# Electron beam welding

Electron-beam fusion welding: vacuum routes, joint access and preparation, parameter control, metallurgical limits and qualified acceptance.

Reviewed: 2026-11-01

Tags: processes, welding, beam-welding

A hypothetical **100 kV, 20 mA** beam supplies **2 kW** nominal power. At **10 mm/s** that is **200 J/mm** of nominal beam energy, or **160 J/mm** at **12.5 mm/s**. Verify focus, coupling, actual penetration and the required examination. Beam power and travel speed alone leave the weld geometry and acceptance open.

Accelerated electrons deliver focused heat to a fusion weld. Magnetic optics direct and focus the beam. Concentrated heating can form a keyhole and a narrow, deep fusion zone. [TWI: electron beam welding](https://www.twi-global.com/what-we-do/research-and-technology/technologies/welding-joining-and-cutting/electron-beam-technology/home)

The process often supports single-pass, autogenous joints with low overall heat input and a narrow heat-affected zone. These are route advantages, not promises of zero distortion, universal penetration or unchanged parent properties. Select the joint, alloy condition and inspection requirements before adopting a supplier's best-case capability.

## Identify the vacuum and machine arrangement

Conventional EBW places the assembly in a vacuum chamber, limiting beam scattering by gas and atmospheric contamination. Chamber access, fixtures and controlled motion are part of the manufacturing route. TWI describes equipment spanning different powers and chamber sizes; its penetration figures apply to the described equipment and materials, not every EB machine. [TWI: in-chamber EB welding](https://www.twi-global.com/what-we-do/research-and-technology/technologies/welding-joining-and-cutting/electron-beam-technology/in-chamber-electron-beam-welding)

A complete chamber is not the only arrangement. TWI distinguishes reduced-pressure operation, local static or travelling vacuum seals, and out-of-vacuum welding. These options require their own equipment and process development. “Out of chamber” does not necessarily mean the weld is made at atmospheric pressure: a local seal can maintain a vacuum around the joint. [TWI: out-of-chamber EB welding](https://www.twi-global.com/what-we-do/research-and-technology/technologies/welding-joining-and-cutting/electron-beam-technology/out-of-chamber-electron-beam-welding)

Resolve the following with the supplier:

| Requirement | What to establish |
| --- | --- |
| Assembly envelope | Loading, fixture space, beam path and motion clearance |
| Joint access | Gun approach, rotation/translation and beam exit region |
| Vacuum route | Chamber or local arrangement, compatible assembly contents and cycle assumptions |
| Weld definition | Required fusion depth, location, root condition and start/stop treatment |
| Delivery condition | Heat treatment, machining, cleaning and final examination |

A chamber's internal dimensions are not the usable welding envelope. Sciaky's job-shop sheet separately lists work envelopes and chamber dimensions for its systems, illustrating why both must be checked with the fixture and required motion included. Do not interpret that sheet as proof of current availability or qualification for a particular assembly. [Sciaky: EB welding services, SCI-16-117, revision 14 May 2024](https://www.sciaky.com/images/pdfs/product-sheets/Sciaky-EB-Job-Shop-Services.pdf)

## Material, fit-up and cleanliness

Specify the exact alloys, product forms, heat-treatment conditions and surface treatments on both sides of the joint. For dissimilar materials, require evidence for the actual combination and service; the ability to melt both metals is not sufficient evidence of a suitable weld.

Haynes describes EBW and laser welding of its nickel/cobalt-base alloy families as high-energy-density processes and stresses joint preparation and fit-up. It notes that square butt joints are common and that filler wire, although not normally used, can be added. Autogenous is therefore a common route rather than a definition excluding all filler-assisted EB welds. [Haynes: EBW and LBW guidance](https://haynesintl.com/en/alloys/welding-and-fabrication/welding-and-joining/electron-beam-welding-ebw-and-laser-beam-welding-lbw/)

EB Industries' design guide identifies contaminated assembly and unsuitable machining preparation as avoidable problems, and calls for clean joint surfaces free of machining debris, hydrocarbons and oxidation contaminants. Establish the approved cleaning and handling route before welding. Do not assume chamber evacuation removes solid residues or makes an oily joint acceptable. [EB Industries: *Electron Beam Welding Engineers Design Guide*, cleaning and machining](https://info.ebindustries.com/hubfs/White%20Papers/EBI_Ebeam-DesignGuide-v3.pdf?hsLang=en)

Fit-up and alignment also require control through the depth. TWI warns that residual magnetism, jigging and component consistency affect beam/joint alignment; a centered top bead can conceal a beam that missed the joint below the surface. Appearance alone cannot demonstrate complete fusion. [TWI: beam/joint alignment](https://www.twi-global.com/technical-knowledge/faqs/faq-how-can-i-be-assured-of-good-beam-joint-alignment-following-electron-beam-welding)

## Parameters describe more than beam power

Record the approved accelerating voltage, beam current, focus, travel and any oscillation together with joint geometry, vacuum condition and fixtures. Power or nominal line energy alone cannot describe beam shape, keyhole stability or the resulting thermal cycle. Preserve the equipment program and component configuration used for qualification.

**Original idealized energy example.** Assume a hypothetical steady beam at **100 kV** and **20 mA**, traversing at **10 mm/s**:

- Electrical beam power = 100,000 V × 0.020 A = **2,000 W**.
- Nominal beam energy per travel length = 2,000 / 10 = **200 J/mm**.
- Increasing speed to 12.5 mm/s at unchanged power gives **160 J/mm**, a **20% reduction**.

A 25% speed increase reduces nominal energy per length by 20%. The model excludes coupling, focus, oscillation, transients and thermal losses.

Rapid solidification and narrow geometry do not remove metallurgical concerns. Haynes identifies porosity from gas that cannot readily escape a deep pool and liquation cracking near the nail-head region for its alloy context. Beam motion and travel changes can influence these effects, but their guidance is not a universal corrective setting. Qualify the thermal response and any required postweld treatment for the actual alloy and condition. [Haynes: porosity and cracking considerations](https://haynesintl.com/en/alloys/welding-and-fabrication/welding-and-joining/electron-beam-welding-ebw-and-laser-beam-welding-lbw/)

## Qualification and finished-weld acceptance

ISO **15614-11:2025**, edition 2, October 2025, **corrected May 2026**, specifies qualification testing of welding procedure specifications for electron and laser beam welding. Its scope includes metallic materials, new production and repair. Use the applicable qualification and contractual requirements; the public scope does not itself qualify a supplier's proposed schedule. [ISO 15614-11:2025](https://www.iso.org/standard/81785.html)

ISO **13919-1:2019**, edition 2, October 2019, confirmed in 2026, addresses imperfection quality levels for steel, nickel, titanium and their alloys at thicknesses of at least 0.5 mm. Level B has the highest requirements among its three levels. The standard explicitly distinguishes production quality from fitness for purpose, excludes metallurgical properties such as hardness/grain size, and does not supply complete NDT detection/sizing criteria. Specify the level and any additional examination or service requirements before production. [ISO 13919-1:2019](https://www.iso.org/standard/75514.html)

Agree examination methods, accessible regions, sampling, acceptance and repair disposition. Separate weld geometry and imperfections from leak tightness, dimensional stability, strength or fatigue performance. Record the final inspection state after any machining or heat treatment. Process monitoring supports reproducibility; it does not automatically replace the specified examination.

## Source versions

Reviewed 2026-11-01. ISO editions and correction are identified above. Sciaky's actual footer reads SCI-16-117 REV 5/14/2024 and ©2024. No separate technical issue date was verified for the cited TWI/Haynes pages or EB Industries guide; website years and filenames are not treated as editions. The energy example and manufacturing-handoff recommendations are original.

## Related reference

[Welding methods](index.md)