Common Alloy Structure Steels and Their Chemical Composition
Common alloy structure steels are widely used for building structures, vehicles and other mechanical parts, bridges, machine bodies and components, ships, oil and gas platforms and other structural components. These steels have been specifically developed to provide structural performance in various conditions and are selected based on their special requirements, such as strength and toughness, weldability, formability, improved corrosion resistance and weather resistance, hardenability and applications. The main common alloy structure steels can be divided into low-alloy steel grades, enhanced steels and stainless steels.
Low-alloy steels are steels which contain alloying elements that have a small percentage of the composition. These alloying additions of 1-5% are typically a combination of manganese, chromium, vanadium, tungsten, molybdenum or nickel, and must be heat treated or normalized. The advantages of using such steels are increased strength, hardness and improved corrosion resistance. Common low-alloy steel grades are shown in the table below, along with their chemical composition:
Grade C Si Mn P S Cr Ni Mo V W Cu
40Mn2 0.37-0.44 ≤ 0.17 0.60-0.90 ≤ 0.035 ≤ 0.035 - - - - - -
45Mn2 0.42-0.48 ≤ 0.17 0.70-1.00 ≤ 0.035 ≤ 0.035 - - - - - -
50Mn2V 0.44-0.51 ≤ 0.17 0.90-1.20 ≤ 0.035 ≤ 0.035 0.17-0.37 - - 0.10-0.15 - -
20Mn2 0.17-0.23 ≤ 0.17 1.00-1.30 ≤ 0.035 ≤ 0.035 - - - - - -
30Mn2 0.26-0.34 ≤ 0.17 1.10-1.40 ≤ 0.035 ≤ 0.035 - - - - - -
28Mn6 0.27-0.33 ≤ 0.30 1.30-1.60 ≤ 0.035 ≤ 0.035 0.80-1.10 0.30-0.50 - - - -
27MnCrB5 0.26-0.32 ≤ 0.25 1.00-1.25 ≤ 0.030 ≤ 0.030 0.80-1.15 - - 0.15-0.30 0.15-0.25 -
27MnCrB5-2 0.26-0.32 ≤ 0.25 1.15-1.40 ≤ 0.030 ≤ 0.030 0.80-1.15 - - 0.15-0.30 0.15-0.25 -
38MnB5 0.33-0.39 ≤ 0.30 1.20-1.50 ≤ 0.030 ≤ 0.030 0.80-1.10 - - 0.20-0.30 - -
Enhanced steels are quenched and tempered steels. They are made with high-strength, low-alloy elements. Enhanced steels have greater strength, heat resistance and corrosion resistance. Common enhanced steels, along with their chemical compositions, are listed in the table below:
Grade C Si Mn P S Cr Ni Mo Cu V W Nb
08-20Cr2MoV 0.17-0.23 ≤ 0.17 1.10-1.40 ≤ 0.030 ≤ 0.030 0.17-0.24 ≤ 0.30 0.85-1.15 - - 0.06-0.10 -
08Mn2V 0.17-0.23 ≤ 0.17 0.90-1.20 ≤ 0.030 ≤ 0.030 0.17-0.24 - 0.40-0.60 - 0.07-0.12 -
28Mn6V0.27-0.33 ≤ 0.30 1.30-1.60 ≤ 0.035 ≤ 0.035 0.80-1.10 - 0.15-0.30 - 0.05-0.10 0.05-0.15
20MnMoB 0.17-0.23 ≤ 0.17 1.30-1.80 ≤ 0.030 ≤ 0.030 0.17-0.24 - 0.50-0.70 0.30-0.50 0.05-0.15 0.04-0.10 0.08-0.12
18Mn2MoNbV 0.17-0.23 ≤ 0.17 1.30-1.80 ≤ 0.035 ≤ 0.035 0.17-0.24 0.2-0.7 0.50-0.70 0.15-0.25 0.04-0.10 0.07-0.12 0.04-0.10
Stainless steels are stainless steels, or stainless alloys, which contain at least 10.5% chromium. They have excellent corrosion resistance, strength and formability, making them essential for a wide range of applications. The chemical composition of popular stainless steel grades is shown in the table below:
Grade C Si Mn P S Cr Ni Mo Cu V
1Cr18Ni9Ti 0.07-0.13 ≤ 0.75 ≤ 2.00 ≤ 0.035 ≤ 0.030 16.0-18.0 8.0-10.5 - - -
00Cr17Ni14Mo2 0.07-0.12 ≤ 0.75 ≤ 2.00 ≤ 0.035 ≤ 0.030 16.0-18.0 7.0-9.0 2.0-3.0 - -
00Cr17Ni14Mo2 0.07-0.12 ≤ 0.75 ≤ 2.00 ≤ 0.035 ≤ 0.030 16.0-18.0 7.0-9.0 2.0-3.0 - -
04Cr17Ni12Mo2 0.03-0.08 ≤ 0.75 ≤ 2.00 ≤ 0.035 ≤ 0.030 16.0-18.0 8.5-11.5 2.0-3.0 - -
Common alloy structure steels are useful in various construction and engineering applications, ranging from bridges to vehicles. Such steels are normally divided into low-alloy, enhanced and stainless steel grades, each of which have different chemical compositions. Low-alloy steels generally contain up to 5% alloying elements, while enhanced steels contain addition high-strength elements and corrosion-resistant elements. Stainless steels contain at least 10.5% chromium and have excellent corrosion resistance and strength.
