Position of A517 Grade E in the Standard System
A517 Grade E is one of the high strength quenched and tempered alloy steel plate grades issued under ASTM A517/A517M, the specification covering high strength steel plates intended for welded pressure vessels. The grade is a low-alloy, boron-bearing or nickel-chromium-molybdenum type depending on the producer's approved composition, and it is used where ordinary carbon-manganese vessel steel cannot deliver the required strength at the required thickness.
The upper thickness limit for A517 Grade E plate is 150 mm, which places it among the thickest heat-treated pressure vessel grades available. Because the strength is achieved by heat treatment, the specification fixes the thermal cycle that the plate must receive, and the mechanical properties are verified on a specimen taken from the heat treated plate.
Delivery Condition and Mandatory Heat Treatment
A517 plate is delivered in the heat treated condition. The heat treatment route specified for the grade is the same across the grade family: the plate is heated to not less than 900 C, quenched in water or oil, and then tempered at not less than 620 C. The high austenitising temperature dissolves the alloying elements, the quench produces a hard martensitic or bainitic structure, and the tempering treatment restores toughness while retaining the required strength.
The steel is fully killed and must conform to the fine austenitic grain size requirements of ASTM A20/A20M, the general requirements specification covering steel plates for pressure vessels. Fine grain practice is essential because it improves both toughness and resistance to brittle fracture in thick sections.
Chemistry and Mechanical Requirements
| Property | Requirement for Grade E |
|---|---|
| Minimum yield strength | 690 MPa |
| Tensile strength | 795-930 MPa |
| Minimum elongation in 50 mm | 16 percent |
| Maximum thickness | 150 mm |
| Austenitising temperature | Not less than 900 C |
| Tempering temperature | Not less than 620 C |
| Grain size | Fine austenitic grain size to ASTM A20/A20M |
Depending on the producer's approved composition and plate thickness, supplementary requirements such as additional impact testing, restricted chemical analysis, ultrasonic examination or hardness limits can be added to the order.
Where A517 Grade E Plate Is Used
High strength pressure vessel shells and heads
Shipbuilding structures and offshore platform components
Penstock and arc plate for hydropower installations
Drilling rigs and derrick structures
Electric shovels, draglines and mining excavator bodies
Electric wheel dump trucks and mining automobiles
Loader, bulldozer and crane structural parts
Hydraulic supports and heavy coal mining machinery components
Fabrication and Welding Notes
Welding of A517 Grade E requires procedures qualified for the actual strength level and thickness. Low-hydrogen consumables matched to the 690 MPa yield class are used, with controlled preheat, interpass temperature limits and, for thick joints, a controlled heat input range. Post-weld heat treatment must be carried out below the tempering temperature of the base plate so that the delivered strength is preserved; where the design code does not mandate post-weld heat treatment, the fabricator still needs to control hydrogen to avoid delayed cracking.
Flame cutting and thermal forming operations are followed by a review of the local heat history, and cold forming needs adequate bend radius to avoid surface cracking in this high strength plate. Cutting edges are ground smooth before welding and all temporary attachments are removed and dressed.
Quality Control and Delivery Documentation
Each plate is supplied with a test certificate giving the heat number, the actual chemical analysis, the tensile test results, the heat treatment record and, when ordered, the impact and hardness results. Ultrasonic testing can be specified to detect internal discontinuities before fabrication, and dimensional inspection covers thickness, flatness, length, width and edge condition.
Frequently Asked Questions
Q: What is the maximum thickness of A517 Grade E plate?
A: The grade is specified up to 150 mm.
Q: How is A517 Grade E delivered?
A: In the quenched and tempered condition, after austenitising at not less than 900 C, quenching in water or oil and tempering at not less than 620 C.
Q: What is the minimum yield strength of A517 Grade E?
A: 690 MPa, with a tensile strength range of 795 MPa to 930 MPa.
Q: Why is fine austenitic grain size required?
A: Fine grain size improves toughness and reduces the risk of brittle fracture in thick, high strength plate, and ASTM A20/A20M sets the grain size requirements for the grade.
Q: Can A517 Grade E be used for offshore structures?
A: Yes. The combination of high strength and toughness makes it suitable for offshore platform components, shipbuilding structures and penstock plate, provided the welding procedure is qualified for the grade.
Q: Is impact testing included as standard?
A: Impact testing and other additional requirements are ordered as supplementary requirements; the test temperature and minimum absorbed energy are stated in the purchase order.
