letter 14356 Differences between 316 and 316L   ++ What are the differences between 316 and 316L, as it seems that there are some differences. Would 316L be any much difference to corrosion resistance than 316? Richard Ashley - Singapore ++ Richard, 316L has lower carbon allowed. It will be less susceptible to sensitization, a condition caused when carbon combines with chromium around the grain boundaries, thereby depleting the grain boundary areas of chromium. That would make the grain boundary areas less corrosion resistant. Sensitization occurs with heating into the 800 F to 1300 F region, so it's a welding or annealing problem. The 316L will also be softer than straight 316, again due to the lower carbon. Good luck! Lee Gearhart metallurgist East Aurora, NY ++ The difference between 316 and 316L is the amount of carbon that is in the material. 316 has .08 Max carbon content while 316L has a .03 Max carbon content. I am not aware that there is a significant difference in the corrosion resistance of one over the other. The primary reason for using an L grade of stainless steel is that this will reduce the tendency of the material to crack after welding. If you use a stainless steel with a high carbon content the welds may crack spontaneously as they cool down from the welding. This type of cracking is known as "hot brittleness". In short, if the item you are fabricating will be welded then use an L grade material. If it is not then it does not matter. I hope this helps you. John Holroyd - Elkhorn, Wisconsin ++ 316 and 316L differ only by the amount on carbon in them. As I understand it, 316 L has lower carbon such that when welded the chromium carbide that forms does not deplete the chromium to the point where the corrosion of the stainless is deleteriously impacted. This effect, known as chromium depletion, shows itself in most plating shops where 316 welded tanks are used. The welded corners typically rust whereas the bulk of the exposed stainless is untouched. 316 has a carbon content of 0.08% Max whereas 316L is 0.03% Max. Milt Stevenson, Jr. Anoplate Corp Syracuse, NY, USA ++ The main difference is the lower carbon content, 316 being 0.030, 316L being as low as 0.016. Other elements are also somewhat lower,such as sulfur, phosphorus and copper. The 316L is more ductile when annealed, and is markedly more corrosion resistant, especially after welding. 316L is much more weld friendly than 316, as it is less susceptible to intergranular corrosion, after welding or air service up to 1600 F (intermittent) 1700 F (continuous), due to carbide precipitation. In 316 carbide precipitation will occur between 900 F-1070 F after 9 hours, whereas 316L will precipitate carbides between 900 F-1010 F after 181 hours, 316L showing much more resistance to sensitization. Jeff Swayze - Kelowna, B.C., Canada +++++++ The Temperatures at which the precipitation of Chromium carbides is present is between 1004-1553 F. Source: ASM Materials Engineering Dictionary [link is to product info at Amazon] Purusha Bonnin - Barberton, OH, US January 6, 2009 Beside sending the materials to labs, is there a cheaper or easier way to test the difference in carbon content in order to differentiate 316 vs 316L. eg. by hardness test? if this is possible, what is the difference in term of the hardness? Pls comment Pat Png industrial supplies - Singapore July 15, 2009 How we differensiate between 316L gasket & 316 gasket Mahadev Gosavi hobbyist - India

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