A500 Gr.B/CのSMAW (non-low-hydrogen)用予熱 — 3/4" to 1-1/2"

SMAW (Non-Low-Hydrogen)

Non-low-hydrogen SMAW (E6010/E6011) uses cellulosic electrodes with higher hydrogen potential, assigned to Category A in Table 5.11.

For common structural shapes and plate, non-low-hydrogen SMAW with E6010 or E6011 excels at root passes on open-root groove welds where burn-through control matters. Vertical-up technique with a slight weave keeps the puddle manageable. Rod consumption runs about 10-12 electrodes per pound of weld metal deposited. Electrode stubs should be no shorter than 2 inches to maintain adequate arc length control.

A500 Gr.B/C

ASTM A500 Grade B (46 ksi yield for round, 42 ksi for rectangular) and Grade C (50 ksi round, 46 ksi rectangular) cover cold-formed welded and seamless structural tubing — round, square, and rectangular HSS sections. These are the standard tubular members in building frames, trusses, and signage structures, produced in wall thicknesses from 16 gauge (0.065") up to 5/8" for rectangular and 1/2" for round. Table 5.11 assigns both Category A and B preheat requirements. The cold-forming process work-hardens the corners, producing corner radii with higher hardness (up to 20% increase) and reduced ductility compared to the flat faces. This affects welding behavior at corner locations, particularly on heavily loaded connection details where weld starts or stops near corner radii can create initiation points for fatigue cracks.

A500 Gr.B/CとSMAWでこの予熱が必要な理由

Cold-formed structural tubing for HSS sections in frames and trusses. At this thickness, SMAW with non-low-hydrogen electrodes places the joint in Category A of Table 5.11. The minimum preheat of 150°F compensates for the higher diffusible hydrogen from cellulosic electrode coatings. The thicker the material, the longer hydrogen takes to escape the heat-affected zone, which is why preheat rises with thickness even for this common grade.

A500 Gr.B/Cの代表的な適用例

Standard for HSS columns in office buildings, hollow section trusses in warehouse roofs, exposed architectural tube steel, sign structures, solar panel racking frames, greenhouse frames, and guard rail posts. A500 tube-to-tube moment connections require through-plate or diaphragm detailing to transfer forces across the closed section. Slotted gusset connections into HSS bracing members are a signature fabrication detail requiring careful fit-up and beveling of the gusset plate. Common sizes include HSS 6x6x3/8 and HSS 8x8x1/2 for columns, HSS 4x4x1/4 for bracing, and HSS 10x6x3/8 for rectangular beam applications. The cold-formed corner radius creates a heat-affected zone consideration that differs from hot-rolled shapes when planning multi-pass weld sequences. Round HSS pipe columns are also common, typically HSS 6.625x0.280 through HSS 12.750x0.500 for mezzanine posts and canopy supports. Fillet welds connecting HSS to cap plates and base plates are the most frequent weld joint detail.

3/4" to 1-1/2"で予熱が重要な理由

Preheat climbs at this range as thicker material slows heat dissipation, trapping hydrogen at crack-susceptible grain boundaries.

SMAW (non-low-hydrogen)と3/4" to 1-1/2"における他の鋼材

A500 Gr.B/CとSMAW (non-low-hydrogen)

別の組み合わせを試す

インタラクティブ予熱計算機を使用して、D1.1:2025 表5.11のあらゆる鋼材・プロセス・板厚の組み合わせを検索できます。

A500 Gr.B/C溶接ガイド