Lesson 8: Repair welding of corrosion-resistant materials

In this lesson, we will explore the welding techniques and considerations when repairing corrosion-resistant materials commonly used in industries like food processing, pharmaceuticals, and chemical processing.


  • Corrosion-resistant steels find widespread use in industries where protection against corrosion is critical.
  • The corrosion resistance of a material is determined by its ability to withstand corrosion without significant surface loss (typically less than 0.1 mm per year).

Characteristics of Corrosion-Resistant Materials

  • Corrosion-resistant materials have specific characteristics:
    • A uniformly sealed solid CrO layer covers the surface.
    • The internal fabric structure is either homogeneous austenitic or ferritic.

Types of Corrosion-Resistant Materials

  • Ferritic
    • Low carbon content (max 0.1% C) and chromium content (12-18% Cr).
    • Welding technology for ferritic materials requires specific preparation and preheating techniques.
  • Martensitic
    • Martensitic materials are used in applications like shafts, pins, knives, cutting tools, instruments, and turbine blades.
    • Two types based on carbon content:
      • Low carbon content (0.16-0.25% C) martensitic materials.
      • High carbon content (>0.25% C) martensitic materials.
    • Welding and post-welding treatments vary based on carbon content.
  • Austenitic
    • Austenitic materials have specific chromium (Cr), nickel (Ni), and carbon (C) content.
    • They are commonly used in industries demanding high corrosion resistance.

Welding Techniques by Material Type

  • Ferritic materials (KO1-KO6) require preheating and specific welding processes.
  • Welding of martensitic materials (KO11-KO16) depends on carbon content and involves preheating and tempering.
  • Austenitic materials (C 0.03-0.07%, 18-30% Cr, 8-30% Ni) have their own unique welding considerations.

Welding Technology for Ferritic Materials

  • Preparation includes grinding out defects.
  • Preheating to 200-350°C is essential to prevent grain hardening and cracking.
  • Argon Arc Welding (AWI) for root welds, electrode-coated welding for filler welds.
  • Air cooling and post-treatment (heating and cooling) are required.

Welding of Martensitic Materials

  • Welding technique varies based on carbon content.
  • Preheating and immediate tempering at specific temperatures are crucial to achieve desired properties.


  • Repair welding of corrosion-resistant materials demands careful consideration of material type, carbon content, and specific welding techniques.
  • Adherence to recommended procedures ensures the preservation of corrosion resistance properties.

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