-carbon steels containing tungsten or molybdenum has been followed by analytical electron microscopy. Quantitative analysis of carbides containing tungsten has been achieved using L α X-ray intensity measurements. Direct measurement of carbide compositions has meant that chemical as well as structural observations can be made during the tempering of alloy steels.

Book ChapterDOI
01 Jan 1978
TL;DR: In this paper, the authors present results of toughness measurements and fractographic observations made on a quenched and tempered 0.6% carbon steel and use these as a basis for a discussion of the factors affecting "623K (350 °C) embrittlement" (one-step temper embrittlements).
Abstract: The aim of this paper is to present results of toughness measurements and fractographic observations made on a quenched and tempered 0. 6%, carbon steel and to use these as a basis for a discussion of the factors affecting "623K (350 °C) embrittlement" (one-step temper embrittlement).

Journal ArticleDOI
TL;DR: In this article, a modified Hopkinson bar was used to compress steel specimens of type 1023 and heat treated 4130 steel of hardnesses, between 257 and 450 HV10, at strain rates between 3 × 10 3 and 3× 10 4 s −1 using a modified Johnsonson bar.

Patent
15 May 1978
TL;DR: In this paper, a secondary hardening alloy steel composition consisting essentially of about 0.25-0.5% carbon, 0.5-1.0% manganese, about 1.5 -3.0%, the balance being iron and impurity elements is presented.
Abstract: A secondary hardening alloy steel composition consisting essentially of about 0.25-0.5% carbon, about 0.5-1.0% manganese, about 1.5-3.0% nickel, about 0-1.0% chromium, about 1.75-2.5% molybdenum, about 0-0.4% vanadium, and an additive selected from about 1-3% aluminum and a combination of at least about 1% aluminum and at least about 1% silicon for a combined Al+Si content of about 2-4%, the balance being iron and impurity elements. The present steel composition has the following characteristics: it exhibits a flat tempering response, it is hardenable upon tempering to a Rockwell C hardness of at least 50, and it has an improved combination of hardness vs. toughness properties after tempering in the secondary hardening range. A method of preparation is also described.

Patent
20 Nov 1978
TL;DR: In this paper, a solution heat treatment, quenching and tempering process for a relatively thick product made of a copper-containing aluminum alloy of the 7000 series is described.
Abstract: A process for the thermal treatment of a relatively thick product made of a copper-containing aluminum alloy of the 7000 series, the invention involving a solution heat treatment, quenching and tempering in three steps: (1) preliminary tempering at between 100° and 150° C. for five minutes to 24 hours; (2) intermediate tempering; and, (3) final tempering for 2 to 48 hours at between 100° and 160° C. The intermediate tempering step comprises a rapid rise in temperature in the zone at 150° to 190° C. followed by an evolution θ(t) above 190° C. for a period T, such that: ##EQU1## is between 1 and 4, K=1.5 except for certain alloys where K=3. T and t are expressed in seconds, θ(t) is expressed in °K. and is between 463° and 523° K. The present process provides increased mechanical strength to the product as well as a high resistance to stress corrosion.

Journal ArticleDOI
TL;DR: In this paper, a survey of production rotors has been made in order to define the variation of toughness with both position and direction, and the inherent toughness of the upper bainite was less than that of the lower-bainite-martensite, the difference being equivalent to some 50°C fracture appearance transition temperature.
Abstract: In order to guarantee the integrity of large monobloc 3·5Ni-Cr-Mo-V rotor forgings, a comprehensive knowledge of their toughness is required. Experimenta heat treatments have been used to define the inherent toughness behaviour of the steel, and a survey of production rotors has been made in order to define the variation of toughness with both position and direction. The lower bainite-martensite structure of the rim and the upper bainite of the core had identical strength and ductility tempering characteristics. The inherent toughness of the upper bainite was less than that of the lower bainite-martensite, the difference being equivalent to some 50°C fracture appearance transition temperature (FATT). However, the difference between the two was much reduced by temper embrittlement, since the rim martensite embrittled more than the core bainite. Toughness was insensitive to strength up to 800 N/mm2 proof strength, the unembrittled toughness (FATT) being −100°C (rim) and −60°C (core) at this strengt...

Journal ArticleDOI
TL;DR: In this paper, the initiation and growth of cracks at 565 °C have been studied in a sample of 2 1 4 Cr-1Mo weld metal deposited by the manual arc process and it was found that, whereas tempering treatments at both temperatures were beneficial relative to the as-welded condition, prestrain introduced by stress relaxation at 650 °C produced marked embrittlement.


Patent
Yamada Senichi1, Yoshio Kato1
28 Jun 1978
TL;DR: In this paper, the authors describe a uni-directional lamellar structure of tough martensite in a uniform austenite matrix, which is then hardened by tempering.
Abstract: Heat-treated steel of particular, but known, composition is quenched, worked in one direction and then hardened by tempering to form a uni-directional lamellar structure of tough martensite in a uniform austenite matrix.

Journal ArticleDOI
TL;DR: In this paper, a suitable testing technique is developed for evaluating the effect of weld residual stress on fracture toughness in the HAZ region of a reactor pressure vessel steel (SA533 Grade B, Class 1) and for investigating its susceptibility to reheat and underclad cracking or local embrittlement in the coarse-grained HAZs during post weld heat treatment.

Patent
10 Feb 1978
TL;DR: In this article, a heat resistant low-alloyed steel casting which is suitable for the casing material of a steam turbine is presented, where the steel casting is heated to 230 to 460°C or 670 to 780°C at which carbides crystallize out, and then subjected to a more than one repeated homogenizing and tempering treatment in order to convert all constitution into the fine structure of bainite or bainsite or Bainite and ferrite.
Abstract: PURPOSE: To raise the strength of low alloy steel casting at high temperatures as well as minimize the developing rate of creep cracks by the procedure in which a Cr-Mo-V low alloy steel casting is heated in the temperature range where carbide crystallizes out, and then subjected to a more than one repeated homogenizing and tempering treatment. CONSTITUTION: The heat resistant low alloy steel casting contains 0.05 to 0.40% C; < 1.5% Si, < 3.0% Mn, 0.5 to 3.0% Cr, 0.5 to 3.0% Mo, and 0.10 to 0.20% V, together, as needed, with <0.50% Ni or 0.005 to 0.10% at least one of Ti, Al, Zr, Nb, and Ta, which serve to improve toughness and also to make finer crystal granules. The steel casting is heated to 230 to 460°C or 670 to 780°C at which carbides crystallize out, and then subjected to a more than one repeated homogenizing and tempering treatment in order to convert all constitution into the fine structure of bainite or bainite and ferrite. Thus, a heat resistant low alloy steel casting which is excellent in high temperature strength and also small in the developing rate of creep cracks can be obtained, which is suitable for the casing material of steam turbine. COPYRIGHT: (C)1979,JPO&Japio

Book ChapterDOI
TL;DR: In this paper, four high-strength marine alloys, including HY-130 steel, 17-4 PH steel, Ti-6Al-2Cb01Ta-0.8Mo, and 5456-H116 aluminum, were evaluated under the conditions of corrosion fatigue.
Abstract: : Fatigue crack propagation was studied on samples of four high-strength marine alloys to determine the sensitivity of fatigue-crack growth rates to seawater and electrochemical potential. The materials studied included HY-130 steel, 17-4 PH steel in several combinations of melt processing and temper, Ti-6Al-2Cb01Ta-0.8Mo, and 5456-H116 aluminum. Fatigue testing was conducted at low cyclic frequency, and the fatigue data are presented in terms of fatigue-crack growth rate (da/dN) versus crack-tip stress-intensity factor range (Delta K). Test specimens were exposed to fresh flowing natural seawater under freely corroding and potentiostat-controlled electrochemical conditions while undergoing corrosion-fatigue-testing. The results of this investigation reveal significantly distinct differences among the four alloys under the conditions of corrosion fatigue. Both seawater and potential acted to accelerate crack growth rates in the ferrous alloys, which proved to be much more sensitive to seawater and negative potential than the nonferrous alloys studied. The titanium alloy exhibited no measurable sensitivity to either seawater or negative potential. The aluminum alloy exhibited only moderate sensitivity to seawater and beneficial effects from both positive and negative potentials. These exploratory studies indicate that high-strength marine alloys exhibit widely differing responses to corrosion-fatigue crack growth and that high-strength steels currently aimed for marine service are among the alloys most deleteriously affected.

Journal ArticleDOI
TL;DR: In this paper, a simple stress-state model of a tempered flat glass specimen was used to predict the transient birefringence in a rectangular glass specimen subjected to uniform and symmetrical heat-transfer conditions, at a temperature where glass behaves as a perfect elastic material with no stress relaxation within the experimental time.
Abstract: Thermal tempering is widely used to manufacture safety glass for economic as well as for certain safety measures. Laboratory investigations of the tempering process and the resultant strengthening effect are generally limited to rectangular specimens. Results are, therefore, appropriate for this particular geometry. This paper describes a simple stress-state model of a tempered flat glass specimen. the model, developed using photoelastic equations to determine the three-dimensional stress components, was used to predict the transient birefringence in a rectangular glass specimen subjected to uniform and symmetrical heat-transfer conditions, at a temperature where glass behaves as a perfect elastic material with no stress relaxation within the experimental time. A method of determining the coefficient of heat-transfer rate was then developed based on the analysis of the transient birefringence. This technique uses the glass specimen as an optical transducer, and does not affect, in any way, the natural flow of heat by forced convection or contact cooling.