ISO 9224:2012 pdf download.Corrosion of metals and alloys — Corrosivity of atmospheres-Guiding values for the corrosivity categories.
Steels that have been hardened to produce tensile strengths above about 1 000 MPa can suffer environmentally assisted cracking as a result of atmospheric corrosion.
6.2 Zinc materials
Zinc alloys also vary significantly in their atmospheric performance. The BI values in Table 2 are obtained from commercially pure zmc alloys, but other zinc alloys have shown higher b values in atmospl’ienc exposures(31. Electroplated zinc coatings, mechanically plated zinc coatings, and hot-dipped zinc coatings all have urwque behaviours, and using Equation (1) with the Bi or B2 values might not accurately predict their performance. Zinc materials are particularty susceptible to attack from sulfur dioxide, and environments with high levels of this gas (sulfur dioxide range P3) probably corrode at higher rates than predicted by Equation (1). In these cases, it is prudent to assume a corrosion rate that is linear with time, that is the h value is 1,0.
NOTE For more information on the use of znc coatings br corrosion protection, see ISO 14713-1
6.3 Copper alloys
Copper alloys, such as brasses (i.e. copper-zinc alloys), bronzes (i.e. copper-tin alloys), nickel silvers (i.e. copper alloys with zinc and nickel contents) and cupronickels. have atmospheric corrosion rates similar to. or somewhat less than, pure coppert4151, The Bi and B2 values in Table 2 are adequate for all of these materials. Brasses with zinc contents above about 20 % can expenence dezinciflcation in aggressive atmospheres. Two-phase brasses are most susceptible to this type of attack. It should also be noted that strain-hardened copper alloys can experience environmental cracking in natural atmospheres if their degree of strain hardening is high enough.
6.2 Zinc materials
Zinc alloys also vary significantly in their atmospheric performance. The BI values in Table 2 are obtained from commercially pure zmc alloys, but other zinc alloys have shown higher b values in atmospl’ienc exposures(31. Electroplated zinc coatings, mechanically plated zinc coatings, and hot-dipped zinc coatings all have urwque behaviours, and using Equation (1) with the Bi or B2 values might not accurately predict their performance. Zinc materials are particularty susceptible to attack from sulfur dioxide, and environments with high levels of this gas (sulfur dioxide range P3) probably corrode at higher rates than predicted by Equation (1). In these cases, it is prudent to assume a corrosion rate that is linear with time, that is the h value is 1,0.
NOTE For more information on the use of znc coatings br corrosion protection, see ISO 14713-1
6.3 Copper alloys
Copper alloys, such as brasses (i.e. copper-zinc alloys), bronzes (i.e. copper-tin alloys), nickel silvers (i.e. copper alloys with zinc and nickel contents) and cupronickels. have atmospheric corrosion rates similar to. or somewhat less than, pure coppert4151, The Bi and B2 values in Table 2 are adequate for all of these materials. Brasses with zinc contents above about 20 % can expenence dezinciflcation in aggressive atmospheres. Two-phase brasses are most susceptible to this type of attack. It should also be noted that strain-hardened copper alloys can experience environmental cracking in natural atmospheres if their degree of strain hardening is high enough.
