317 stainless steel

Stainless steel is well known as being difficult to bond, especially when long-term environmental resistance is required. The degree of difficulty increases with the increasing chromium content of the steel. The oxides associated with low carbon steels are very stable but are thin and very smooth they have none of the micro-roughness which is typical for other substrates. 

The correct pretreatment, therefore, is vital and, amongst other considerations, it will be dependent on the grade of stainless steel being used as well as the minimum specified tensile strength of the substrate and the projected end use of the bonded component. 

It is generally to be recommended that, before attempting to bond stainless steel components, bonding trials should take place to determine the optimum method and conditions needed to obtain the best bond strengths with the particular stainless steel being used. Such trials will also take into account end usage and, particularly, the durability requirements. 

Several pretreatments are recommended by the British Standards Institute [66]. In essence, these methods cover solvent and/or alkaline degreasing followed by surface abrasion or by the use of a chemical etchant. Grit blasting, using chiU-cast iron shot, glass or alumina, is the ideal abrasion technique. Etchants based on sulphuric, hydrochloric or phosphoric acid are recommended etching conditions are 5-30 min at temperatures from ambient to 65°C. 

In many cases, the chemically pretreated substrates will require desmutting after etching and washing. This can be accomplished by immersion in the standard CSA pickling solution (see above) for 5-20 min at 60-65°C. Once such a bath has been used for desmutting stainless steel the pickle cannot be used again for the pretreatment of aluminium. 

Easy cleaning and sanitizing make stainless steel popular in food or biological laboratories. Contact with strong mineral acids, however, will show that it is not quite stainless. An abrasive is required to remove such stains. While resistant, a steel top will temporarily bulge when exposed to heat, which sometimes can interfere with the alignment of equipment set-ups. 

Although there is a great difference in potential between stainless steel and aluminium alloys, in the order of 650 mV, it is unusual to see galvanic corrosion on aluminium in 

Although surface preparation methods are usually different, the adhesives used for mild steel can generally be used for stainless steel. 

Adhesives recommended include casein glue, epoxies, polyvinyl alkyl ether, polyacrylate (carboxylic), SBR, and polyisohutylene. 

The explanation appears to lie in the accumulation of lattice vacancies at the nucleation sites of the helium bubbles. The average energy of a neutron in the fast reactor is above 100 keV, greatly in excess of the 25 eV or so which is required to displace an atom from a lattice site. Neutron collisions, followed by multiple cascade processes, therefore lead to a high density of vacancies and interstitials. The interstitials have a higher mobility than the vacancies and tend to be more rapidly absorbed at grain boundaries and dislocations, where they lose their identity. The surplus vacancies are then available for the formation of voids at the nucleation centers of the helium produced by the (n, a) reactions. 

It should be noted that irradiation of steels in thermal reactors also produces embrittlement, though in this case the main contributor of helium is the (n, a) reaction of slow neutrons with boron impurity in the steel. Because of the high thermal absorption cross section of the boron, however, this burns out at fairly moderate exposures, leading to saturation of the effect. 

This is in contrast to the fast neutron case, where the reaction cross sections are much lower and the helium content increases steadily with increasing fluence. 

Remove the black residue formed on the metal with a clean, stiff brush while holding the metal under cold, running distilled or deionized water 

Dry the metal by heating at 120°C for 1 h. If the steel part cannot be stored immediately in an area of low humidity (less than 30% RH) apply the adhesive immediately after cleaning  

This is a surface treatment process based on the oxidation of the steel to produce a continuous epsilon oxide (Fc203). It is reported to give strong durable bonds and to improve the salt-spray and humidity resistance of polymer-coated steel. The steps are 

Alkaline clean in a solution containing 3% trisodium phosphate and 3% sodium carbonate for 5 min at 82 °C 

ASTM D2651-01 lists the following mechanical and chemical methods for surface preparation of carbon steel. 

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Stainless steel. A group of Cr or Cr —Ni steels showing an unusually high resistance to corrosion by the atmosphere and many chemical reagents. In order to achieve this resistance to corrosion > 12% Cr is necessary. 

CO2 corrosion often occurs at points where there is turbulent flow, such as In production tubing, piping and separators. The problem can be reduced it there is little or no water present. The initial rates of corrosion are generally independent of the type of carbon steel, and chrome alloy steels or duplex stainless steels (chrome and nickel alloy) are required to reduce the rate of corrosion. 

Two types of materials are studied in the CIAPES programme ferritic steel and stainless steel. A database for vessels monitored by acoustic emission has been builded to collect the results of all the tests carried out in laboratory and in situ. 

Main steamline section and weld of the same Unit 4 f600 MW3 as above the weld connects 2 steamline sections of different materials (stainless steel and low-alloy steel) through a transition material section, ahead of the Y-piece where branching of the turbine inlet lines takes place (255 mm internal diameter, 44.5 mm thickness). Ultrasonic inspection pointed out potential integrity problems in the weld. The requirement was again that AE could support safe operation of the weld until the next incoming planned maintenance shutdown. 

Waveguides 4 waveguides (points 5L-8L,. I), made of AISI 304 stainless steel, L = variable, (j>=6 mm, have been installed on the lower body of the SH header of unit 3 and 8 waveguides (points 2A-5A and points 2P-5P,y5. 2), made of AISI 304 stainless steel, L = 3240 mm, if>=6 mm, have been installed on the front (4 waveguides) and rear (4 waveguides) bodies of the SH header of unit 4. 

AE activity recorded on the SH header of Unit 3 is substantially lower than that recorded the SH header of Unit 4 this could be traced to the different materials of the 2 headers (stainless steel vs low alloy steel). 

The technique presented above has been extensively evaluated experimentally using ultrasonic data acquired from a test block made of cast stainless steel with cotirse material structure. Here we briefly present selected results obtained using two pressure wave transducers, with refraction angles of 45° and 0°. The -lOdB frequency ranges of the transducers were 1.4-2.8 MHz and 0.7-1.4 MHz, respectively. The ultrasonic response signals were sampled at a rate of 40 MHz, with a resolution of 8 bits, prior to computer processing. 

Cryogenics We use several types of evacuated stainless steel cryostats of about 1 htre capacity to provide the 77 K cooling with hquid nitrogen. The simplest, best valued and easiest to handle one is a ordinary thermos flask available from the supermarket (see fig.3). It is sufficient for a measurement period of more than 12 hours. A specially designed stainless steel vessel gains cooling periods of 30 hours. 

Heightened wear resistance of the pickup working surface thanks to the use of a protective plate of stainless steel. 

Figure 8 Sensitivity of the new photothermal camera to small depth defects. lmage of an EDM notch of 1mm long, 100 pm width and 200 pm depth on ANSI 304 stainless steel with a bad surface condition (ground surface, "Vi 2 -6 ).

The sensitivity curves are plots of maximum achieved sensitivity as a function of thickness of the object for a given focal spot size and source to detector distance. The best attainable sensitivity in image intensifier systems is a function of tube voltage, current, scattered radiation and the screen gamma. As a first step, stainless steel plates with thicknesses ranging from 5 mm-30 mm in steps of 5 mm were chosen. These plates had a length of 950 mm and width of 280 mm. The plate is positioned very close and at the center to the LI. tube. The extraneous... 

Heat conductivity of ceramic equals the conductivity of stainless steel. Cooling through the ceramic is possible to certain limits. 

Application of ceramics allows using stainless steel as vacuum envelope. No surface charges ean deflect the electron beam. Mechanical elements and functions can be easily integrated into the envelope due to its stability. 

When a block is inside, the entrance panel is closed and the inspection is ready to start. The inside of the stainless steel X-ray tubehead housing is clad in lead with an on/ofT shutter in front of a thin plastic X-ray window. The thin window is to ensure the IP 65 classification. The window is of plastic that is not affected by the cleaning agents. The on/off shutter is interlocked with the entrance and exit panels so X-rays can be kept on at all times without risk of radiation leakage or exposure of the frozen fish blocks prior to the actual inspection. 

All metal parts exposed to the room are made of stainless steel and motors and transmissions are IP 65 to withstand the eflfect of the cleaning agents. The design also takes into account the special considerations necessary for food processing machinery with regards to easy accessibility to all parts and the lack of corners, edges, pockets or other food traps , so that the mechanical system can be easily cleaned. 

Prompted by the success, TOFD measurements were conducted on a fatigue crack in a stainless steel compact tension specimen. Test and system parameters were optimised following the same procedure used for carbon steel specimens. A clear diffracted signal was observed with relatively good SNR and its depth as measured from the time-of-flight measurements matched exactly with the actual depth. 

Considering the success of detecting crack tip echoes from defects at the near probe surface, future work will deal with the detection and sizing of defects on the far probe surface. Future work also relates to carrying out defect sizing in anisotropic austenitic stainless steel welds and... 

This study detects the defect of the void and the exfoliation in the solid phase diffusion bonding interface of ductile cast iron and stainless steel with a nickel insert metal using ultrrasonic testing method, and examine the influence of mutual interference of the reflectional wave both the defect and the interface. 

The materials are austenitic stainless steel (Hereafter,it is said SUS304), ductile cast iron (Hereafter, it is said FCD500), and pure Ni. The composition of the materials is shown in Table. 1. Moreover, the sound characteristic of the materials and air as the defect are shown in Table.2. 

Fig. ni-19. Trough for dynamic surface measurements A, stainless-steel dish B, aluminum mantle C, inlet thermostatting water D, lower PTFE bars E, oscillating bars F, attachment lower bars G, Wilhelmy plate. (From Ref. 140.)... 

The adhesion between two solid particles has been treated. In addition to van der Waals forces, there can be an important electrostatic contribution due to charging of the particles on separation [76]. The adhesion of hematite particles to stainless steel in aqueous media increased with increasing ionic strength, contrary to intuition for like-charged surfaces, but explainable in terms of electrical double-layer theory [77,78]. Hematite particles appear to form physical bonds with glass surfaces and chemical bonds when adhering to gelatin [79]. 

Modem UHV chambers are constmcted from stainless steel. The principal seals are metal-on-metal, thus the use of greases is avoided. A combination of pumps is nomially used, including ion pumps, turbomolecular pumps, cryopumps and mechanical (roughing) pumps. The entire system is generally heatable to 500 K. This bakeout for a period of... 

Figure Bl.27.4. Rotating bomb isoperibole calorimeter. A, stainless steel bomb, platinum lined B, heater C, thermostat can D, thennostat iimer wall E, themiostat water G, sleeve for temperature sensor H, motor for bomb rotation J, motor for calorimeter stirrer K, coimection to cooling or heating unit for thennostat L, circulation pump.

Figure Bl.27.7. Schematic diagram of isothennal displacement calorimeter A, glass calorimeter cell B, sealed heater C, stainless steel stirrer D, thennistor E, inlet tube F, valve G, window shutters Ft, silver rod ...

In tenns of an electrochemical treatment, passivation of a surface represents a significant deviation from ideal electrode behaviour. As mentioned above, for a metal immersed in an electrolyte, the conditions can be such as predicted by the Pourbaix diagram that fonnation of a second-phase film—usually an insoluble surface oxide film—is favoured compared with dissolution (solvation) of the oxidized anion. Depending on the quality of the oxide film, the fonnation of a surface layer can retard further dissolution and virtually stop it after some time. Such surface layers are called passive films. This type of film provides the comparably high chemical stability of many important constmction materials such as aluminium or stainless steels. 

Pitting occurs witli many metals in halide containing solutions. Typical examples of metallic materials prone to pitting corrosion are Fe, stainless steels and Al. The process is autocatalytic, i.e., by initial dissolution, conditions are established which furtlier stimulate dissolution inside tire pit tire metal (Fe in tire example of figure C2.8.6 dissolves. 

On a laboratory scale, hydrotliennal syntliesis is usually carried out in Teflon-coated, stainless-steel autoclaves under autogenous pressure. A typical syntliesis mixture consists of up to four major constituents, a T-atoni source (silicon and aluminium, otlier elements may also be incoriiorated as indicated above), a solvent (almost exclusively... 

Nickel is a moderately lustrous, silvery metal, and is extensively used in alloys (for example coinage, stainless steel) and for plating where a durable resistant surface is required. It is also used as an industrial catalyst, for example in the hydrogenation of unsaturated organic compounds. It is attacked by dilute aqueous acids but not by alkalis it combines readily with many non-metals on heating. 

Heat a small portion of the following substances on an inverted porcelain or stainless steel crucible lid. At first, heat one side of the lid gently so that the heat travels along the lid to the organic substance later heat the lid more strongly. Note carefully in particular [a) the change in appearance, (b) whether readily inflammable, (r) any odour produced, (d) wliether a non-volatile residue is left. 

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