A913 Gr.50/60/65 Preheat for FCAW (H8) — all thicknesses

FCAW (Flux Cored Arc Welding)

FCAW uses tubular flux-cored wire, available gas-shielded (E71T-1) or self-shielded (E71T-8) for field work. Category B in Table 5.11.

High-strength FCAW wires such as E81T1-K2 and E91T1-K2 provide tensile matching for Category C steels. The flux system in these wires is formulated for low diffusible hydrogen, often meeting H8 supplementary limits when tested per AWS A4.3. Wire storage requires climate-controlled conditions similar to SMAW electrodes to prevent moisture absorption.

A913 Gr.50/60/65

ASTM A913 Grades 50 (50 ksi yield), 60 (60 ksi yield), and 65 (65 ksi yield) are quenched-and-self-tempered (QST) structural shapes produced by thermo-mechanical controlled processing (TMCP) — an in-line water quench immediately after the final rolling pass, followed by self-tempering from the core heat. This produces a fine-grained bainitic/ferritic microstructure throughout the full cross-section with carbon content typically 0.10-0.16% and CE-IIW of 0.35-0.42. Standard low-hydrogen processes use Category B; H8-certified consumables qualify for the reduced Category D (32°F all thicknesses), reflecting the inherent hydrogen cracking resistance of the TMCP microstructure. Available exclusively as W-shapes (primarily W14 heavy column sections), A913 is not produced as plate or other forms. The QST process eliminates the need for separate mill heat treatment, providing consistent through-thickness properties.

Why This Preheat for A913 Gr.50/60/65 with FCAW

TMCP structural shapes for seismic frames with H8-eligible reduced preheat. Using H8-certified consumables with FCAW qualifies this combination for Category D in Table 5.11, which assigns 32°F minimum preheat across all thicknesses. The H8 designation limits diffusible hydrogen to 8 mL per 100g of deposited weld metal. Combined with the inherent crack resistance of this steel, the low hydrogen input eliminates the need for thickness-dependent preheat increases.

Typical Applications for A913 Gr.50/60/65

Specified for seismic moment frame columns, high-rise building corner columns, transfer girder bearing seats, heavy truss chords, stadium cantilever support columns, and parking garage moment frame members. A913 TMCP shapes eliminate the need for post-rolling heat treatment, providing consistent through-thickness properties from flange tip to web center. Column splice CJP welds and beam-to-column continuity plate fillet welds are the critical weld joints. Available in W14 sections from W14x132 through W14x730, these shapes are the backbone of seismic column design in high-rise construction. The TMCP process creates a fine-grained microstructure throughout the full cross-section, unlike conventional heat-treated shapes that may have property gradients. The H8 path to Category D (32°F all thicknesses) offers significant fabrication cost savings on heavy column splices that would otherwise require 150-225°F preheat under Category B. Column flange thicknesses on W14x455 and heavier sections exceed 3".

Why Preheat Matters at all thicknesses

Category D assigns a flat 32°F minimum at all thicknesses — the steel's crack resistance plus H8 hydrogen control eliminates thickness-based increases.

Other Steels with FCAW (H8) at all thicknesses

Try Different Combinations

Use the interactive preheat calculator to look up any steel, process, and thickness combination from D1.1:2025 Table 5.11.

A913 Gr.50/60/65 Welding Guides