Simultaneous Heat Treatment Research Articles

Vacuum Brazing of 18MAR300 Nickel Maraging Steel Joints Based on Additively Manufactured and Conventional Material Grades

Laser powder bed fusion (LPBF) processes offer the best possible design options for the production of highly complex components with unique functionalities. Although the development of additive manufacturing processes is progressing impressively and build rates have already been significantly increased, the economic production of high‐volume components is still particularly truncated. Comparatively expensive powders, machine‐hour rates, and a limited construction space demonstrate a high demand for joining LPBF components to conventionally manufactured parts. Vacuum brazing is an excellent technology for manufacturing and simultaneous heat treatment of such hybrid components. The aim of this study is to investigate the brazeability and the joint properties of ultrahigh‐strength nickel maraging steel 18MAR300 (1.2709, X3NiCoMoTi18‐9‐5) using BVAg‐30 (Ag68Cu27Pd5) as brazing filler metal. For this purpose, the effect of nickel‐plated surfaces on the wettability and the microstructure of the joint is studied for conv./conv.‐, LPBF/conv.‐, and LPBF/LPBF joints. Furthermore, the quasi‐static and quasi‐dynamic joint strength is evaluated. The results prove that nickel‐plated surfaces are vital to achieve a sufficient process control. The coating assures a deoxidized and sealed surface which favors the formation of NiCu(Fe,Pd,Ag) phases within the braze metal thus enhancing the joint strength. In addition, LPBF/LPBF joint features have significantly higher tensile strength than conv./conv. joints (825–627 MPa).

Control-Oriented Characterization of Product Properties during Hot Hole-Flanging of X46Cr13 Sheet Material in a Progressive-Die

Robust and versatile production is enabled by a closed-loop control of product properties. This essentially relies on the characterization of the interaction between properties and available degrees of freedom to control the process. In particular, this work examines the setting of collar height, thinning, curvature, and hardness during hot hole-flanging of X46Cr13 sheet material with simultaneous heat treatment to identify approaches for a closed-loop property control in hot hole-flanging during multi-stage hot sheet metal forming. To scrutinize the adjustability of the hardness of X46Cr13 sheet material by heat treatment with rapid heating and short dwell times, quenching tests with austenitizing temperatures from 900 to 1100 °C and dwell times from 1 to 300 s were carried out. A hardness between 317 and 680 HV10 was measured. By analyzing the force-displacement curve and the contact situation between tools and blank during hot hole-flanging, an understanding for the process was established. To determine the adjustability of geometrical collar properties and the hardness of the collar, collars were formed at punch speeds between 5 and 100 mm/s and at different temperatures. Here, a dependency of the geometry of the collar on temperature and punch speed as well as setting of the hardness was demonstrated.

A thermo-mechanical machining method for improving the accuracy and stability of the geometric shape of long low-rigidity shafts

The article presents a new thermo-mechanical machining method for the manufacture of long low-rigidity shafts which combines straightening and heat treatment operations. A fixture for thermo-mechanical treatment of long low-rigidity shafts was designed and used in tests which involved axial straightening of shafts combined with a quenching operation (performed to increase the corrosion resistance of the steel used as stock material). The study showed that an analysis of the initial deflections of semi-finished shafts of different dimensions and determination of the maximum corrective deflection in the device could be used as a basis for performing axial straightening of shaft workpieces with simultaneous heat treatment and correction of the initial deflection of the workpiece. The deflection is corrected by stretching the fibers of the stock material, at any cross-section of the shaft, up to the yield point and generating residual stresses symmetrical to the axis of the workpiece. These processes allow to increase the accuracy and stability of the geometric shape of the shaft.

Development of Energy Saving Technologies for Steel Wire Heat Treatment

This article presents the development of energy-saving induction heating technology to accelerate significantly the process of heat treatment of steel wire. The analysis of international trends and prospects of the use of induction heating shows a steady expansion of the applied induction technologies in metallurgy. The article considers the advantages of induction heating in comparison with other competitive technologies. Heat treatment in electro-technical induction units is determined by the interrelated electrical and thermal processes in them, the complex nature of the distribution of internal heat sources, the dependence of the nature of the power distribution of the induction unit on the temperature of the products processed. The features of the applicated in the induction method of heating in the hardware industry for objects previously unused: such as coils of wire and riots of calibrated steel. The results of the study show the influence of the induction method of heating on temperature-time factors to the formation of the structure, to increase the uniformity of heating and the quality of heat treatment of steel wire, calibrated steel in riots, taking into account the technological problem. The authors give the assessment of the effectiveness of medium and high-frequency induction heating of steel wire of various diameters. The evaluation of the increase in the efficiency of an induction heating unit with the simultaneous heat treatment of several filaments of steel wire of the same diameter, combined into a bundle, was made.

An Alkali-Metal Ion Extracted Layered Compound as a Template for a Metastable Phase Synthesis in a Low-Temperature Solid-State Reaction: Preparation of Brookite from K0.8Ti1.73Li0.27O4

We have designed a new approach to synthesize brookite, i.e., to extract alkali-metal ions from K(0.8)Ti(1.73)Li(0.27)O(4) (KTLO) and to apply simultaneous heat treatment to the remaining lepidocrocite-type layers of TiO(6) octahedra. For the alkali-metal ion extraction and the simultaneous heat treatment, KTLO was heated at 400 degrees C with polytetrafluoroethylene (PTFE) in flowing Ar. PTFE has been found to be an effective agent to extract strongly electropositive alkali-metal ions from KTLO because of the strong electronegativity of F as its component. The product of this reaction consists of a mixture of brookite, K(2)CO(3), LiF, and PTFE derivatives, indicating the complete extraction of K(+) and Li(+) from KTLO and formation of brookite from the lepidocrocite-type layer of TiO(6) octahedra as a template. This brookite has a partial replacement of O(2-) with F(-) and/or slight oxygen deficiency; thus, its color is light-bluish gray. Fully oxidized brookite formation and complete decomposition of PTFE derivatives have been achieved by further heating in flowing air, and coproduced alkali-metal salts have been removed by washing in water. Powder X-ray diffraction, Raman spectroscopy, and chemical analysis results have confirmed that the final brookite product treated at 600 degrees C is single phase, and it is white. The method to extract alkali-metal ions from a crystalline material using PTFE is drastically different from the common methods such as soft-chemical and electrochemical reactions. It is likely that this new synthetic approach is applicable to other layered systems to prepare a diverse family of compounds, including novel metastable ones.

A new cell line from the embryonic tissue of Helicoverpa armigera HBN. (Lepidoptera: Noctuidae).

A new cell line from the embryonic tissue of Helicoverpa armigera was established and designated as NIV-HA-197. It was maintained in TNM-FH medium supplemented with 10% fetal bovine serum. The cell line at passage 20 had a heterogeneous population of cells consisting of mainly epithelial-like cells (70%), followed by fibroblast-like (27%), and multinucleated giant (3%) cells. The chromosome number ranged from 45 to 185. The growth curve at passage 40 showed a fivefold increase in cell number with a population-doubling time of approximately 60 h. The cell line was found infected with the microsporidium Nosema heliothids at passage 9. Using the antiprotozoan drug Metrogyl 400 and simultaneous heat treatment, the parasite was removed from the culture. The cell line can be cryopreserved for 30 mo. The species specificity of the new cell line was determined by studying the isoenzyme profile of four enzymes, viz., lactate dehydrogenase, malate dehydrogenase, isocitrate dehydrogenase, and glucose 6-phosphate dehydrogenase, and by heteroduplex analysis. Heteroduplex analysis was used to analyze the mitochondrial 16S ribosomal ribonucleic acid gene sequences along with the host insect gene sequences, and 100% homology was obtained, confirming the conspecificity of the cell line. The cell line was found to be susceptible to the baculoviruses Autographa californica multiple nucleopolyhedrovirus, Spodoptera litura multiple nucleopolyhedrovirus, and H. armigera single nucleopolyhedrovirus (HaSNPV). More than 90% of the cells were infected by HaSNPV on the seventh post infection day (PID), and 28.8 x 10(6) NPV/ml was yielded on the 10th PID. The in vitro-grown HaSNPV caused 100% mortality, when fed to the second instar H. armigera larvae, in 6 d. Cessation of feeding was observed on the second PID.

Shape memory effect of cable-in-conduit conductors

In fusion magnets, cable-in-conduit conductors (CICCs) are foreseen, consisting of an outer conduit and an inner niobium-tin cable produced by a simultaneous heat treatment. The heat treatment and the different thermal contractions of the various conductor materials lead to prestress onto the niobium-tin filaments during cool down, degrading the superconducting parameters considerably. These parameters show, during external mechanical loading, a maximum dependence on strain (E). For example, the critical current (I/sub c/) of steel jacketed CICCs increases by about a factor of 2 at /spl epsi//spl ap/0.7% and decreases again at further straining (B=13 T, T=4 K). This characteristic is reversible up to /spl epsi//spl ap/1.2% in stressed and unstressed condition of the conductor. If the conductor is plastically deformed at 4 K up to a remaining strain (/spl epsi//sub r/) and then warmed up to 295 K, /spl epsi//sub r/, decreases by about a factor of 5, which is coupled to a phase transition resulting in a change of volume in the microstructure of the steel conduit. This reduced /spl epsi//sub r/ remains constant after cooling to 4 K again (shape memory) and the critical current corresponds to this decreased /spl epsi//sub r/. In case of an accidental over-straining of a CICC, a further temperature cycle of 4 K/spl rarr/295 K/spl rarr/4 K would recover I/sub c/. Recovery strain results with different jacket materials (aged) of Type 316L, 316LN, Incoloy 908, and titanium are investigated.

Optimising the recovery of recombinant thermostable proteins expressed in mesophilic hosts

The purification of a thermostable Caldocellum saccharolyticum β-glucosidase expressed in Escherichia coli was investigated using heat precipitation of unclarified cell homogenates. Heat treatment at 70 °C was capable of purification with respect to cell debris, small particulates and the majority of cell protein, although E. coli proteins were even more efficiently removed at 80 °C and above. For thermostable proteins expressed in E. coli, a precipitation temperature of 80 °C or greater is recommended for optimal removal of contaminant proteins. In small-scale heating trials, heating rate was found to influence enzyme yield significantly. Losses were minimised when ‘flash-heating’ was employed. The successful single-step removal of particulates, labile protein and nucleic acids was achieved by simultaneous heat-treatment and polyethyleneimine addition, although the purification achieved was additive rather than synergistic.

High-gain SOI polysilicon emitter transistors

The authors report the first high-gain polysilicon emitter bipolar transistors fabricated on zone-melting-recrystallized (ZMR) silicon-on-insulator (SOI) material. Current gains as high as 230 were obtained. Polysilicon emitter bipolar transistors made on bulk silicon wafers with identical and simultaneous heat treatments show significant differences in emitter resistance and DC characteristics as compared with SOI bipolar transistors. Post-metal anneal improves the current gain and base current ideality at low base-emitter voltages for both types of wafers. >

Effects ofcis-diamminedichloroplatinum (CDDP) andcis-diammine (1,1-cyclobutanedicarboxylate) platinum (CBDCA) on thermotolerance development and thermosensitivity of the thermotolerant cells

The interactive effects of combined treatment with heat and CDDP (0.5 micrograms/ml) or CBDCA (10 micrograms/ml) were examined on the surviving fractions of V-79 cells. Both CDDP and CBDCA treatment induced a slight enhancement in thermosensitivity of thermotolerant cells. The development of thermotolerance during step-up heating was partially inhibited by simultaneous treatment with CDDP or CBDCA throughout the heating process. Simultaneous heat treatment at 42 degrees C with either drug showed marked interactive effect and inhibited the thermotolerance developed during 42 degrees C heating.

Immunological Study on the Structural Difference between Ribulose- 1,5-bisphosphate Carboxylase/Oxygenase from Nicotiana tabacum var. John William's Broadleaf and the Tobacco Mutant Su/su

Abstract In the present paper we have attempted to characterize by means of immunological methods the molecular difference between ribulose 1,5-bisphosphate carboxylase/oxygenase from the wild type TV. tabacum var. John William's Broadleaf and the tobacco mutant Su/su. The tobacco mutant Su/su exhibits in comparison to the wild type a higher photorespiratory activity. The reagents used in the present study are monospecific antisera to the two bifunctional enzymes to be compared. We have analyzed the oxygenase activity of the two enzymes in dependance on the binding of the amount of antibodies out of the homologous and the not homologous antiserum. These analyses have shown, that the enzymes of both phenotypes were 4 0 % stronger inhibited in the equivalence regions with respect to their oxygenase function by antibodies of the antiserum to ribulose 1,5-bisphosphate carboxylase/oxygenase of the mutant than by antibodies of the wild type antiserum. It should be noted that the antiserum to the mutant enzyme exhibits a 25 % lower antibody titer, than the antiserum to the wild type enzyme. In the region of extreme antibody excess, i.e. when antibodies are mostly monovalently bound and most antigenic determinants are saturated with antibodies, the oxygenase activity of both enzymes decreases towards zero in the presence of the homologous as well as in the presence of non-homologous antibodies. In the region of excess of antigenic determinants, that is when only a few antibody molecules can bind onto the enzymes, only the oxygenase activity of the mutant enzyme is inhibited by its homologous antibodies by 40 % . This apparent difference in the molecular structure of the two bifunctional enzymes to be compared is neither caught in the double immuno diffussion test nor in the tandem crossed immuno electrophoresis, using the two antisera as test reagents. In all cases only fused precipitation bands are observed. Chemical modification of ribulose 1,5-bisphosphate carboxylase/oxygenase by hydroxylamine treatment or treatment with o-(p-nitrophenyl)hydroxylamine or simple heating of the enzyme to 50 °C are immunologically characterized. As a consequence of such treatment considerably less antibodies are adsorbed. The strongest influence exerts a treatment with o-(p-nitrophenyl)-hydroxylamine with simultaneous heat treatment of the enzyme for 20 min at 50 °C.

Modulation of adriamycin transport by hyperthermia as measured by fluorescence-activated cell sorting.

Heat-induced (45.5 degrees C) modification of adriamycin uptake and efflux were measured by flow cytometry in CHO cells in vitro. Administration of adriamycin with simultaneous 15-min or 30-min heat treatment increased drug uptake in a dose-dependent manner. Fluorescence-activated cell sorting showed that cytotoxicity to adriamycin was correlated with relative cellular concentration (fluorescence) for both unheated cells and those heated and simultaneously treated with adriamycin. However, if adriamycin administration followed the heat treatment, accumulation was significantly reduced, primarily as a result of decreased passive drug diffusion (rather than increased efflux) in the heated cells. Cells made heat-tolerant by prior heating also exhibited reduced adriamycin uptake 12 h later, and further heating did not increase uptake. Cell sorting experiments indicated that cytotoxicity of adriamycin was not necessarily correlated with intracellular drug levels when drug administration followed the heat treatment. Also, heat-sterilized cells exhibited a two-fold increase in adriamycin uptake over surviving cells, as assessed by simultaneous measurement of dansyl lysine and adriamycin content. These results indicate that sensitization to adriamycin by simultaneous heat treatment is probably due to increased drug uptake. The decreased sensitization observed when drug administration is followed by heating is probably the result of both decreased uptake and decreased drug DNA accessibility.

Control of threshold voltage of AlGaAs/GaAs 2DEG FET's through heat treatment

Threshold voltage controls of Ni/Ti/Au gate and Ti/Au gate 2DEG AlGaAs/GaAs FET's through only heat treatment are investigated. Ni/Ti/Au gate FET's vary over quite a wide range from a depletion mode to an enhancement mode without degradation of FET characteristics after heat treatment at 300°C. The same experiment is made for Ti/Au gate FET's, but the threshold voltage change is negligibly small. It is confirmed that Ni/Ti/Au can be used as the gate metal for E-FET and Ti/Au as the gate metal for D-FET under simultaneous heat treatment. In addition, a mechanism for penetrating the barrier metal into the underlying layer is discussed.

Metallurgical Factors in Forged and Machined Gear Surface Durability

Forged and machined bevel gears have been tested to compare surface durability for the two manufacturing processes. The tests and results which showed the machined gears to have 30.6 percent more pitted teeth per gear are discussed in a companion paper. This paper assesses the differences in resistance to pitting fatigue based on metallurgical examination. The gears were manufactured to be as nearly identical as possible and they were subjected to simultaneous heat treatment. Differences in depth of hardness, retained austenite, and grain size are considered to be within normal statistical variations of these parameters, although the sample size was small. The strongest evidence indicates the improved pitting resistance of forged gears is due to the random locations of pit initiation sites. Machined surfaces pit in regular patterns along the tool marks. These pits tend to combine by microcracking more rapidly because the pits are more favorably oriented.

Thermomechanical properties of electric brush materials produced from Teflon-lead metallic polymer and graphite powders

Metallic polymer powders have been obtained which can be employed, with various carbon component additions, as starting materials for the production, by hot pressing, of electric brushes. A study was made of the thermomechanical properties of various electric brush materials of this type. The best properties were found to be exhibited by lead + Teflon + graphite metallic polymers produced by simultaneous heat treatment and subsequent hot pressing at 150°C.