When industrial welding applications call for a general-purpose welding wire that can be used for a variety of welding applications, T-1 and T-9 flux-cored wires are a frequent choice. From structural steel and shipbuilding to railcar fabrication, T-1 and T-9 wires can offer performance and versatility to meet a wide variety of applications. 

With an understanding of T-1 and T-9 wires and their characteristics, along with some tips for how to optimize their performance, companies can gain good weld quality and productivity. 

Wire classifications 
Mild steel, gas-shielded flux-cored welding wires are classified under American Welding Society (AWS) A5.20 –Specification for Carbon Steel Electrodes for Flux-Cored Arc Weldingwith the 1 or 9 usability designators (T-1 and T-9). They are the most common flux-cored wires used in industrial welding.  

Few wires are classified only as T-1, but many wires in this category are classified as both T-1 and T-9, such as the FabCO® Triple 7 wire from Hobart. This dual classification means the wire meets the requirements of both classifications without sacrificing performance or mechanical characteristics — maximizing the versatility of these wires. 

The base composition of the powder inside the tubular wire is the same for both T-1 and T-9 wires. Titanium dioxide from the mineral rutile composes most of the flux in these wires (T-1 and T-9 wires have a rutile-based slag). These powders, along with either silica, alumina or zircon act as a flux during welding to form a protective slag over the completed weld. 

The difference between a T-1 designation and T-9 designation is that a T-9 wire must meet toughness standards at a lower temperature. A T-1 wire must meet toughness requirements when tested at 0° F, while a T-9 wire is required to test at -20° F.  

Within the T-1 and T-9 product category, there are many different products available in the market today with varying strengths and weaknesses. Some are designed as “do it all” wires that provide great versatility, while others are designed to address very specific applications or needs. These specialty wires are good for niche jobs and may have enhanced mechanical properties, low diffusible hydrogen classifications or improved ability to weld through coatings or contamination. Some wires are designed to address specific needs, like lower fume or manganese exposure, or to resist moisture absorption in challenging environments and applications, which is a benefit of seamless, copper-coated wires. 

Benefits of T-1 and T-9 wires 
Because many T-1 and T-9 wires are general-purpose wires designed for many applications, they allow manufacturers to maximize versatility by using the same wire for a broad range of jobs — perhaps even for every welding need in the operation. This helps reduce the time and money spent on inventory management. 

The wires provide benefits for welding thicker, heavier plates (3/16-inch thickness and up) and applications that require high productivity. Operations that deal with material cleanliness issues — where they don’t have complete control over the condition of incoming parts — can also benefit from using T-1 and T-9 wires. 

Another good application for these wires is operations that do a lot of out-of-position welding, like when it’s not practical to move very large parts to weld them. In these applications, there are significant productivity benefits compared to gas metal arc welding (GMAW) or MIG solid and metal-cored wires.

Characteristics of T-1 and T-9 wires
There are many characteristics of these wires that make them good general-purpose wires across a wide variety of industrial welding applications. 

• Mechanical and chemical properties: In most cases, the wires provide far above the mechanical and chemical properties needed for industrial welding.  
• Hydrogen levels: H8 low-hydrogen classifications (meaning the wire has less than 8 milliliters of hydrogen per 100 grams of weldment) are commonly available with these wires. 
• Weldability: T-1 and T-9 wire classifications are known for great weldability, making them very welder-friendly. They are extremely tolerant of varying parameters, operator technique and base material conditions, such as the ability to weld over rust and scale. 
• Arc characteristics: The wires are formulated to provide a stable arc, smooth transfer and small globule size. 
• Slag system: T-1 and T-9 wires have a thin slag that is easy to remove, which helps save time and money in post-weld cleanup. 
• Spatter levels: Low spatter levels also contribute to time saved in post-weld cleanup. 
• Bead appearance: Good bead appearance and wetting action is another highlight of these wires. 

Shielding gas for T-1 and T-9 wires
The use of an external shielding gas is required for these gas-shielded flux-cored wires as opposed to self-shielded flux-cored wires. 

Many wires in the T-1/T-9 classification can be used with either 100% carbon dioxide or an argon/CO₂ mixed shielding gas, depending on the specific wire and desired welding characteristics. The AWS classification will denote a C or an M (or both) to designate the shielding gases that can be used with the wires. 

Operators will see differences in the performance characteristics and mechanical properties of the weld depending on which gas they use, and there are pros and cons to both gas options. 

Using a 100% carbon dioxide gas typically provides greater penetration, but it can also result in more spatter, a more erratic arc and welds with a lower tensile strength and higher ductility. In comparison, using an argon/CO₂ gas blend offers less spatter, a very stable arc, and a weld with higher tensile strength and lower ductility, but it also delivers less penetration. Although the typical mechanical properties of the wires will differ depending on the shielding gas that is used, if a wire is classified to be used with both C (100% CO₂) and M (argon/CO₂ mix), the product will meet or exceed all requirements of its classification.

Recommended techniques
While the wires are very tolerant of variances in operator technique or welding parameters, there are a few best practices that can help optimize results when welding with T-1 and T-9 wire classifications. 

One of the biggest tips is to use a drag technique with a slag-producing wire, rather than using a push technique (as with a GMAW or MIG wire). 

In addition, a slightly longer stickout should be used than what is used with solid wire MIG welding. Generally, arc characteristics deteriorate with a longer stickout, and the arc will start to become unstable. But flux-cored wires can tolerate a longer stickout and still maintain their arc characteristics. 

Maximize versatility with T-1 and T-9 wires
Wires under the T-1 and T-9 classification provide excellent weldability, low spatter and nice bead appearance. In addition to these characteristics, the wires have wide operating windows and are more tolerant to the operator’s technique, which can help manufacturers improve the productivity and quality of less-experienced welders. 

T-1 and T-9 wires are often a good option in general manufacturing applications that don’t require extreme toughness or other mechanical properties. It’s important to understand the characteristics of a wire and when it performs best to choose the right option for a specific welding application.