Once you&#;ve invested in a top of the line TIG welding machine for aluminum welds or detailed projects, get the most out of your welds by picking the right TIG welding tungsten. Whether you&#;re using AC or DC processes for TIG welding, here are some tips to keep in mind when it&#;s time to stock up on TIG rods, including a new rod you may not know about. At the end of the post we&#;ll also link to a Baker&#;s Gas and Welding customer favorite.
For more information, please visit Lanthanated Moly.
Each TIG welding electrode has a specific color classification that makes them easy to identify. Based on the composition of the electrode, welders will find specific applications and benefits that may work best for each electrode. Here is a brief roundup:
Green TIG Welding electrodes are pure Tungsten and are used for AC welding, often for aluminum and magnesium. They tend to be commonly used because they are inexpensive. However, they also burn up much faster than the other alloy electrodes, so prepare to stock up if you go this route.
Why use green, pure tungsten electrodes? They work well on AC sine wave welding and form a solid balled tip that results in a stable arc. Besides the high consumption rate, it doesn&#;t start as well as thoriated or ceriated electrodes, which remain the favorites among many welders.
Red Thoriated TIG Welding Electrodes are among the most commonly used electrodes because the 2% thorium mixed with the tungsten is durable and versatile. Welders can grind the tip of these electrodes to a sharp point and enjoy and stable arc that last a long time. The final weld puddle is cleaner since the electrode leaves fewer deposits, and thorium allows for easier arc starts and higher current-carrying capacity.
Switch between AC or DC welding with Thoriated electrodes. Welders can work on projects that include thin aluminum, titanium, carbon steel, stainless steel, and nickel. Since thorium is radioactive, welders remain cautious about using these electrodes.
Orange Ceriated TIG Welding Electrodes contain about 2% percent ceriated and are ideal for DC welding and lower current processes. Since it can weld carbon steel, stainless steel, nickel alloys, and titanium, some welders have found that it works well as a replacement for thoriated electrodes.
Ceriated is not recommended for welding at higher amps since the heat can change the composition of the electrode. Welders prefer to work with Ceriated electrodes at lower temperatures for small, precise parts, pipe fabricating, and welding thin metal.
Gold Lanthanated Electrodes for TIG Welding work in both AC and DC (electrode negative) settings since they can be sharpened or balled respectively depending on the project. It can weld steel from a square wave power source and it offers reliable arc starts and arc stability.
Due to its durability and versatility, some welders use Lanthanated in place of thoriated since there are no radioactive elements in the metal.
Brown Zirconiated TIG Welding Electrodes have a minimal amount of Zirconium and are best used only for AC welding jobs. Since the zirconium is a strong metal that resists cracking, it produces a stable arc and resists contamination. It can also carry an amperage current that is comparable to thoriated electrodes.
Gray Rare Earth Electrodes typically note which rare-earth oxides are present in the rod. These electrodes can be used for AC and DC welding jobs, but welders should take care to read the details of each metal listed on the package. At their best, rare earth electrodes can be counted on for a stable arc, longer life, and a current that rivals other electrodes even though they are usually smaller.
Can&#;t decide which electrode to purchase? Try out the new Weldporn Five Flavors Assorted Tungsten. These electrodes have been proven to provide stability and consistency in every weld. There are two of each electrode included in the set.
The options for the 3/32&#; electrodes include:
2% Thoriated
2% Ceriated
2% Lanthanated
Multimix
Pure Tungsten
The Purple Electrode Option
Purple E3 Tungsten If you&#;re looking for a safe alternative to thoriated electrodes and a longer lasting version of pure Tungsten, then you may want to consider the E3 Tungsten electrode that blends three oxides together. It has better ignition rates, it runs cooler, and there is no radiation. Compared to thoriated, it may even sustain a faster ignition and a more stable arc over time.
The E3 Tungsten is designed to give better arc starts and a longer lifespan for the electrode compared to pure Tungsten.
If you are planning to TIG weld with Aluminum check out this blog post.
Check out our YouTube video going over some common questions on Tungsten.
Chrome-moly steel offers a good blend of strength, weight and ductility for many motorsports and aerospace applications. The following article discusses some of the recommended procedures and equipment for successfully TIG welding chrome-moly steel.
Published: March 18,
Archived
For more Molybdenum Lanthanuminformation, please contact us. We will provide professional answers.
Todd Bevis poses with one of the chrome-moly roll cages he builtTodd Bevis poses with one of the chrome-moly roll cages he built
By: Todd Bevis, Chassis Engineer, Cagnazzi Racing and Andy Weyenberg, Motorsports Coordinator, Miller Electric Mfg. Co.
Just as a NHRA (National Hot Rod Association) drag racing team depends on blend of team talent to win races, the material selected for a particular application requires a blend of properties to withstand the stresses involved. For a drag racing chassis, and for many other motorsports and aerospace applications, that material is chromium-molybdenum, or chrome-moly, which is selected for its blend of ductility, strength, weight and fabrication advantages.
The grade of chrome-moly is a high-strength low-alloy (HSLA) steel that contains molybdenum (0.15 - 0.25 percent by weight) and chromium (0.8 - 1.1 percent by weight) as strengthening agents. However, it has relatively low carbon content (nominally 0.30 percent), so it welds, machines and bends almost as easily as DOM mild steel tubing (which has an 0.18 percent carbon content).
Fig. 1&#;A comparison of chrome-moly to DOM tubing (cold drawn, normalized state)
Material Tensile Strength Yield StrengthChrome-moly is not lighter than steel, a common misconception. Both weigh about 491 lbs. per cubic foot. However, as Fig. 1 shows, chrome-moly offers a better strength-to-weight ratio and better elongation (a measure of ductility), which enables designers to use thinner wall and/or smaller diameter tubing to reduce overall weight.
Because many motorsports, aerospace and sporting goods applications involve welding normalized chrome-moly tubing with a wall thicknesses of < .125-in., this article will focus on best practices for these applications.
Fig. 2 summarizes the welding procedures, consumables and variables required for most tubing applications. The images and text that follow expand on this information to provide further clarification and guidance.
Fig. 2&#;Summary advice for welding chrome-moly
Material chrome-moly tubing (normalized). Thickness < 0.125 in. Most chassis tubing has a wall thickness ranging from 0.035 &#; 0.083 in. and diameters from 1/4 - 1-5/8 in. Amperage 1 amp per .001 in. of wall thickness. Polarity DC Electrode Negative. HF for arc starts only. Pulsing Optional. Filler Material
When welding thin-wall tubing, whether chrome-moly or other metals, the welders at Cagnazzi Racing joke that their tolerances range from perfect to almost not perfect. That is, if the parts don&#;t fit perfectly, they start over because thin-wall tubing does not have sufficient mass to absorb excess heat.
The usual &#;trick&#; to filling gaps with GTAW is to use a larger diameter filler rod. However, larger rods require more heat, and excess heat promotes burn-through, warping and embrittlement. Using a larger rod might be an acceptable solution in a non-critical application, but it&#;s a poor practice when welding chrome-moly. Fig. 3 shows an example of perfect fit-up, with the proper diameter filler rod shown for perspective.
Figure 3Cagnazzi uses hundreds of jigs and fixtures bolted to a surface that is flat to within a few thousandths of an inch for fabricating even the smallest items to help ensure tight fit-up and consistent tube placement, which provides repeatability (see Fig. 4).
By producing a new chassis nearly identical to the previous, the crew chief can hone his craft of gear ratio and clutch management without worrying about a new chassis introducing unknown variables. Many fabricators believe that they cannot afford to build fixtures for all of their components or for larger weldments. However, if repeatability and accuracy are important, good fixturing is mandatory.
Most of Cagnazzi&#;s jigs have a go/no-go type fit, which enables &#;sneaking up&#; on a perfect fit by making small incremental adjustments.
Figure 5 Figure 6After cutting to approximate length with a band saw, Cagnazzi uses a tube notcher (Fig. 5) for rough coping. The fabricator will then check the length and use a drum sander to sneak up on a perfect fit by slowly sanding away excess metal from the mouth of the tube (Fig. 6). Before welding, the fabricator will deburr the edge (Fig. 7), clean back 1 in. from edge using Scotch-Brite or 120 grit sandpaper and remove oils or other contaminants with a solvent (Fig. 8). Be sure to wear nitrile gloves, as the natural oils from your fingers can ruin a weld just as thoroughly as grease or cutting fluid. Don&#;t forget to use the sandpaper and solvent on the filler rod, too.
In many motorsports and aerospace applications, engineers want some degree of ductility in the weld to help absorb impacts and prevent cracking. For this reason, most NHRA fabricators intentionally dilute the strength of the parent material by selecting ER70S-2 for filler for roll cages, chassis and other applications requiring more flexibility. While actual tensile strength of the weld will vary and depend on other factors, diluted with ER70S-2 filler likely produces a weld with a tensile strength in the 80,000 to 82,000 psi range.
For areas requiring higher strength, such as spindles and upper and lower control arms, fabricators select ER80S-D2 filler, which produces welds with a high tensile strength (as a side note, consider that S-2 fillers clean impurities better than D-2 fillers). In any event, do not use filler, as the weld will not have sufficient ductility unless it undergoes stress relief.
As for filler rod diameter, use a rod diameter that matches the thickness of the base metal. Trying to weld 0.035-in. tubing with a 1/16th inch filler (0.063-in.) is a bad idea because the tubing wall will melt before the filler rod is up to temperature. Cagnazzi predominantly uses 0.030-, 0.045- and 0.063-in. (1/16th) filler rods (Fig. 9), with .045 and .063 being the most common. For thicker, larger diameter tubing they use 3/32- and 1/8-in. rods.
Figure 9
Successfully welding requires preserving its mechanical properties by heating and cooling the weld in a controlled manner. Excess heat causes carbide precipitation, and cooling too quickly causes embrittlement. Fortunately, the GTAW process provides sufficient heat control. Welds made on tubing 1/8-inch or thinner do not require pre-heating or post-weld stress relief, yet they will have sufficient penetration as long operators follow the general rule of the thumb by using 1 amp per 0.001 in. of metal thickness. In Fig. 10, the operator prepares to weld thin wall tubing.
Figure 10Note that if the tubing is below 60 degrees F, use a small propone torch to heat the base metal to up to 300 degrees F. Otherwise, the metal could cool too quickly and become brittle. Welding cold metal may also promote hydrogen cracking, so that&#;s another reason to preheat if it&#;s cold.
While welding too slowly increases overall heat input, operators should not necessarily focus on welding travel speed. Rather, they should focus on controlling their body (Fig. 11), controlling puddle size by making the puddle only as wide as necessary and holding a tight arc length of 1/8-in. or less (Fig. 12).
Figure 11 Figure 12Note that a longer arc length, or tungsten tip-to-work distance, increases overall heat input because a GTAW power source automatically increases voltage when arc length increases. If the joint configuration limits access because of cup size, do not try to weld with a longer arc. Rather, use a smaller cup or a gas lens and extend the tungsten.
To better control heat input, and to enable repositioning the body to better control torch movement, do not weld the circumference of a tube in one pass. Rather, weld it in four quarters. Weld only two of the quarters (on opposite side of the tube) then move to another joint. When the first joint cools, come back and complete the remaining sections.
The authors of this article weld tubing in critical applications, and they have a combined 50 years of welding experience. As such, they take every step of the fabrication process seriously. &#;Close enough&#; is simply not good enough for NHRA or aerospace work, nor should it be for even a child&#;s go-kart or bicycle. While professionals weld most chrome-moly tubing, the aspiring chassis fabricator or experimental aircraft enthusiast can weld it at home. In any circumstance, follow proper procedures and any applicable codes and standards.
Contact us to discuss your requirements of Lanthanum Moly. Our experienced sales team can help you identify the options that best suit your needs.