AWS D1.1 · Table 6.1 · Criterion 4

Weld Profile Per Figure 5.4 — Convexity, Concavity & Overlap

AWS D1.1 specifies acceptable limits for weld bead shape: convex (bulging), concave (dished), and overlap (cold lap). Figure 5.4 provides the acceptance limits based on weld type and base metal thickness.

Weld Profile Terminology

The weld profile is the cross-sectional shape of the bead as viewed from the side. Three characteristics are measured or observed:

Convexity — The extent to which the weld face rises above the legs (toes). Measured as the perpendicular distance from the straightline through the toes to the highest point of the weld face.
Concavity — A dished or inward-curving profile. The weld face dips below the weld legs. Reduces weld cross-sectional area and strength.
Overlap (cold lap) — Weld metal extends past the toe and laps over the base metal without fusing to it. Always rejected regardless of extent.

Weld Profile Shapes — Fillet & Groove

CONVEX (Good) CONCAVE (Thin) OVERLAP (Reject) ┌───────────────────────────────────────────────────────┐ │ /\ / \ ╱╲ │ │ / \ (OK) / \ (thin) / ╲━ │ │ ══════════════ ════════════ ════════════ │ │ Reinforced Undersized Lap overlap │ └───────────────────────────────────────────────────────┘

AWS D1.1 Table 6.1 Acceptance Criterion

Criterion 4: Weld Profile Per Figure 5.4

Acceptance Limits (per AWS D1.1 Figure 5.4):

Convexity — Generally acceptable up to 1/8" (0.125") for fillet welds. Groove weld convexity limits depend on base metal thickness (Figure 5.4 specific).
Concavity — Concave welds are acceptable up to 1/16" (0.0625") for fillet welds, provided the weld cross-section meets the required leg size. For groove welds, concavity reduces effective area and is restricted per WPS.
Overlap (Cold Lap) — ALWAYS REJECTED, regardless of size. Any visible overlap of weld metal onto the base metal without fusion is a rejection.

Reference Document: Consult AWS D1.1 Figure 5.4 for specific convexity and concavity limits based on weld geometry and base metal thickness.

Common Weld Profile Defects & Causes

Excessive convexity — Too high amperage, slow travel speed, or poor welder technique. Weld puddle too large and domed. Weakens toe fusion and increases shrinkage stress.
Concave profile (underfill) — Low amperage, high travel speed, or thin root opening allows the weld to be undersized. May meet profile limits but reduces joint strength.
Overlap / cold lap — Weld bead drifts away from the joint line and laps the base metal. Caused by poor welder control, wrong angle, or excessive lateral movement.
Inconsistent profile — Travel speed or amperage varies, producing a wavy or irregular bead. Some sections may exceed limits while others meet them.

How to Inspect & Document for the Report

Visual measurement with profile gauge — Use a weld profile (step) gauge to measure convexity and concavity at several points along the bead. Compare to AWS Figure 5.4 limits.
Magnified inspection for overlap — Look for weld bead extending beyond the base metal surface without fusion. Use 10x glass if needed. Any overlap is a rejection.
Document measurements — Record convexity/concavity values (in inches or mm) at 3-5 points along the weld. Note any areas exceeding limits.
Cross-section for verification — On critical welds, cut a sample perpendicular to the bead and measure actual cross-sectional area. Compare to WPS specification.
Mark defects clearly — Overlap: REJECT. Excessive convexity/concavity: document measurements and decision per Figure 5.4.

CWI Inspection Tips

AWS Figure 5.4 is the source of truth. Always reference it for specific acceptance limits. Don't apply arbitrary thresholds.
Overlap defects are most concerning because they introduce unbonded areas that can initiate cracks under stress. Never accept any overlap.
Excessive convexity (doming) may be visually obvious but within Figure 5.4 limits. It indicates lack of toe fusion control; inspect toe fusion separately.
Concave welds that are thin (underfilled) may pass profile inspection but fail weld size measurement. Always check that weld leg size matches WPS specification.

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