View Full Version : Differnce between 304 and 316 ss

rajun asian
07-06-2007, 03:19 PM
Hi everyone. I work in a factory that makes cabinets and fume hoods for labs and such. I know that 316 is more corrosion resistant than 304. But what gives it that property?

Also, if i have a piece of 304 and 316 that are identical in size and thickness, will one piece be heavier than the other. Is one more dense than the other? These are some questions being tossed around the place and since I'm not a metallurgist, I figured someone here may be able to give me some correct info to pass along.


07-06-2007, 04:11 PM
Welding filler metal guide - stainless steels


ER308: Suitable for welding austenitic stainless of the 18/8 type. Excellent intermediate layer for deposition of hard-surfacing material.
ER308H: Basically the same qualities as 308, but with a higher carbon content. Often used in many chemical applications.
ER308L: Used in similar 308 applications, but with improved resistance to intergranular corrosion due to lower carbon content. Welds AISI types 304, 308, 321, and 347.
ER308L Hi Sil: High silicon version of 308L. Silicon improves arc stability and leaves an exceptionally smooth bead appearance. Weld requires little or no finishing work. May be used with CO2 gas in some GMAW applications.
ER308SI: Suitable for joining 304 and 347 type stainless steels for service temperature up to 660°F . Same as ER308 except for the higher silicon content, which improves the usability in GMAW.
ER309: Higher content of Chrome and Nickel, suitable for welding heat-resistant base metal of similar composition. Commonly used to join carbon steel to austenitic steel. Intended working temperatures up to 570ºF.
ER309L: Same qualities as 309 but with lower carbon content necessary in many chemical applications.
ER309LMO: Same as ER309MO except for a lower carbon content (max 0.03%). ER309LMO is used in the same type of applications as the ER309MO. In several layer welds, the low carbon ER309LMO is usually needed for the first layer in order to achieve low carbon contents in successive layers with filler metal such as ER316L or ER317L.
ER309L: Hi Sil is a high silicon version of 309L. Higher silicon gives arc stability and exceptionally smooth bead appearance.
ER310: Used to weld austenitic heat-resistant steels, also certain stainless chrome steels. The weld is practically free of ferrite which can produce hot cracks; however, measures to reduce shrinkage stresses are recommended in critical cases.
ER310H: Same as ER310 with slightly more carbon. Primarily used to weld or repair high alloy heat and corrosion resistant castings of the same general composition, designated as type HK by the Alloy Castings Institute. High strength at temperatures over 1700ºF.
ER312: Useful for welding dissimilar metals, of which one component is high in nickel. Gives a two-phase weld deposit with substantial percentages of ferrite in an austenite matrix. Even with considerable dilution by austenite-forming elements such as nickel, the microstructure remains two-phase and thus highly resistant to weld metal cracks and fissures.
ER316: Recommended for welding AISI 316 stainless steel applications where high creep strength at elevated temperatures and resistance to pitting by corrosive liquids is needed.
ER316H: Same qualities as 316 but with a higher carbon content deemed necessary in many chemical applications.
ER316L: Suitable for welding acid-resistant steels such as 316 and 316L. Welds produced have good resistance to corrosion in most inorganic and organic acids, and to pitting in chloride-bearing solutions.
ER316LSI: Same characteristics as 316L. The low carbon in the weld metal gives excellent assurance against intergranular corrosion. Hi Sil allows better arc stability along with minimal post-weld grinding.
ER317: Recommended for welding austenitic acid-resistant steels. High molybdenum content provides a weld with improved resistance to general corrosion in most inorganic and organic acids and to pitting in chloride bearing solutions. Low carbon protects against intergranular corrosion.
ER317L: Same as ER317, but with lower carbon content necessary in many chemical applications.
ER320: Used in welding base metals of similar composition (20Cb-3) for applications where corrosion resistance to sulfuric, sulfurous acids and other chemicals is required.
ER320LR: Similar to ER320, except that the carbon, silicon, phosphorus, and sulfur levels are kept at lower levels as well as the columbium and manganese being recommended or specified at a narrower range. Residuals are limited to reduce the possibility of micro fissuring. This alloy is often used for welding type 320 stainless steels.
ER330: Used in welding 330 stainless, cast and wrought material of similar analysis. Excellent strength; excellent heat and scale resistance up to 800ºF.
ER347: Recommended for welding AISI 347 and 321. The weld metal has good resistance to general corrosion. Columbium stabilization provides assurance against intergranular corrosion. ER347 is suitable for applications where welds are subjected to high temperatures (750+ºF).
ER347SI: Suitable for joining stainless steels of the 18Cr / 8Ni / Cb and 18Cr / 8Ni / Ti types. This grade is recommended if the weld metal is to be subjected to high temperatures above 750ºF.
ER409: The nominal composition of this weld metal is 12% Chromium with Ti added as a stabilizer. This material often is used to weld bare metal of similar composition.
ER409CB: Same as ER409 except that columbium (niobium) is used instead of titanium to achieve similar results. Oxidation losses across the arc generally are lower. Applications are the same as those of ER409 filler metals.
ER410: Used for welding types 403, 405, 410, 414 and 416. Also an overlay on carbon steels for corrosion, erosion and abrasion resistance.
ER410NiMo: Used primarily to weld cast and wrought material of similar chemical composition. Recommend using preheat and interpass temperature of not less than 300ºF. Post-weld heat treatment should not exceed 1150ºF, as higher temperatures may result in hardening.
ER420: Similar to type 410 except for a higher carbon content. Primary use is for overlaying applications where a higher hardness provides excellent abrasion resistance along with corrosion and erosion resistance.
ER430: Used for welding type 430 stainless steel.
ER502: Used for welding 502 base metal, frequently tube or pipe. Preheating and post-weld treatment are required.
ER505: Used for welding tube or piping of similar composition. Preheating and post-weld heat treatment are required.
ER630: Designed primarily for welding ASTM A564 type 630 and some other precipitation-hardening stainless steels. The composition is modified to prevent the formation of ferrite networks in the martensitic microstructure which has a great effect on mechanical properties. The weld metal may be used either as welded, welded and precipitation hardened, or welding and solution treated.
ER2209: Intended to weld duplex stainless steels. The weld metal exhibits high tensile strength and improved resistance to stress, corrosion, cracking and pitting. The wire exhibits a lower ferrite compared to that of base metal for improved weldability.

07-06-2007, 04:12 PM
I had a definition of base materials as well, but cant find them. That gives you an idea with the filler descriptions.

07-06-2007, 04:14 PM
For all practical purposes, the density of 304 and 316 are the same.

The piece that is heavier will weigh more. :laugh:

The chemical differences between the two alloys are that 316 -may- have a smidge more nickel in it and -may- have a smidge less chromium in it, but the main difference is that 316 has some molybdenum in it. That means the 316 is a little bit more resistant to certain types of corrosion, but not necessarily to any and all types of corrosion or corrosive items.

You could use google or other search engine to find answers like this. Or ask the metallurgists or pick up or borrow a metallurgy text or reference.

rajun asian
07-06-2007, 04:25 PM
Thanks for the quick replies guys. That's why I love this site!:cool2: