Welding 4140 versus 4130

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Has anyone on here welded any 4140?  I'm looking at 4130 and 4140 on McMaster.com, and they don't have the size/shape I need in 4130.  They describe 4140 as being "fair" to weld with 4130 being in the most weldable category of "good".  They go on to say the 4140 is "Hardened and Tempered and Quneched" with a hardness of Rockwell C28 - C32, which isn't terribly hard.I need very straight strips of 1.5" x .25" about 32" long for this project.  I actually ordered a couple of 6" x 36" plates of the 4130 from McMaster planning on plasma cutting the strips, but they were sheared to size and ended up with a pretty good bow to them.So, what do ya'll think?  How would the 4140 react to tig welding?  I have a very short deadline on this project, and don't think I can get correct sized 4130 in quick enough where I can get the 4140 overnight.Thank you,Jason
Reply:Originally Posted by TubularFabHas anyone on here welded any 4140?  I'm looking at 4130 and 4140 on McMaster.com, and they don't have the size/shape I need in 4130.  They describe 4140 as being "fair" to weld with 4130 being in the most weldable category of "good".  They go on to say the 4140 is "Hardened and Tempered and Quneched" with a hardness of Rockwell C28 - C32, which isn't terribly hard.I need very straight strips of 1.5" x .25" about 32" long for this project.  I actually ordered a couple of 6" x 36" plates of the 4130 from McMaster planning on plasma cutting the strips, but they were sheared to size and ended up with a pretty good bow to them.So, what do ya'll think?  How would the 4140 react to tig welding?  I have a very short deadline on this project, and don't think I can get correct sized 4130 in quick enough where I can get the 4140 overnight.Thank you,Jason
Reply:What Rojo said. If it's not a critical weld you can get by with pre-heat and a SMALL weld...otherwise...post weld heat-treat (oven/furnace)Anything worth doing is worth doing RIGHT
Reply:This is on an odd project - a skeleton sled like used in the winter Olympics.  The goal is to have the main rails very stiff, and they are about 3 feet long and only 1/4" thick.  The joints have a lot of overlap and therefore a lot of weld area for the load they see.I did at least find some 4140 annealed and cold rolled to use rather than the partially hardened I mentioned above.  I did 2 quick sample parts welding on one side of a tee joint only.  One weld was done using mild steel (ER70s...) as the filler, and the other was with silicone bronze filler and less heat.  After they cooled I bent them the easy way to break the weld.  The ER70 joint cracked right down the middle of the weld fillet in a fairly brittle manner with little bending first.  The silly bronze seemed much more ductile, and bent about 90 degrees before finally breaking.So, would the ER80... filler give me a little more ductility?  Or should I just go with the silicone bronze?Thank you,Jason
Reply:Go Titanium and call it a dayDisclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:70 will give you more ductility than the 80 will.  If the everdur will do the trick, have at it.
Reply:if i understood this right (probably missed something since i've been in the pub all night, hic.),...using 4140 (or 4130) won't make the rails any stiffer than if 1020 were used since the modulus of elasticity (E) is virtually the same for all three. Ti has a considerably lower E value FWIW
Reply:Originally Posted by TubularFabThis is on an odd project - a skeleton sled like used in the winter Olympics.  The goal is to have the main rails very stiff, and they are about 3 feet long and only 1/4" thick.  The joints have a lot of overlap and therefore a lot of weld area for the load they see.I did at least find some 4140 annealed and cold rolled to use rather than the partially hardened I mentioned above.  I did 2 quick sample parts welding on one side of a tee joint only.  One weld was done using mild steel (ER70s...) as the filler, and the other was with silicone bronze filler and less heat.  After they cooled I bent them the easy way to break the weld.  The ER70 joint cracked right down the middle of the weld fillet in a fairly brittle manner with little bending first.  The silly bronze seemed much more ductile, and bent about 90 degrees before finally breaking.So, would the ER80... filler give me a little more ductility?  Or should I just go with the silicone bronze?Thank you,Jason
Reply:TubularFab,If you want it stiff, all steels are the SAME with regards to stiffness.  It doesn't matter if the item is made of 1018, 4130 annealed, or D2 at Rc=62, the -stiffness- of the part would be the same.  The strength and the load at which the part yields and takes a permanent bend or deformation would vary a lot.If you need an item to be stiff, you need two main things.  You need to use a material with a high modulus of elasticity (the E value mentioned above).  And the E for steel is 29 x10^6 psi, for pretty much -any- alloy or heat treatment.  The second thing is to make the part shape to be stiff.  One way to make a shape stiff is to use a hollow section instead of a solid section.  The solid section may be stronger for the same size compared to a hollow section, but the hollow section will usually be stiffer for the same weight compared to a solid section.btw, there isn't much difference in welding or other material properties from 4130 to 4140 steel.  All the alloy change did was bump the carbon content from 0.30% to 0.40%.  Changing from 4130 to 4340 is a bigger change, because you are not only changing the carbon content slightly but also changing from a cro-moly alloy to a cro-moly-nickel alloy.  4130 can usually handle a water quench (at least in smaller sections), while 4340 usually will call for an oil quench.  4130, water quenched from 1570F and 900F temper in 1/2 inch round bar, has a Rc=36 and a yield strength of 161 ksi.  4340, oil quenched from 1470F and 1000F temper in 1/2 inch round bar, has an Rc=40 and a yield strength of 169 ksi.