ISO 18278-1:2022

Overview - ISO 18278-1:2022 (Resistance welding - Weldability)

ISO 18278-1:2022 specifies general requirements and test procedures for assessing the weldability of metallic materials using resistance spot, seam and projection welding. The standard describes how to evaluate the generic weldability of uncoated and coated metals to support:

• comparison of metallurgical weldability between materials,
• assessment of different component designs (stack-ups, projections, geometry),
• investigation of welding parameter effects (current, time, electrode force, pulse schedules), and
• comparison of resistance welding equipment performance.

This part introduces key concepts such as welding current range, weldability lobe, and practical test sequences to quantify weld formation, electrode life, and weld performance.

Key topics and technical requirements

• Weldability definitions and scope: distinguishes metallurgical, operative and constructional weldability and establishes criteria for evaluation.
• Essential tests and procedures: includes the welding current range test, electrode life test, and weldability lobe test. Test selection depends on whether the goal is material comparison, design validation or equipment benchmarking.
• Evaluation of weld properties: prescribes destructive test methods and property assessments such as tensile-shear, mechanized peel, cross-tension, macro-section inspection and hardness testing to confirm weld integrity.
• Preparation and measurement: requirements for welding equipment setup, electrode selection and measurement of key parameters (welding current, electrode force, weld time/speed).
• Acceptance criteria and reporting: guidance on documenting test conditions and results, including characterization of the weldability lobe and electrode wear/life metrics.
• Weldability lobe concept: graphical method to represent acceptable combinations of current, time (or speed for seam welding) and force that produce adequate welds without expulsion or splash.

Practical applications and target users

Who uses ISO 18278-1:2022:

• Welding engineers and process developers optimizing resistance welding procedures.
• Material scientists comparing weldability of coated and uncoated steels, aluminum and other metallic groups.
• Product designers assessing constructional weldability for assemblies and joint designs.
• Manufacturing/QA teams validating production settings and electrode maintenance schedules.
• Equipment manufacturers and test laboratories performing performance comparisons and procedure qualification.

Typical applications:

• Establishing robust production welding windows (current/time/force).
• Selecting appropriate electrode configurations and projection designs.
• Investigating process changes (pulse welding, current stepping) and their effect on weld quality.
• Benchmarking welding machines and developing qualification test reports.

Related standards

Normative references include procedures and test methods such as ISO 669, ISO 14273, ISO 14270, ISO 14271, ISO 14272, ISO 15609-5, ISO 15614-12, ISO 16432, ISO 17677-1, and ISO/TR 581, among others - useful for detailed specimen dimensions, hardness testing and welding procedure qualification.

Keywords: ISO 18278-1:2022, resistance welding, weldability, weldability lobe, spot welding, seam welding, projection welding, welding current range, electrode life, welding procedure.