The Harris Supermissileweld® TIG (GTAW) Welding Rod, 1/8 in × 36 in, 10 lb Box (03SMW60) is a proprietary high-strength low-alloy (HSLA) steel filler rod designed for joining and overlaying high-strength alloy steels including HY-80, HY-100, AISI 4330, 4340, maraging steels, and similar high-yield-strength base metals used in defense, aerospace, and heavy structural applications. The Supermissileweld® formulation produces a weld deposit with exceptional toughness — maintaining ductility and notch-toughness at sub-zero temperatures while delivering 100,000–130,000 psi (689–896 MPa) tensile strength in the as-welded condition. This combination of strength and toughness is why Supermissileweld has been the specified filler in U.S. Navy, Army ordnance, and defense aerospace applications for decades.
| Specification | Value |
|---|---|
| Manufacturer | Harris Products Group |
| Part Number | 03SMW60 |
| AWS Classification | ER120S-1 (AWS A5.28 / nearest class); Harris proprietary formulation |
| Diameter | 1/8 in (3.2 mm) |
| Length | 36 in (914 mm) |
| Package Weight | 10 lb (4.5 kg) box |
| Tensile Strength (as-welded) | ~110,000–130,000 psi (758–896 MPa) typical |
| Yield Strength (as-welded) | ~100,000 psi (689 MPa) minimum typical |
| Charpy CVN Impact Toughness | >50 ft-lb (68 J) @ −100°F (−73°C) typical |
| Process | GTAW (TIG) |
| Polarity | DCEN (DC electrode negative) |
| Shielding Gas | 100% Argon (ultra-high purity 99.997% preferred for mil-spec work) |
| Preheat | 300–500°F (149–260°C) depending on base metal and restraint |
| Compatible Base Metals | HY-80, HY-100, AISI 4330, 4340, D6AC, maraging steel (18 Ni 200/250/300), HP9-4-30 |
| Military Standards | Meets MIL-E-18193 and MIL-E-24403 intent for high-strength GTAW filler |
Source: Harris Products Group Supermissileweld technical data. All mechanical property values are typical; reference Harris certified test reports for specific lot qualification data.
- Defense & Ordnance: HY-80 and HY-100 pressure hull and structural components for submarines and surface ships (per NAVSEA welding standards). Missile airframe structural joints, bomb rack fittings, and aircraft carrier structural steel where high yield strength, toughness at low temperature, and controlled hydrogen content are all mandatory simultaneously.
- Aerospace Structural: D6AC and 4340 steel landing gear components, flight-critical structural forgings, and high-strength steel attachment fittings where tensile strength requirements exceed what ER80S-B2 or ER90S-B3 can provide. Supermissileweld's fracture toughness (KIc) values are qualified for fracture-critical flight structure under MIL-HDBK-5/MMPDS criteria.
- Heavy Ground Vehicle Armor: HY-100 applique armor plate weld buildup, armor steel repair welding on combat vehicle hulls and turrets. The high toughness at −100°F meets NATO cold-temperature survivability requirements.
- Pressure Vessel & Cryogenic: Ultra-high-strength steel pressure vessels for gas storage, rocket motor cases, and specialty hydraulic accumulators operating at high pressure where weight minimization demands high-strength steel rather than stainless or conventional carbon steel.
- Motorsport & Racing Structural: High-end IMSA, CART, and IndyCar chassis structural members in 4340 or maraging steel where every gram matters and 100 ksi+ deposit strength is needed with ductility for crash energy absorption.
Why Supermissileweld vs. ER80S-B2 or ER90S-B3: ER80S-B2 (P11 filler) and ER90S-B3 (P22 filler) are elevated-temperature chrome-moly fillers optimized for creep resistance in pressure piping. Supermissileweld is optimized for ambient and sub-zero toughness at high tensile strength — an entirely different performance profile. Use ER80S-B2/B3 for high-temperature pressure piping; use Supermissileweld for high-strength structural and defense applications where toughness at low temperature matters more than elevated-temperature creep resistance.
Hydrogen control is critical: High-strength steels (above ~100 ksi yield) are sensitive to hydrogen-induced cracking (HIC). TIG is the process of choice over SMAW precisely because it produces the lowest weld deposit hydrogen content. Use ultra-high purity argon (99.997%+ UHP grade), ensure base metal and filler are clean and dry, and preheat to 300–500°F to promote hydrogen diffusion from the HAZ. Never weld without preheat on 4340 or HY-100.
Minimum heat input and pass sequence: High-strength HSLA fillers are sensitive to excessive heat input — high heat causes grain coarsening and toughness reduction in the deposit and HAZ. Use stringer beads (no weaving), limit interpass temperature to 450°F maximum, and deposit the minimum number of passes needed for the joint volume. These techniques are standard in submarine hull welding procedures and apply equally to any mil-spec high-strength TIG application.
See also Harris 3AH tool steel filler for die repair and air-hardening tool steel applications. For P22 pressure piping, see Lincoln ER90S-B3. Browse the full TIG rod collection and TIG welders.
What base metals can I weld with Harris Supermissileweld TIG rod?
Supermissileweld is designed for HY-80, HY-100, D6AC, 4330, 4340, maraging steels (18 Ni 200, 250, and 300), and HP9-4-30. These are all high-strength, high-hardenability structural alloy steels used in defense, aerospace, and specialty structural applications. It is not the correct choice for standard A36 mild steel, P11/P22 chrome-moly pressure pipe, or stainless steel.
Is Harris Supermissileweld approved for U.S. Navy submarine hull welding?
Harris Supermissileweld has been used in U.S. Navy HY-80 and HY-100 welding applications under military specifications including MIL-E-18193. Qualification for specific NAVSEA hull welding procedures requires procedure qualification testing per the applicable NAVSEA Technical Publication (e.g., NAVSEA Technical Publication T9074-AD-GIB-010/1688). Contact Harris technical support for current military qualification documentation specific to your program's specification requirements.
What preheat is required for welding 4340 steel with Supermissileweld?
AISI 4340 is a high-hardenability, high-strength steel requiring preheat of 400–500°F (204–260°C) for most welding applications. Maintain interpass temperature above preheat. Immediately after welding, transfer the part to a furnace at 400–500°F for a minimum 2-hour hydrogen bake-out or stress relief. Failure to preheat 4340 routinely causes delayed hydrogen-induced cracking, which may not appear until 24–72 hours after welding.
Can Supermissileweld TIG rod be used for hardfacing or overlay deposits?
Yes. Harris Supermissileweld is used for overlay and buildup on worn high-strength steel components where the overlay must match or exceed the base metal strength. For abrasion-resistant hardfacing (rock, mineral, or impact-abrasion applications), a dedicated hardfacing rod with higher carbide content is more appropriate. Supermissileweld is optimized for strength, toughness, and metallurgical compatibility with high-strength alloy steel base metals — not for maximum abrasion wear resistance.