Introduce
Lean alloy steel refers to the alloy steel with a total amount of alloying elements less than 5%. Lean alloy steel is relative to carbon steel, as well as based on it. In order to improve the performance of steel, people intentionally add one or several alloying elements to the steel. When the amount of alloy added exceeds the general content of the normal production method of carbon steel, the steel is called alloy steel. When the total amount is less than 5%, it’s called Lean alloy steel, ordinary alloy steel is generally less than 3.5%, and the alloy content is between 5-10% is called Key in alloy steel, and those with more than 10% are called High alloy steel.
Application and characteristics
The parts of lean alloy steel structure usually need to go through processes such as forming-welding-post welding heat treatment, which requires the steel to have good process performance. Process performance includes metal weldability, cutting performance, cold and hot workability, heat treatment performance, forgeability, uniform structure stability and large section hardenability. While considering the material cost, the impact of material processing and welding difficulty on the manufacturing cost should also be considered.
Lean alloy steel has been widely used in the manufacture of construction machinery, ships, bridges, high-rise buildings, boilers and pressure vessels, electric power and various vehicles. This is inseparable from its characteristics. (such as: plasticity, toughness, welding performance )
Lean alloy steel properties
Strength
The yield point of the steel structure determines the stress that the structure can withstand without permanent deformation. The minimum yield point of typical carbon structural steel is 235Mpa. The minimum yield point of typical lean alloy high strength steel is 345Mpa. Therefore, according to the proportional relationship of its yield point, the use of lean alloy high strength steel allows the stress to be 1.4 times higher than that of carbon structural steel.
Formability
In order to easily and economically perform hot or cold processing to make various parts of engineering structures, lean alloy high strength steel must have appropriate forming properties. The same as carbon structural steels, lean alloy high strength steels can generally be processed such as shearing, punching and machining. Although its yield point is high, cold bending presses, drawing machines, presses and other equipment used for carbon structural steel forming can be used even if the deformation of the forming operation is quite severe, but some equipment needs to be modified.
Welding performance
Due to the steel structure is often used in the production process of welding technology, it’s very important for lean alloy high strength steels of this type to be welded by arc welding processes that are widely used in the thickness of thin plates and steel strips. It’s also very important that the welded seam of the steel structure produced should have the required strength and toughness, so as to withstand the most unfavorable conditions for the intended use.
Corrosion resistance
When using lean alloy high strength steel, it’s desirable to take advantage of its high strength and use a thinner section. This is not only to save weight but also to be as economical as possible. However, the factor of corrosion must be fully considered. The thinner the steel section, the more attention should be paid to corrosion. The anti-corrosion of any steel structure is generally achieved by applying an anti-corrosion layer on a properly prepared surface and protecting the anti corrosion layer.
Notch toughness
Lean alloy high strength steel types are designed to have fairly good notch toughness for their intended structural use. The applicability of the notch toughness of specific types of lean alloy high strength steel is either based on existing use experience or combined with the impact test results of notched specimens. In order to meet the extremely stringent requirements of certain application, some lean alloy high strength steels produced have excellent notch toughness. For example, controlled hot rolling technology is usually used to produce lean alloy high strength steel plates for the manufacture of welded pipeline steel pipes. Such steel pipes need to meet the requirements of relevant standards for notch toughness.
High manganese carbon steel (Lean alloy steel) | |||||||
Chemical Composition | |||||||
SAE | AISI | UNS Digital System | C | Si | Mn | P,≤ | S, ≤ |
1330 | 1330 | G13300 | 0.28~0.33 | 0.15~0.35 | 1.60~1.90 | 0.035 | 0.040 |
1330H | 1330H | H13300 | 0.27~0.33 | 0.15~0.35 | 1.45~2.05 | 0.035 | 0.040 |
1335 | 1335 | G13350 | 0.33~0.38 | 0.15~0.35 | 1.60~1.90 | 0.035 | 0.040 |
1335H | 1335H | H13350 | 0.32~0.38 | 0.15~0.35 | 1.45~2.05 | 0.035 | 0.040 |
1340 | 1340 | G13400 | 0.38~0.43 | 0.15~0.35 | 1.60~1.90 | 0.035 | 0.040 |
1340H | 1340H | H13400 | 0.37~0.44 | 0.15~0.35 | 1.45~2.05 | 0.035 | 0.040 |
1345 | 1345 | G13450 | 0.43~0.48 | 0.15~0.35 | 1.60~1.90 | 0.035 | 0.040 |
1345H | 1345H | H13450 | 0.42~0.49 | 0.15~0.35 | 1.45~2.05 | 0.035 | 0.040 |
1513 | 1513 | G15130 | 0.10~0.16 | a,b,c,d,e | 1.10~1.40 | 0.040 | 0.050 |
1518 | 1518 | G15180 | 0.15~0.21 | a,b,c,d,e | 1.10~1.40 | 0.040 | 0.050 |
15B21H | 15B21H | H15211 | 0.17~0.24 | 0.15~0.35 | 0.70~1.20 | 0.040 | 0.050 |
1522 | 1522 | G15220 | 0.18~0.24 | b,c,d,e | 1.10~1.40 | 0.040 | 0.050 |
1522H | 1522H | H15220 | 0.17~0.25 | 0.15~0.35 | 1.00~1.50 | 0.040 | 0.050 |
1524 | 1524 | G15240 | 0.19~0.25 | b,c,d,e | 1.35~1.65 | 0.040 | 0.050 |
1524H | 1524H | H15240 | 0.18~0.26 | 0.15~0.35 | 1.25~1.75 | 0.040 | 0.050 |
1525 | 1525 | G15250 | 0.23~0.29 | b,c,d,e | 0.80~1.10 | 0.040 | 0.050 |
1526 | 1526 | G15260 | 0.22~0.29 | b,c,d,e | 1.10~1.40 | 0.040 | 0.050 |
1526H | 1526H | H15260 | 0.21~0.30 | 0.15~0.35 | 1.00~1.50 | 0.040 | 0.050 |
1527 | 1527 | G15270 | 0.22~0.29 | b,c,d,e | 1.20~1.50 | 0.040 | 0.050 |
15B35H | 15B35H | H15351 | 0.31~0.39 | 0.15~0.35 | 0.70~1.20 | 0.040 | 0.050 |
1536 | 1536 | G15360 | 0.30~0.37 | b,c,d,e | 1.20~1.50 | 0.040 | 0.050 |
15B37H | 15B37H | H15371 | 0.30~0.39 | 0.15~0.35 | 1.00~1.50 | 0.040 | 0.050 |
1541 | 1541 | G15410 | 0.36~0.44 | b,c,d,e | 1.35~1.65 | 0.040 | 0.050 |
1541H | 1541H | H15410 | 0.35~0.45 | 0.15~0.35 | 1.25~1.75 | 0.040 | 0.050 |
15B41H | 15B41H | H15411 | 0.35~0.45 | 0.15~0.35 | 1.25~1.75 | 0.040 | 0.050 |
1547 | 1547 | G15470 | 0.43~0.51 | b,c,d,e | 1.35~1.65 | 0.040 | 0.050 |
1548 | 1548 | G15480 | 0.44~0.52 | b,c,d,e | 1.10~1.40 | 0.040 | 0.050 |
15B48H | 15B48H | H15481 | 0.43~0.53 | 0.15~0.35 | 1.00~1.50 | 0.040 | 0.050 |
1551 | 1551 | G15510 | 0.45~0.56 | b,c,d,e | 0.85~1.15 | 0.040 | 0.050 |
1552 | 1552 | G15520 | 0.47~0.55 | b,c,d,e | 1.20~1.50 | 0.040 | 0.050 |
1561 | 1561 | G15610 | 0.55~0.65 | b,c,d,e | 0.75~1.05 | 0.040 | 0.050 |
15B62H | 15B62H | H15621 | 0.54~0.67 | 0.40~0.60 | 1.00~1.50 | 0.040 | 0.050 |
1566 | 1566 | G15660 | 0.60~0.71 | b,c,d,e | 0.85~1.15 | 0.040 | 0.050 |
1572 | 1572 | G15720 | 0.65~0.76 | b,c,d,e | 1.00~1.30 | 0.040 | 0.050 |
Note: a≤0.10%, b=0.10%~0.20%, c=0.15%~0.30%, d=0.20%~0.40%, e=0.30%~0.60%
Mechanical Properties | |||||||
UNS Digital System | ASTM Standard Number | SIZE /mm | State | T.S. /Mpa | Y.S. /Mpa | EL/% (L0=50mm) | Hardness HBS |
G13300 | - | Φ25.4 | WQ+T(204℃,400℉) WQ+T(316℃,600℉) WQ+T(427℃,800℉) WQ+T(538℃,1000℉) WQ+T(649℃,1200℉) | 1600 1427 1158 876 731 | 1455 1282 1034 772 572 | 9 9 15 18 23 | 459 402 335 263 216 |
G13400 | - | Φ25.4 | Normalizing(802℃,1475℉) Annealing(871℃,1600℉) OQ+T(204℃,400℉) OQ+T(316℃,600℉) OQ+T(427℃,800℉) OQ+T(538℃,1000℉) OQ+T(649℃,1200℉) | 703 834 1806 1586 1262 965 800 | 434 558 15931420 1151 827 621 | 25.5 22 11 12 14 17 22 | 207 248 505 453 375 295 252 |
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