Corrosion Resistance of Steels, Nickel Alloys, and Zinc in Aqueous Media

Waste Water, Seawater, Drinking Water, High-Purity Water

Michael Schütze, Marcel Roche, Roman Bender

• Publisher: Wiley-VCH
• Year: 2015
• Print ISBN:
  9783527340699
• eBook ISBN:
  9783527698356
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Industrial & Technical Chemistry

This handbook is derived from the online reference "Corrosion Handbook", bringing together the relevant information about corrosion protection and prevention for steels, one of the most widely used materials. It provides comprehensive information, including tabulated data and references, on the corrosion properties of the following materials:
Unalloyed steels and cast steel, unalloyed cast iron, high-alloy cast iron, high-silicon cast iron, structural steels with up to 12% chromium, ferritic chromium steels with more than 12% chromium, ferritic-austenitic steels with more than 12% chromium, high-alloy multiphase steels, ferritic/perlitic-martensitic steels, ferritic-austenitic steels/duplex steels, austenitic chromium-nickel steels, austenitic chromium-nickel-molybdenum steels, austenitic chromium-nickel steels with special alloying additions, special iron-based alloys, and zinc.
The following corrosive media are considered: Seawater, brackish water, industrial waste water, municipal waste water, drinking water, high-purity water.

Seawater

Author: P. Drodten / Editor: R. Bender

Introduction

Table of contents

1. V 1 Marine atmosphere, splash, tidal and immersion zones
2. V 2 Seawater corrosion parameters.
   1. V 2.1 Salt content
   2. V 2.3 Solute gases
3. V 3 Corrosion types
   1. V 3.1 Uniform surface corrosion and shallow pit corrosion
   2. V 3.2 Pitting corrosion and crevice corrosion
   3. V 3.3 Stress corrosion cracking
   4. V 3.4 Corrosion fatigue
   5. V 3.5 Contact corrosion
   6. V 3.6 Current-induced corrosion types

V 1 Marine atmosphere, splash, tidal and immersion zones

Over 70% of the surface of the earth is covered with seawater. This makes seawater the most widespread corrosive medium next to the atmosphere. Most metals, alloys and construction materials are corroded by seawater and marine atmospheres. The conditions of exposure are the main parameters determining the behaviour of the different materials. Exposure is classified roughly into four zones:

• marine atmosphere
• splash zone (SZ)
• tidal zone (TZ)
• immersion zone (IZ).

Atmospheric corrosion is not grouped with reactions in gases, but is rather an instance of electrolytic corrosion that occurs only when a film of liquid, moist deposits or corrosion products have formed on the metal surface. The rate of corrosion in seawater is determined mainly by the amount of oxygen that reaches the cathode, whereby the electrolyte resistance is of no consequence due to the large cross-section and good conductivity. In atmospheric corrosion, on the other hand, the relatively high level of electrical resistance of the thin film of moisture is a major determinant of the corrosion rate, since oxygen access is practically unhindered over the short diffusion pathways involved. Due to the good conductivity of the medium, the anode and cathode of a corrosion cell in seawater can be some distance apart. Such macroelements are frequently found on sheet piling or submerged surfaces of ships and can be made use of in applications of cathodic corrosion protection (CCP). In atmospheric corrosion, the elements act over very short distances only, rendering cathodic protection practically ineffective.

At an air temperature of 283 K (10 °C), an air pressure of 1,013 hPa and 60% relative humidity the water content is around 5.7 g/m³. At 303 K (30 °C) and relative humidity of 100%, the water content rises to 31.4 g/m³. The water film that condenses when the temperature drops or on relatively cold surfaces is always saturated with oxygen. Whereas corrosive action in a non-marine atmosphere is mainly determined by moisture content and potential industrial contaminations, the marine atmosphere is characterised by a raised content of salt particles carried on the wind from the sea spray. Since the salt particles deposited on the metal surface, or aerosols containing salt, also contain hygroscopic components, e.g. c...

Table of contents

• Cover
• Table of Contents
• Title
• Editors
• Copyright
• Preface
• How to use the Handbook
• Warranty disclaimer
• High Purity Water
• Drinking Water
• Seawater
• Waste Water (Municipal)
• Waste Water (Industrial)
• Key to materials compositions
• Index of materials
• Subject index
• End User License Agreement