Originally Posted by Biggamehit (Post 302922)

first gen ssac yea not second. made with better steel and braced.

Originally Posted by wikipedia

Intergranular corrosion
Some compositions of stainless steel are prone to intergranular corrosion when exposed to certain environments. When heated to around 700 °C, chromium carbide forms at the intergranular boundaries, depleting the grain edges of chromium, impairing their corrosion resistance. Steel in such condition is called sensitized. Steels with carbon content 0.06% undergo sensitization in about 2 minutes, while steels with carbon content under 0.02% are not sensitive to it.


A special case of intergranular corrosion is called 'weld decay' or 'knifeline attack'(KLA). Due to the elevated temperatures of welding the stainless steel can be sensitized very locally along the weld. The chromium depletion creates a galvanic couple with the well-protected alloy nearby in highly corrosive environments. As the name 'knifeline attack' implies, this is limited to a small zone, often only a few micrometres across, which causes it to proceed more rapidly. This zone is very near the weld, making it even less noticeable[5].

It is possible to reclaim sensitized steel by heating it to above 1000 °C and holding at this temperature for a given period of time dependent on the mass of the piece, followed by quenching it in water. This process dissolves the carbide particles, then keeps them in solution.

It is also possible to stabilize the steel to avoid this effect and make it welding-friendly. Addition of titanium, niobium and/or tantalum serves this purpose; titanium carbide, niobium carbide and tantalum carbide form preferentially to chromium carbide, protecting the grains from chromium depletion. Use of extra-low carbon steels is another method and modern steel production usually ensures a carbon content of <0.03% at which level intergranular corrosion is not a problem. Light-gauge steel also does not tend to display this behavior, as the cooling after welding is too fast to cause effective carbide formation.

Crevice corrosion
In the presence of reducing acids or exposure to reducing atmosphere, the passivation layer protecting steel from corrosion can break down. This wear can also depend on the mechanical construction of the parts, eg. under gaskets, in sharp corners, or in incomplete welds. Such crevices may promote corrosion, if their size allows penetration of the corroding agent but not its free movement. The mechanism of crevice corrosion is similar to pitting corrosion, though it happens at lower temperatures.

Stress corrosion cracking
Stress corrosion cracking can be a severe form of stainless steel corrosion. It forms when the material is subjected to tensile stress and some corrosive environments, especially chloride-rich environments (sea water) at higher temperatures. The stresses can be a result of service loads, or can be caused by the type of assembly or residual stresses from fabrication (eg. cold working); residual stresses can be relieved by annealing. This limits the usefulness of stainless steels of the 300 series (304, 316) for containing water with higher than few ppm content of chlorides at temperatures above 50 °C. In more aggressive conditions, higher alloyed austenitic stainless steels (6% Mo grades) or Mo containing duplex stainless steels may be selected.

Stress corrosion cracking depends on the nickel content. High nickel content austenitic (non-magnetic) steels, which are the most resistant to other forms of corrosion, tend to be the most susceptible to stress corrosion.

Chlorine catalyzes the formation of hydrogen which hardens and embrittles the metal locally, causing concentration of the stress and a microscopic crack. The chlorine moves into the crack, continuing the process.

Originally Posted by Biggamehit (Post 308692)

good stuff bro ..

yea i didnt even research that. i just went with it to get by and it has laster with the additional bracing.