July 28th | Lunch and Learn | Featuring Talks and Demos on Hydrogen in Shielding Gas, High Deposition Welding, and Welding Contact Tip Life Extension

When: Thursday, July 28th at 11:30 am – 2:30 pmWhere: ARC Specialties, 1730 Stebbins Drive | Houston, Texas 77043Cost: FreeRSVP: The first 25 companies to RSVP to lindsay@arcspecialties.com will receive a packet of the new long-life contact tips from ARC Specialties on the day of the event.

Material Covered at the July 28th Lunch and Learn:Due to falling oil prices, the industry has endeavored to do more with less. ARC Specialties has recently completed work in three areas of interest in Hot Wire GTA Welding: 1.) the use of hydrogen blends in shielding gas, 2.) high deposition welding and 3.) contact tip life extension.1. Hydrogen Shielding GasThe thesis is that the use of 98%Ar 2% H2 shielding for GTA Hot wire ERNiCrMo-3 “625” welding reduces defects and improves productivity. Most 625 defects are oxide inclusions. Hydrogen has a strong affinity for oxygen, so it acts like a flux to reduce oxides from part, wire and shielding gas contamination. There is industry resistance to use hydrogen gas for shielding as 625 overlay is specially intended to mitigate hydrogen induced cracking.However, ERNiCrMo-3 is not a low hydrogen filler material at 8.5ppm hydrogen. Hydrogen in the wire accounts for 90% of the diffusible hydrogen in the weld, when welding with 98Ar 2%H2. Pre- and post-heat reduce diffusible hydrogen by 30%. In the worst case scenarios, with no pre-heat, immediate quench and holding in liquid nitrogen, there is only .9ml/100g in the weld metal. This is less than half of the most stringent published low hydrogen specification. Full weld procedure qualification tests were conducted on both argon & argon/hydrogen weld tests to demonstrate that mechanical properties are not affected. Finally, using a microscopic examination technique, the team has quantified weld quality to show that weld quality improves with hydrogen blends.

2. High Deposition Welding

Many manufacturers GTA Hot Wire Clad at 80 IPM (2 m/min) with .045” (1.2 mm) wire. This deposition rate is 2 lbs /hour (.9 kg/hour). ARC is working to improve on this in three ways. The first is to simply increase deposition while welding with argon in the 2 G position. ARC Specialties has pushed wire feed speeds up to 300 IPM (10 m/min) resulting in 8 lbs/hour (3.6 kg/hr) in production with a single wire. The team has also developed single layer procedures which meet the <5% Fe standard and pass <250 Vickers HAZ hardness after post weld heat treatment. Finally, ARC Specialties has achieved 10 lbs./hr (4.5 kg/hr) with a single layer welding at a 45 degree angle. The following 4 procedures were recently qualified, passing base tensile & impact, weld side bends, weld chemistry, and hardness HRC & Vickers, with both 1175 degrees F for both 4 and 12 hour PWHT.

Deposition rate in pounds/hr.	Number of total layers	Iron content %	Welding Position	PWHT 1175F (635C)
6	1	2.6	2 G	4 and 12 hours
8	1	3.1	2G	4 and 12 Hours
6	2	3.6	2G	4 and 12 Hours
10	2	4.1	45 Deg	and 12 Hours

3. Contact Tip Life Extension

High deposition welding necessitates high wire speeds, which degrade tip life. Standard copper contact tips tested at 8 lbs/hour wear at a rate of .0036”/lb. Several other tips materials were tested with wear ranging from .00220” to .00025”/lb (best). Testing also determined that typically, .01” of wear will necessitate an adjustment in contact tip position to maintain correct wire to puddle alignment. New tips from ARC Specialties are able to operate for 5 hours without adjustment when welding at 8 lbs/hr, a 1600% improvement.

Tip Type	Wear (inches/lb)	Time before .01” wear position adjustment at 8 lbs/hr
Standard Copper	.0036	34 minutes
ARC Alloy Tip	.00025	5 hours (10 X improvement)