Carbonates embrittlement

Carbon content is usually about 0.15% but may be higher in bolting steels and hot-work die steels. Molybdenum content is usually between 0.5 and 1.5% it increases creep—mpture strength and prevents temper embrittlement at the higher chromium contents. In the modified steels, siUcon is added to improve oxidation resistance, titanium and vanadium to stabilize the carbides to higher temperatures, and nickel to reduce notch sensitivity. Most of the chromium—molybdenum steels are used in the aimealed or in the normalized and tempered condition some of the modified grades have better properties in the quench and tempered condition. 

Aikaiinity Bicarbonate (HCOs" ), carbonate (COs , and hydroxyl (OH ), expressed as CaCOs Foaming and carryover of solids with steam embrittlement of boiler steel bicarbonate and carbonate produce CO2 in steam, a source of corrosion Lime and lime-soda softening, acid treatment, hydrogen zeolite softening, demineralization, dealkalization by anion exchange, distillation, degasifying... 

Sensitization temperatures (under -320°F). Room temperature embrittlement is nominal. and vessels. stabilized (Types 321,347) and extra low carbon (304 L, 316L) grades. into grain boundaries, with depletion of chromium in contiguous grain boundary areas. austenitic stainless steels. 

Aikaliniry Bicarbonates (HCOd Carbonates (CO,) Hydroxyl (OH) as CaCO, Steam systems foaming and solid carry over Steel embrittlement (HCO,) and (CO,) Corrosion Distillation Demineralization I..ime and lime soda Dealkalization I lon exchange) Acid treatment liydrogcn zeolire... 

Hydrogen at high pressure and temperatures above 4(X) C has a considerable adverse effect on carbon steel, dissolving in the steels and combining with carbides to produce methane and so causing Assuring and considerable embrittlement. However, chromium stabilises the carbides and stainless steel may be safely used in hydrogen at dull red heat ... 

While carburisation itself is not a normal corrosion process, in that there is no metal wastage, absorption and diffusion of carbon can lead to significant changes in the mechanical properties of the affected material and in particular to marked embrittlement. Furthermore, initial carburisation can produce an acceleration of the normal oxidation process, a phenomenon that is notable in nickel-chromium alloys. 

Although the majority of the hydrogen produced on the cathodic areas is evolved as gas and assists the removal of scale, some of it diffuses into the steel in the atomic form and can render it brittle. With hardened or high-carbon steels the brittleness may be so pronounced that cracks appear during pickling. Austenitic steels, however, are not so subject to embrittlement. 

Caustic Embrittlement stress-corrosion cracking of carbon steels caused by the presence of caustic alkali. 

Strength Fibrous minerals Ductility gaining tensile strength. Carbon fibers are more expensive fibrous minerals are least expensive but only slightly reinforcing. Reinforcement makes brittle resins tougher and embrittles tough resins. Fibrous minerals are not commonly used in amorphous resins. 

Caustic cracking (caustic embrittlement) Intergranular corrosion affects both carbon steels and austenitic steels and accelerated by high stress, higher temperatures, and impurities in grain boundaries. 

Boiler compound formulations containing aluminate, silicate, and carbonate ingredients have commonly utilized various ratios of some or all of these constituents, together with caustic soda (for alkalinity control), sodium nitrate or sulfate (to prevent caustic embrittlement), sodium lig-nosulfonate (sludge conditioner), and other compounds. 

The function of the carbon coating is to contain the byproducts of the fission reaction, thereby reducing the shielding requirements. It also protects the nuclear fuel from embrittlement and corrosive attack and from hydrolysis during subsequent processing steps. CVD coatings of alumina deposited at 1000°C and beryllia deposited at 1400°C have also been studied for that purpose.P l... 

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