What is ASTM A792M?

ASTM A792M Standard Specification for Steel Sheet, 55 % Aluminum-Zinc Alloy-Coated by the Hot-Dip Process.

Hot dipped galvalume steel coil is an alloy steel plate composed of 55% Aluminum, 43.5% Zinc,1.5% Silicon. Hot dipped galvalume steel coil demonstrates stable anti-rust and anti-corrosion ability in various acid and alkaline, humid, and rainy environmental tests. So, galvalume steel coil has a wide range of applications in the industry.


ASTM A792M Equivalent

Chinese standard: GBT 14978

European standard: EN10215

Japanese standard: JIS G3321

What is AFP?

AFP full name is Anti-finger Print, it is means stand of Surface treatment is Anti-Finger print.  

Anti-finger print is a composite coated board obtained after fingerprint-resistant treatment on the surface of a galvalume sheet. Anti-fingerprint steel plate is the first material to pass environmental certification. Because the surface will not leave fingerprints when touched with a clean finger, it is named “Anti-Finger print”. The surface of the Anti-Finger print steel plate is smooth and flat with small tolerances.

ASTM A792M Classification

CS Type A B and CCommercial
FS Forming
DSDeep Drawing

ASTM A792M Chemical Composition

The typical Chemical Composition for CS (Types A, Band C), FS , DS and HTS sheet designations are listed in Below Table (units:%):

CS Type A0.10max.0.60max0.03max.0.035max.
CS Type B0.02 to 0.15max.0.60max0.03max.0.035max.
CS Type C0.08max.0.60max0.10max.0.035max.
FS0.02 to 0.10max.0.50max0.02max.0.030max.
HTS0.02 to 0.15max.0.60max0.04max.0.035max.

The typical Chemical Composition for SS sheet designations are listed in Below Table (units:%):

SS Type 33 [230]0.20max.1.35max0.04max.0.04max.
SS Type 37 [255]0.20max.1.35max0.10max.0.04max.
SS Type 40 [275]0.25max.1.35max0.10max.0.04max.
SS Type 50 Class 1,2,40.25max.1.35max0.20max.0.04max.
SS Type 50 Class 1,2,4 [340 Class 1,2,4]0.25max.1.35max0.04max.0.04max.
SS Type 60 [410]0.25max.1.35max0.04max.0.04max.
SS Type 70 [480]0.25max.1.35max0.04max.0.04max.
SS Type 80 [550] Class 10.20max.1.35max0.04max.0.04max.
SS Type [550]  Class 20.02max.1.35max0.05max.0.02max.
SS Type [550]  Class 30.20max.1.35max0.04max.0.04max.

ASTM A792M Mechanical properties


Tensile test characteristics

Table 1

GradeYield strengthTensile strengthElongation %
CS Type A205/41020Min
CS Type B245/41020Min
CS Type C205/45015Min

NOTE : 1 N/mm2 = 1 MPa

Table 2

GradeYield strengthTensile strengthElongation
SS Type 33 [230]230 Min310 Min20 Min
SS Type 37 [255]255 Min360 Min18 Min
SS Type 40 [275]275 Min380 Min16 Min
SS Type 50 Class 1  [340 Class 1]340 Min450 Min12 Min
SS Type 50 Class 2 [340 Class 2]340 Min12 Min
SS Type 50 Class 4 [340 Class 4]340 Min410 Min12 Min
SS Type 60 [410]410 Min480 Min10 Min
SS Type 70 [480]480 Min550 Min9 Min
SS Type 80 [550] Class 1550 Min570 Min
SS Type [550]  Class 2550 Min570 Min
SS Type [550]  Class 3550 Min570 Min3 Min

NOTE: 1 N/mm2 = 1 MPa

The Coating Mass chart of ASTM A792M

Coating Composition-The 55 % aluminum-zinc coating composition by weight, is nominally 55 % aluminum 1.5 % silicon, and the balance zinc.

The coating applied shall be of equivalent thickness on both surfaces. The coating mass weight chart design is as follows:

ASTM A792M Design Coating Mass Table
Design Coating MassAverage Triple-Spot TestSing-Spot Test

ASTM A792M Surface treatment (temporary surfaceprotection)

Hot-dip galvalume steel products generally receive a surface protection at the producer’s plant as specified as regular surface treatment as below:

Chemical passivation (C)

Chemical passivation may be carried out after coating to protect the surface against humidity and to reduce the risk of the formation of wet storage stains (known as black rust). Chemical passivation may cause slight discoloration of the surface but is not detrimental to the general performance of the product.

Oiling (O)

This treatment also reduces the risk of formation of black rust.
It shall be possible to remove the oil layer with a suitable degreasing solvent which does not adversely affect the coating. Products supplied oiled may require additional lubrication prior to rolling or drawing.

Chemical passivation and oiling(CO)

Agreement may be reached on this combination of surface treatment if increased protection against the formation of black rust is required.


Hot-dip aluminium-zinc coated flat products are only supplied without surface treatment if expressly desired by the purchaser on his own responsibility.In this case, there is an increased risk of early corrosion during transportation and storage.

This article mainly introduces the American standard ASTM A792 technical labeling and common knowledge of galvanized products. I hope this article will help you better understand Hot dip galvalume steel products. If you are looking for a steel supplier or need help, you can contact Witop Steel, we are willing to help you.

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