# WeldSci — The Science of Fusion Welding

> An interactive, browser-based simulation tool for understanding the physics and metallurgy of fusion welding (MIG/MAG/MMA/SMAW). Designed for engineers, welding students, and fabricators who want to build intuition for how process parameters drive weld quality.

Source: https://github.com/YellowHapax/Welding
Live: https://yellowhapax.github.io/Welding/
License: Apache 2.0

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## Core Simulation

Three process parameters are adjustable via sliders and drive all downstream calculations:

- **Arc Voltage** (V): 15–35 V
- **Welding Current** (A): 50–350 A
- **Travel Speed** (mm/s): 2–15 mm/s

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## Mathematical Models

All equations are based on empirical welding engineering relationships:

| Quantity | Formula | Units |
|---|---|---|
| Heat Input | Q = (η × V × I) / v, η = 0.8 | J/mm |
| Penetration | P = 0.05 × I / √v | mm |
| Leg Length | Z = 0.06 × V × √I / √v | mm |
| Throat Thickness | a = Z / √2 | mm |
| Reinforcement | R = 0.5 × I / (v × Z) | mm |
| Cooling Time | t₈₅ = Q × 0.005 | s |
| Thermal Profile | T(r,t) = T₀ + (Q·0.8)/(4π·k·α·t) · exp(−r²/(4αt)) | °C |

The thermal profile is Rosenthal-inspired, evaluating three positions: weld centre (r=0), fusion line (r=2 mm), and HAZ at 5 mm.

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## Defect Detection

The tool classifies the current parameter set into one of five weld conditions with engineering rationale:

1. **Good** — balanced penetration, leg length, and bead profile
2. **Lack of Penetration** — current too low or travel speed too high; root unfused
3. **Burn Through** — heat input excessive; arc punches through plate
4. **Undercut** — arc voltage too high relative to current; toes gouged
5. **Excessive Convexity** — travel speed too slow; bead piles up with poor wetting

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## Graphical Views (5 tabbed panels)

1. **45° Fillet** — Fully annotated SVG cross-section. Shows leg length (Z), throat (a), penetration depth, HAZ extent, weld face reinforcement, and weld toes. Adapts geometry and defect indicators live.
2. **Cross-Section** — Butt weld cross-section with animated build sequence (1.3 s ease-in). Shows undercut notches, porosity bubbles, solidification crack, or shallow penetration depending on defect state.
3. **Bead Top-View** — Stack-of-dimes view looking straight down. Blob spacing scales with travel speed; illustrates undercut gouges, burn-through holes, and root seam for lack of penetration.
4. **Zone Map** — Concentric elliptical metallurgical zones: weld metal, fusion zone, coarse-grain HAZ, fine-grain HAZ, base metal. Rosenthal heat glow overlay.
5. **Thermal Profile** — Time-temperature chart (0–3 s) for three radial distances. Phase lines mark T_liquidus (1500°C) and T_solidus (1100°C). t₈₅ cooling time annotated.

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## Defect Presets

Five named parameter sets illustrate the full defect space:
- Optimal Weld: 24 V / 200 A / 5 mm·s⁻¹
- Undercut: 32 V / 200 A / 10 mm·s⁻¹
- Lack of Fusion: 20 V / 100 A / 8 mm·s⁻¹
- Excess Convexity: 20 V / 250 A / 3 mm·s⁻¹
- Burn Through: 28 V / 350 A / 4 mm·s⁻¹

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## Formula Reference Tab

Six key equations with acceptable ranges and reject criteria:

1. Heat Input — Q = (V × I × 60 × η) / (1000 × S) [kJ/mm]
2. Bead Aspect Ratio — AR = W / H
3. Penetration (empirical) — P ∝ I / √v
4. Carbon Equivalent — CE = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15
5. Throat Thickness — a = Z / √2
6. Residual Stress — σ_res ≈ E × α × ΔT

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## Standards Referenced

- AWS D1.1 — Structural Welding Code (Steel)
- ISO 5817 — Welding: Quality Levels for Imperfections
- EN 1993-1-8 — Eurocode 3: Design of Joints

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## Technical Stack

- React 18 (UMD build, no bundler required)
- Babel Standalone 7 (JSX transform in-browser)
- Space Grotesk (headings), IBM Plex Mono (data/labels), Barlow (body)
- Single-file HTML — no build step, no server required, fully offline-capable

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## Intended Audience

Welding engineering students, CWI/CWE candidates, fabrication shop technicians, and anyone building intuition for how voltage, current, and travel speed interact to produce — or destroy — weld quality.

FOR INSTRUCTIONAL USE — Follow applicable WPS/PQR and relevant welding codes for production work.