Failure in materials doesn’t always come with warning signs. Often, it begins invisibly — a microcrack here, a corroded spot there — until the damage accumulates enough to cause a shutdown, injury, or worse.

Whether you work in engineering, maintenance, or procurement, understanding why materials fail is key to preventing costly outcomes. In this article, we explore the most common causes of material failure, what they look like, and how you can stay ahead of them.

 

  1. Corrosion

Corrosion is a progressive and often localised chemical or electrochemical deterioration of materials—primarily metals. It’s driven by environmental exposure to oxygen, chlorides, moisture, or acids. It may present as uniform surface rust or as pitting, crevice corrosion, or stress corrosion cracking (SCC), depending on the conditions and alloy used.

In New Zealand, proximity to the ocean, high humidity, and geothermal activity can accelerate corrosion — even for “corrosion-resistant” materials like stainless steels.

Common symptoms: Discolouration, roughened surfaces, loss of thickness, or structural weakening.

What you can do: Select appropriate grades of stainless steel (e.g. 316 vs 304), apply surface treatments, conduct regular inspections, and consider coatings or sacrificial anodes in marine or buried applications.

 

 

  1. Fatigue

Fatigue failure results from repeated loading and unloading cycles — even when those cycles remain below the yield strength of the material. Over time, microcracks initiate (often at stress concentrations like weld toes or bolt holes) and propagate until sudden failure occurs.

Fatigue is often missed because the initial stages produce no visual indicators. Cracks typically initiate at the surface and grow inward.

Common sectors affected: Transport (trucks, rails, ships), infrastructure (bridges), and high-pressure systems.

  1. Improper Material Selection

Even the best design can fail if the wrong material is selected. Failures may arise from using materials with inadequate mechanical strength, poor corrosion resistance, or unsuitable thermal behaviour. It’s often a result of prioritising cost over performance — a short-term saving that leads to long-term risk.

Examples include:

  • Aluminium used where high cyclic loading is present (fatigue)
  • Mild steel where corrosion resistance is critical
  • Martensitic stainless where notch toughness is needed

What you can do: Engage material engineers during design reviews, request supplier MTCs (Material Test Certificates), and factor in real operating environments — not just lab specs.

 

  1. Manufacturing Defects

Defects introduced during casting, welding, machining, or heat treatment can severely reduce service life. Inclusions, voids, porosity, hard or brittle microstructures, or improper grain orientation can act as crack initiation points — especially when under stress or in corrosive environments.

Real-world issues we’ve seen include:

  • Welds with slag inclusions and lack of fusion
  • Castings with internal shrinkage cavities
  • Improper tempering leading to brittle failures

What you can do: Enforce quality control standards like ISO 5817, AS/NZS 1554, or ISO 17637. Apply NDT like visual inspection, dye penetrant, or radiography during fabrication and perform sample destructive testing where needed.

  1. Misuse or Overloading

Many failures come down to how components are used in the field. Excessive loads, temperature excursions, vibration, chemical exposure, or even incorrect installation can push materials beyond their intended limits.

Typical signs: Plastic deformation, warping, surface fractures, or coating delamination.

What you can do: Provide operational training, define safe working limits, use sensors or load monitoring devices in critical systems, and assess components after any incident or overload event.

What to Take Away

Material failure isn’t random — it’s a signal. A crack, a stain, a shift in shape — they all mean something is changing. The key is knowing how to interpret those signals before they turn into failures.

At our lab, we work with clients throughout New Zealand to:

  • Investigate failed components
  • Test new materials and welds
  • Recommend preventative strategies
  • Provide non-destructive and destructive testing services

Curious about how we can help?
[Contact our lab here] — let’s make sure your material doesn’t become your weakest link.