Local Heat Treatment

When heat treatment is apphed loeally, a cireumferential band of the run structure, and of the braneh where apphcable, should be heated until the specified temperature range exists over the entire section(s), gradually diminishing beyond the ends of a band that ineludes the weldment or the bent or formed section and at least 25 mm (1 inch) beyond the edges thereof. 

---

Thermally treat the structures to effect a re-solution of the chromium carbide this is often impractical in large structures unless local heat treatment is employed, but is not always satisfactory since a sensitised zone could be produced just outside the local thermally treated region. 

Projectile, Illuminating, Localized Heat Treatment Of Projectile, Illuminating, SIMM, M30ll 2 Metal Parts Assembly... 

A. Merati, K. Sarda, D. Raizenne, and C. Dalle Donne, Improving Corrosion Properties of Friction Stir Welded Aluminum Alloys by Localized Heat Treatment, Friction Stir Welding and Processing II,... 

Homogeneous or localized heat treatment in the temperature range 800-1500°F is prohibited for unstabilized austenitic stainless steel with a carbon content greater than 0.03% used in components of the RCPB. When stainless steel safe ends are required on component nozzles, fabrication... 

The first results of computer-based assessment system application show that the benefits are obvious for repaired (without heat treatment) welds and complex defect configurations defect with height local increasing, group of defects, case analysis of defects interference and possible joining. 

Corrosive chemicals and external exposure can cause tank failure. Materials of construction should be chosen so that they are compatible with the chemicals and exposure involved. Welding reduces the corrosion resistance of many alloys, leading to localized attack at the heat-affected zones. This may be prevented by the use of the proper alloys and weld materials, in some cases combined with annealing heat treatment. 

Dents in tubing can induce erosion failures, especially in soft metals such as copper and brass. Welding and improper heat treatment of stainless steel can lead to localized corrosion or cracking through a change in the microstructure, such as sensitization. Another form of defect is the inadvertent substitution of an improper material. 

The combined effects of a divalent Ca counterion and thermal treatment can be seen from studies of PMMA-based ionomers [16]. In thin films of Ca-salts of this ionomer cast from methylene chloride, and having an ion content of only 0.8 mol%, the only observed deformation was a series of long, localized crazes, similar to those seen in the PMMA homopolymer. When the ionomer samples were subject to an additional heat treatment (8 h at 100°C), the induced crazes were shorter in length and shear deformation zones were present. This behavior implies that the heat treatment enhanced the formation of ionic aggregates and increased the entanglement strand density. The deformation pattern attained is rather similar to that of Na salts having an ion content of about 6 mol% hence, substitution of divalent Ca for monovalent Na permits comparable deformation modes, including some shear, to be obtained at much lower ion contents. 

Marine fouling leading to the local production of HjS increases crack growth rate, but what the effect is when combined with CP is uncertain. Some of the factors mentioned earlier in connection with other steel corrosion problems are important to sulphide stress-corrosion cracking, (SSCC), eg. compositions, particularly C which usefully can be reduced to below 0.05%, S, microstructure and segregation . Compositional homogenisation by heat treatment can be beneficial ", whilst the presence of Cu in the... 

Folliculitis, furuncles, and carbuncles refer to the inflammation of one or more hair follicles, often attributed to infection with S. aureus. Treatment depends on severity and may involve local heat, incision and drainage, and/or oral or topical antibiotic therapy. 

The local heating, and consequent expansion, that occurs during welding can leave the joint in a state of stress. These stresses are relieved by post-welding heat treatment. Not all vessels will be stress relieved. Guidance on the need for post-welding heat treatment is given in the codes and standards, and will depend on the service and conditions, materials of construction, and plate thickness. 

Neto and co-workers examined the ex situ Pt L3 EXAFS for a series of PtRu catalyst powders in air of varying nominal composition from 90 10 through to 60 40 atom %. The catalysts were prepared using a formic acid reduction method developed by the authors which resulted in very poorly alloyed particles, even after heat treatment to 300 °C under a hydrogen atmosphere. Unfortunately, the authors were not able to obtain Ru K edge data to identify the local structure of the Ru in their catalysts. 

Poly[(aniline-2-chloroaniline)-4-toluenesulfonic acid salt] was obtained by oxidative copolymerization of aniline with 2-chloroaniline in solutions containing 4-toluenesulfonic acid. The copolymer salt was subjected to heat treatment under nitrogen atmosphere at elevated (about 150°C) temperatures. The heat-treated samples acquired electric conductivity of 2.7 X 10 f2 cm . According to ESR spectra, the heated poly[(aniline-2-chloroaniline)-4-toluenesulfonic salt] exists as the poly(semiquinone imine ion-radical) in which unpaired electrons are localized on or near the nitrogen atoms (Palaniappan 1997). 

Kooi, E., Vanlierop, J. G. and Appels, J. A. Formation of silicon-nitride at a Si-Si02 interface during local oxidation of silicon and during heat-treatment of oxidized silicon in NH3 gas. Journal of the Electrochemical Society 123, 1117-1120 (1976). 

Energy levels corresponding to electrons localized near the surface may also be present. These are termed surface states. For example, adsorbed ions are one type of surface state they may be of the form of donors, such as hydrogen, which yield electrons to the material, or in the form of acceptors, such as oxygen, which accept, or trap electrons from the material. In Fig. 1, surface traps of the acceptor type are shown, and it is indicated that there are two possible levels present. Other possibilities are impurity atoms at the surface, which are introduced in the preparation of the sample or diffuse from the interior during heat treatment, or nonstoichiometry of the surface layers of the compound. Surface... 

Solid HjPMo o reduced by H2 at a lower temperature shows a very weak ESR signal intensity of Mo5 +, probably because most of the Mo5+ ions are not detectable due to the rapid hopping of electrons. Heat treatment, which eliminates oxide ions from the heteropoly anion, leads to development of the Mo5 + signal, indicating the localization of electrons (101, 102). Early reports of ESR spectra of reduced PMo C o are likely due to these species. Several different species are observed in highly reduced samples. 

---