Corrosion of metals and alloys — Method for estimating the atmospheric corrosion resistance of low-alloy steels
1 Scope
This document gives three methods for estimating the atmospheric corrosion resistance of low-alloy steels. Method 1 is a prediction method based on short-term corrosion data of steels; method 2 is a prediction method based on chemical composition of steels; and method 3 is a prediction method based on environmental factors and chemical composition of steels.
Method 1 in this document is applicable to the estimation of long-term corrosion losses of specific grades of low-alloy steels using available short-term atmospheric corrosion data in different environments; method 2 is applicable to the estimation of relative corrosion resistance of low-alloy steels based on atmospheric corrosion resistance index (I); and method 3 is applicable to the estimation of corrosion losses of low-alloy steels at different times in different environments.
Note: These three methods are calculated based on the test data of exposed samples of flat bare steels. The actual atmospheric corrosion rate is much higher when the low-alloy steel is wet for a long time or is severely eroded by some salts or other corrosive chemicals.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute indispensable requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 14165 Corrosion of metals and alloys — Atmospheric corrosion testing — General requirements for field tests
GB/T 16545 Corrosion of metals and alloys — Removal of corrosion products from corrosion test specimens
3 Terms and definitions
For the purposes of this document, the following term and definition apply.
3.1
low-alloy steel
material with Fe as the main element, the carbon content of generally less than 2% and the total mass fraction of other alloying elements of 1.0%~5.0%
Note: Most low-alloy weathering steels contain chromium and copper, and some are also added with silicon, nickel, phosphorus, or other alloying elements that can improve their weathering resistance
3.2
atmospheric corrosion resistance index
I
value representing the relative corrosion resistance of low-alloy steel calculated by its chemical composition
4 Procedure
4.1 General
Atmospheric corrosion data shall be obtained according to GB/T 14165 test. Specimens shall be prepared, cleaned, and estimated in accordance with GB/T 16545.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Procedure
5 Report
Annex A (Informative) Method 1: Example of prediction method based on short-term corrosion data of steels
Annex B (Informative) Method 2: Examples of prediction method based on chemical composition of steels
Annex C (Informative) Method 3: Examples of prediction method based on environmental factors and chemical composition of steels
