High strength low alloy steel
ISO/TR 15608 Material Group 3.1: Quenched and tempered (QT) fine-grain high strength low alloy steel with a specific minimum yield strength 360 < ReH ≤ 690 N/mm2.
What is the quenched and tempering (QT) process of high strength low alloy steel?
Quenching and tempering is a heat-treatment method for high strength low alloy steel. Quenching and tempering consists of a two-stage heat-treatment process.
Stage 1 includes hardening, in which the plate is austenitised to approximately 900°C and then quickly cooled. The material is water-quenched in a quench unit, in which the plate is clamped to avoid warpage.
Stage 2 consists of tempering the material to obtain the desired material properties. Quenching and tempering achieves an extremely fine-grained and homogeneous microstructure. Quenched and tempered steel is characterised by high strength and good ductility.
Weldability of high strength low alloy steels ISO/TR 15608 Material Group 3.1
The high-strength tempered materials are generally weldable. However, certain requirements must be met during welding with regard to heat input and controlled cooling in the heat-affected zone and the use of hydrogen-reduced weld metal.
Normally, materials up to a wall thickness of 15 – 20 mm can usually be welded without preheating.
When welding high strength steels, it should be noticed that that a tempering effect occurs due to the heat input during welding, which influences the properties of the base material. The temperature-time cycles during welding have a significant effect on the mechanical properties of a welded joint and the heat effect zones. It is understood, that the t8/5-time is sufficient to describe the temperature-time characteristics. t8/5 is the cooling time from 800°C to 500°C and describes the cooling conditions of an individual weld pass for the weld metal and the corresponding heat affected zone (HAZ). t8/5 depends on the heat input during welding, the plate temperature (or interpass temperature), the shape factor (geometry) and on plate thickness if two dimensional heat flow occurs which is generally the case for thin plates. To achieve satisfactory weld metal properties the welding parameters must be limited with increasing yield strength. For example acceptable properties for an P690QL1 steel are normally obtained with cooling times between 5 s and 20 s. For lower cooling times the hardness of the heat affected zone may exceed limiting values with the risk of introducing cracks.
The hydrogen content of the consumables H2 has a significant influence on the preheating temperature. In order to reduce the risk of hydrogen-induced cracking the preheating temperature must be increased with growing hydrogen content.
Flame straightening of high strength low alloy steels ISO/TR 15608 Material Group 3.1
The maximum recommended temperatures for Flame straightening is usually < 550°C for quenched and tempered steels.
Quenched and tempered (QT) fine-grain steels with a specific minimum yield strength ReH > 690 N/mm2: see Group 3.2
Typical materials in ISO/TR 15608 material group 3.1
| Name/Grad | Number | Standard | Product | Remarks/Trade Mark |
|---|---|---|---|---|
| G20Mn5 | 1.5419 | EN 10213 | Cast | EN 13445-2 & EN 13480-2 |
| 20MnMoNi4-5 | 1.6311 | EN 10028-2 | Plate | EN 13445-2 & EN 13480-2 |
| 15NiCuMoNb5-6-4 15NiCuMoNb5-6-4 | 1.6368 1.6368 | EN 10028-2 EN 10216-2 | Plate Smls. tube | EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 |
| L415QE L415QE | 1.8947 1.8947 | EN ISO 3183 EN 10253-2 | Pipe for natural gas pipeline Fitting | – – |
| L450QE L450QE | 1.8952 1.8952 | EN ISO 3183 EN 10253-2 | Pipe for natural gas pipeline Fitting | – – |
| L485QE L485QE | 1.8955 1.8955 | EN ISO 3183 EN 10253-2 | Pipe for natural gas pipeline Fitting | – – |
| L550QE | 1.8957 | EN ISO 3183 | Pipe for natural gas pipeline | – |
| P460Q | 1.8870 | EN 10028-6 | Plate | EN 13445-2 & EN 13480-2 |
| P460QH | 1.8871 1.8871 | EN 10028-6 EN 10273 | Plate Bar | EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 |
| P460QL1 | 1.8872 | EN 10028-6 | Plate | EN 13445-2 & EN 13480-2 |
| P460QL2 | 1.8864 | EN 10028-6 | Plate | EN 13445-2 & EN 13480-2 |
| P500Q | 1.8873 | EN 10028-6 | Plate | EN 13445-2 & EN 13480-2 |
| P500QH P500QH | 1.8874 1.8874 | EN 10028-6 EN 10273 | Plate Bar | EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 |
| P500QL1 | 1.8875 | EN 10028-6 | Plate | EN 13445-2 & EN 13480-2 |
| P500QL2 | 1.8865 | EN 10028-6 | Plate | EN 13445-2 & EN 13480-2 |
| P620QH | 1.8877 | EN 10216-3 | Smls. tube | EN 13445-2 & EN 13480-2 |
| S690Q | 1.8931 | EN 10025-6 | Plate | MAXIL® 690 |
| P690Q | 1.8879 1.8879 | EN 10028-6 EN 10216-3 | Plate Smls. tube | EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 |
| S690QL | 1.8928 | EN 10025-6 | Plate | MAXIL® 690QL |
| P690QH P690QH P690QH | 1.8880 1.8880 1.8880 | EN 10028-6 EN 10216-3 EN 10273 | Plate Smls. tube Bar | EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 |
| S690QL1 | 1.8988 | EN 10025-6 | Plate | MAXIL® 690QL1 |
| P690QL1 P690QL1 | 1.8881 1.8881 | EN 10028-6 EN 10216-3 | Plate Smls. tube | EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 |
| P690QL2 P690QL2 | 1.8888 1.8888 | EN 10028-6 EN 10216-3 | Plate Smls. tube | EN 13445-2 & EN 13480-2 EN 13445-2 & EN 13480-2 |
| P620Q | 1.8876 | EN 10216-3 | Smls. tube | EN 13445-2 & EN 13480-2 |
| P620QL | 1.8890 | EN 10216-3 | Smls. pipe | EN 13445-2 & EN 13480-2 |
| P420QH | 1.8936 | EN 10224-4 | Forging | EN 13445-2 & EN 13480-2 |
| F F | K11576 K11576 | ASTM A–517 ASTM A-592 | Plate Forging | ASME BPVC ASME BPVC |
| B B | K11630 K11630 | ASTM A–514 ASTM A-517 | Plate Forging | ASME BPVC ASME BPVC |
| E | K11695 | ASTM A–592 | Forging | ASME BPVC |
| A A A | K11856 K11856 K11856 | ASTM A–514 ASTM A-517 ASTM A–592 | Plate Forging Forging | ASME BPVC ASME BPVC ASME BPVC |
| 3, Cl. 1 3, Cl. 2 | K12042 K12042 | ASTM A-508 ASTM A-508 | Forging Forging | ASME BPVC ASME BPVC |
| A, Cl. 1 A, Cl. 2 A, Cl. 3 J100 | K12521 K12521 K12521 K12521 | ASTM A-533 ASTM A-533 ASTM A-533 ASTM A-672 | Plate Plate Plate Fusion welded pipe | ASME BPVC ASME BPVC ASME BPVC ASME BPVC |
| D, Cl. 1 D, Cl. 2 D, Cl. 3 | K12529 K12529 K12529 | ASTM A-533 ASTM A-533 ASTM A-533 | Plate Plate Plate | ASME BPVC ASME BPVC ASME BPVC |
| B, Cl. 1 B, Cl. 2 B, Cl. 3 | K12539 K12539 K12539 | ASTM A-533 ASTM A-533 ASTM A-533 | Plate Plate Plate | ASME BPVC ASME BPVC ASME BPVC |
| C, Cl. 1 C, Cl. 2 C, Cl. 3 C, Cl. 4 | K12554 K12554 K12554 K12554 | ASTM A-533 ASTM A-533 ASTM A-533 ASTM A-533 | Plate Plate Plate Plate | ASME BPVC ASME BPVC ASME BPVC ASME BPVC |
| 2, Cl. 1 2, Cl. 2 | K12766 K12766 | ASTM A-508 ASTM A-508 | Forging Forging | ASME BPVC ASME BPVC |
| E E | K21604 K21604 | ASTM A–514 ASTM A–517 | Plate Plate | ASME BPVC ASME BPVC |
| P P | K21650 K21650 | ASTM A–514 ASTM A–517 | Plate Plate | ASME BPVC ASME BPVC |
| 4N, Cl. 1 4N, Cl. 2 4N, Cl. 3 | K22375 K22375 K22375 | ASTM A-508 ASTM A-508 ASTM A-508 | Forging Forging Forging | ASME BPVC ASME BPVC ASME BPVC |
| B, Cl. 1 B, Cl. 2 B, Cl. 3 | K42339 K42339 K42339 | ASTM A-543 ASTM A-543 ASTM A-543 | Plate Plate Plate | ASME BPVC ASME BPVC ASME BPVC |
| 5, Cl. 1 5, Cl. 2 | K42365 K42365 | ASTM A-508 ASTM A-508 | Forging Forging | ASME BPVC ASME BPVC ASME BPVC |
| Q | – | ASTM A–514 | Plate | ASME BPVC |
| C, Cl. 1 C, Cl. 2 C, Cl. 3 | – – – | ASTM A-543 ASTM A-543 ASTM A-543 | Plate Plate Plate | ASME BPVC ASME BPVC ASME BPVC |
| J80 J90 | – – | ASTM A-672 ASTM A-672 | Fusion welded pipe Fusion welded pipe | ASME BPVC ASME BPVC ASME BPVC |
| 4, Cl. A 4, Cl. B 4, Cl. E | J13047 J13047 J13047 | ASTM A-487 ASTM A-487 ASTM A-487 | Casting Casting Casting | ASME BPVC ASME BPVC ASME BPVC |
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