What ASTM A515 Grade 70 Is
ASTM A515 Grade 70 is a carbon-silicon steel plate specification for boilers and pressure vessels that serve at intermediate and higher temperatures. The number 70 in the grade stands for a minimum tensile strength of 70 ksi, roughly 485 MPa, and the material is normally supplied in the normalized condition so that the ferrite-pearlite structure stays stable during long, hot service.
Plates are produced to ASTM A515/A515M and to the matching ASME SA515 specification; for pressure boundary work the two documents are technically equivalent. The acceptance envelope that any equivalent grade has to meet includes a minimum yield strength of 260 MPa, a tensile range of 485-620 MPa, and a minimum elongation of 21 percent in a 50 mm gauge length or 17 percent in a 200 mm gauge length.
Equivalent Grades of ASTM A515 Grade 70
A515 Grade 70 has been specified on international projects for decades, so almost every national boiler-plate system contains a comparable grade. The table below collects the cross-references used most often when an A515 Grade 70 plate has to be sourced or substituted.
| Region | System | Equivalent grade |
|---|---|---|
| Europe | KG / KW / KT boiler plate series | KG, KW, KT |
| Germany | DIN 17155 | WStE 315 |
| France | A48 | CP, AP, FP |
| Italy | Fe 460-2-KW | Fe 460-2-KW |
| Sweden | SS 21 02 01 | SS 21 02 01 |
| United Kingdom | Gr 360 / Gr 400 | Gr 360, Gr 400 |
| Japan | JIS G3103 | SB480 |
| United States | ASTM A414 | Grade F |
JIS G3103 SB480 and ASTM A414 Grade F sit closest to the tensile level of A515 Grade 70, while the European KG, KW and KT family and the French A48 CP, AP and FP grades are chosen when a normalized carbon-silicon plate for elevated temperature is needed. Substitution should always be checked against the design code, because impact requirements and allowable stress values are set by the code rather than by the grade name alone.
Chemical Composition and Mechanical Properties
The chemistry of A515 Grade 70 is deliberately simple: carbon and manganese supply strength, silicon supports behaviour at elevated temperature, and phosphorus and sulphur are restricted to protect toughness and weldability. Carbon is tiered by thickness so that heavier plate can still be fully normalized.
| Thickness T (mm) | C max (%) | Si (%) | Mn (%) | P max (%) | S max (%) |
|---|---|---|---|---|---|
| T up to 25 | 0.24 | 0.13-0.45 | 0.98 | 0.025 | 0.025 |
| 25 < T up to 50 | 0.27 | 0.13-0.45 | 0.98 | 0.025 | 0.025 |
| 50 < T up to 100 | 0.29 | 0.13-0.45 | 0.98 | 0.025 | 0.025 |
| T above 100 | 0.31 | 0.13-0.45 | 0.98 | 0.025 | 0.025 |
| Property | Value |
|---|---|
| Minimum yield strength | 260 MPa |
| Tensile strength | 485-620 MPa |
| Minimum elongation, 50 mm gauge | 21 % |
| Minimum elongation, 200 mm gauge | 17 % |
| Condition as supplied | Normalized |
A515 Grade 60, 65 and 70, and the Difference from A516
ASTM A515 is published in three strength levels. All three are normalized carbon-silicon boiler steels and differ mainly in tensile strength and carbon content:
A515 Grade 60 - minimum tensile strength 415 MPa
A515 Grade 65 - minimum tensile strength 450 MPa
A515 Grade 70 - minimum tensile strength 485 MPa, with the highest carbon level of the three
A515 and A516 look alike on a mill certificate but serve different temperature windows. A515 plate is a carbon-silicon product for intermediate and higher temperature service, while A516 plate is a carbon steel with better notch toughness for moderate and lower temperature service. The thickness limits differ as well: ASME SA-515 Grade 70 is normally used up to about 50 mm, whereas SA-516 Grade 70 is available up to 204 mm. Below the transition temperature A516 retains more impact energy; above it A515 is the more suitable choice.
Plate Sizes, Heat Treatment and Applications
Thickness range: 6 mm to 300 mm
Width range: 1500 mm to 4050 mm
Length range: 3000 mm to 15000 mm
Heat treatment: normalized, by normalizing rolling or furnace normalizing
Forms: plain plate, cut-to-size plate, circle, ring and profiled blank
Surface options: hot rolled, shot blasted, shop primer coated, edge machined
A515 Grade 70 plate is fabricated into boiler shells, drums and headers, heat exchanger components, condensers, chemical process vessels, gas processing equipment and power plant pressure parts. It welds with conventional carbon steel procedures provided a controlled carbon equivalent is maintained, heavier sections are preheated, and post-weld heat treatment is applied where the service demands it. Plates for sour service can be supplied with NACE MR0175 and HIC testing, and ultrasonic testing is available for critical pressure boundaries.
Frequently Asked Questions
Q: What is A515 Grade 70 material?
A: A515 Grade 70 is a normalized carbon-silicon steel plate specified by ASTM and ASME for boilers and pressure vessels in intermediate and higher temperature service. It combines a minimum yield strength of 260 MPa with a tensile range of 485-620 MPa, which corresponds to the 70 ksi strength class in its name.
Q: What is the equivalent of ASTM A515 Grade 70?
A: The commonly used equivalents are JIS G3103 SB480, DIN 17155 WStE 315, French A48 CP, AP and FP, Italian Fe 460-2-KW, Swedish SS 21 02 01, UK Gr 360 and Gr 400, and ASTM A414 Grade F.
Q: What is the chemical composition of ASTM A515 Grade 70?
A: Carbon is limited to 0.24 percent up to 25 mm and rises in steps to 0.31 percent above 100 mm. Silicon is held between 0.13 and 0.45 percent, manganese to 0.98 percent, and phosphorus and sulphur are each limited to 0.025 percent maximum.
Q: What is the difference between ASTM A515 Grade 70 and ASTM A516 Grade 70?
A: A515 Grade 70 is designed for intermediate and higher temperature service and is supplied normalized, while A516 Grade 70 is optimized for moderate and lower temperature service and offers better notch toughness in cold conditions.
Q: What is the difference between SA515 Grade 70 and SA516 Grade 70?
A: Both are ASME pressure vessel plate specifications. SA-515 Grade 70 is a carbon-silicon steel for intermediate or higher temperature service with a normal maximum thickness of about 50 mm, while SA-516 Grade 70 is used up to 204 mm because of its lower carbon content and improved toughness.
Q: Are A515 Grade 70 plates suitable for welding?
A: Yes. The grade has good weldability when a controlled carbon equivalent is maintained. Heavier sections benefit from preheating, and post-weld heat treatment is applied where the design code or the service temperature requires it.
Q: What sizes of A515 Grade 70 plate are available?
A: Plates are supplied from 6 mm to 300 mm thick, 1500 mm to 4050 mm wide and 3000 mm to 15000 mm long, with cut-to-size plate, circles, rings and profiled blanks available to drawing.
Q: Does ASTM A515 Grade 70 meet NACE MR0175 requirements?
A: Plates for sour service can be supplied with NACE MR0175 and HIC testing, so the delivered material satisfies the hardness and cracking-resistance requirements of the specification.
