Post-Production – Weld Qualities

< Problem > Impossible to evaluate the weld quality at Designing stage before producing real welds and difficult to predict weld defects.

< Solution > Predict the weld nugget formation, hardness and micro structures, cracking risks and weld strengths by simulations.

< Principle > To ensure weld quality in terms of weld sizes, weld strengths and weld material properties around the weld without defect.

Evaluate Weld Quality at a Glace

weld quality radar chart

A single weld can meet nugget diameter requirements yet still suffer from expulsion, weak joining, excessive indentation, or poor fusion quality.

The Weld Quality Radar Chart provides a comprehensive visual assessment of weld performance, enabling engineers to evaluate multiple quality aspects simultaneously.

Six Key Weld Qualities

Weld quality can be represented by various evaluation criteria. To predict the overall weld quality of each completed weld, SORPASĀ® 2D.welding selected six key quality factors: splash severity, nugget diameter, nugget penetration, surface indentation, LME cracking risk, and HAZ softening.

nugget cross section view six key weld qualities

1. Splash severity

Splash severity reflects process stability during welding. Excessive splash is often associated with overheating conditions, leading to defective welds, cosmetic problems, and safety issues for workers that can negatively affect production reliability.

2. Nugget diameter

Weld nugget diameter is a primary indicator of weld quality and joint strength. In resistance spot welding, it is often used as the fundamental criterion for optimizing welding parameters such as weld time, current, and force.

3. Nugget penetration

Weld nugget penetration indicates how effectively fusion is achieved through the material stack-up. It is particularly important in multi-sheet welding, where sufficient penetration into the thinnest sheet is critical for joint reliability.

4. Surface indentation

Surface indentation reflects the degree of surface deformation caused by electrode loading during welding. It is commonly monitored to balance weld performance, cosmetic quality, and material thinning.

5. LME craking risk

LME (Liquid Metal Embrittlement) cracking can reduce weld durability and fatigue performance by creating surface defects. Minimizing LME susceptibility is therefore an important objective when optimizing spot welding parameters for Zn-coated AHSS.

6. Softening in HAZ

Hardness distribution after welding is an important indicator of metallurgical changes within the weld and heat-affected zone (HAZ). Excessive softening can reduce load-carrying capability, making hardness evaluation valuable for optimizing the cooling rate.

From Individual Metrics
to a Single Quality Score

To simplify weld assessment, SORPASĀ® combines six weld quality scores into a unified Weld Quality Score, allowing quick comparison of welding schedules and process conditions. This Quality ScoreĀ classifies the final weld quality into five grades: Excellent > Good > Fair > Poor > Defective.

Hardness Distribution

Hardness distribution represents the final hardness state of the weld after all phase transformations are completed. It provides insight into the metallurgical characteristics of the weld nugget, HAZ, and surrounding base material.

Hardness Curve

The hardness curve shows the hardness variation across the weld section and is commonly used to identify HAZ softening. It serves as an important indicator of the metallurgical effects of welding conditions and post-weld cooling behavior.

Reference publication

Weld Strength

Weld strength ultimately determines the performance of a weld joint. Although it is not one of the six quality indicators evaluated in SORPASĀ® 2D.Welding, the software predicts the expected weld strength from the final weld characteristics.

To further investigate joint behavior under mechanical loading, users can extend the analysis in SORPASĀ® 3D.Testing, where virtual testing simulations provide deeper insight into strength and failure mechanisms.

SORPASĀ® 3D.testing
SORPASĀ® 3D.welding
SORPASĀ® 2D.welding