Direct Answer: ASTM A148 / A148M is the standard specification for high-strength carbon and alloy steel castings for structural purposes where required tensile strength exceeds ASTM A27 limits. Grades are designated by minimum tensile and yield strength in ksi (or MPa)—most commonly Grade 80-50 (550-345), Grade 90-60 (620-415), Grade 105-85 (725-585), and Grade 120-95 (825-655)— leaving exact alloy chemistry (such as Cr-Mo 4140 or Ni-Cr-Mo 8630 / 4340) to the foundry’s metallurgical design to achieve target through-thickness hardenability.
Direct Foundry & CNC Manufacturing — Pingdu, Qingdao
Qingdao Yucheng Machine (YCUMETAL) operates a 34,000 m² integrated casting and CNC machining facility in Pingdu, Qingdao (approx. 50 km from Qingdao Port). We pour and finish-machine stainless steel, carbon & alloy steel, ductile/grey iron, aluminum, and copper/bronze alloys across silica-sol investment casting, sand casting, lost foam, gravity, and low-pressure casting.
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1. ASTM A148 Mechanical Property Table & Recommended Alloy Systems
Because ASTM A148 only caps sulfur (≤ 0.06%) and phosphorus (≤ 0.05%) in the base standard, the foundry must select the right low-alloy steel chemistry and quench-and-temper (Q&T) cycle based on your casting’s ruling section thickness:
| ASTM A148 Grade (ksi [MPa]) | Min Tensile Strength | Min Yield Strength | Min Elongation / Reduction of Area | YCUMETAL Melt Chemistry & Heat Treatment | Typical Heavy-Duty Applications |
|---|---|---|---|---|---|
| 80-40 [550-275] 80-50 [550-345] |
80 ksi (550 MPa) | 40 ksi (275 MPa) 50 ksi (345 MPa) |
18% / 30% 22% / 35% |
C-Mn-Si or Mn-Mo (ZG310-570 / 1040 mod); Normalized & Tempered or Q&T (~163–207 HB) | Trailer hitches, crane sheaves, heavy construction brackets, rail couplers |
| 90-60 [620-415] | 90 ksi (620 MPa) | 60 ksi (415 MPa) | 20% / 40% | Cr-Mo (4130 / ZG30CrMo) or Ni-Cr-Mo (8630); Quenched & Tempered (~187–229 HB) | Excavator linkage arms, winch drums, mining track shoes, oilfield elevators |
| 105-85 [725-585] | 105 ksi (725 MPa) | 85 ksi (585 MPa) | 17% / 35% | Cr-Mo (4140 / ZG42CrMo) or Ni-Cr-Mo (8630/4330); Oil/Polymer Quench + Temper (~217–269 HB) | High-torque gear blanks, hydraulic cylinder clevises, rock-drilling chucks |
| 120-95 [825-655] 150-135 [1035-930] |
120 ksi (825 MPa) 150 ksi (1,035 MPa) |
95 ksi (655 MPa) 135 ksi (930 MPa) |
14% / 30% 7% / 18% |
Ni-Cr-Mo (Cast 4330 / 4340 / ZG35CrNiMo); Homogenize + Austenitize + Quench + Double Temper (260–340 HB) | Ripper shanks, crusher toggle seats, high-load automotive & defense structural nodes |
2. How to Avoid Quench Cracking & Core Softness in ASTM A148 Castings
A common failure when sourcing ASTM A148 90-60 or 105-85 castings from general foundries is using plain carbon steel with severe water quenching—which causes quench cracks at section transitions while leaving thick bosses soft in the core. At YCUMETAL’s 34,000 m² Pingdu plant, we control P and S well below 0.025% (vs ASTM’s 0.05–0.06% limit), match Cr-Mo or Ni-Cr-Mo hardenability to wall thickness, perform homogenizing normalize prior to oil/polymer quench and temper, and verify every heat with EN 10204 3.1 MTR tensile, Brinell hardness, and magnetic particle (MT) / industrial CT inspection. Send your structural casting drawing for a 24-hour DFM and alloy recommendation.
Frequently Asked Questions (Engineering FAQ)
What is the difference between ASTM A27 and ASTM A148 steel castings?
ASTM A27 covers mild-to-medium strength carbon steel castings up to 70 ksi (485 MPa) tensile strength (such as Grade 65-35 and 70-40) for general weldable applications. ASTM A148 covers high-strength structural carbon and alloy steel castings starting at 80 ksi (550 MPa) up to 260 ksi (1,795 MPa) tensile strength, typically requiring alloy additions (Cr, Mo, Ni) and quench-and-temper heat treatment.
Can ASTM A148 Grade 90-60 or 105-85 castings be welded in the field?
Because ASTM A148 90-60 and 105-85 rely on Cr-Mo or Ni-Cr-Mo chemistries with higher carbon equivalents (CE > 0.55), welding requires low-hydrogen electrodes, controlled preheating (175–260 °C), and mandatory post-weld stress relief or re-tempering below the original tempering temperature to prevent heat-affected zone (HAZ) cold cracking.
Should ASTM A148 castings be CNC machined before or after quench and temper?
For Grades 80-50, 90-60, and 105-85 (163 to 269 HB), YCUMETAL performs final CNC turning, milling, and boring AFTER quench-and-temper heat treatment so that thermal distortion cannot affect IT6–IT7 bearing bores or mounting datums.
For production DFM, tooling, and batch inspection on these components, explore our casting heat treatment and surface finishing capabilities at YCUMETAL’s 34,000㎡ Pingdu facility.
For production DFM, tooling, and batch inspection on these components, explore our agricultural machinery castings capabilities at YCUMETAL’s 34,000㎡ Pingdu facility.
For DFM review, tooling, and batch inspection on these components, explore our electronics and telecom enclosure castings capabilities at YCUMETAL’s 34,000㎡ Pingdu facility.
For production DFM review, tooling, and batch inspection on these components, explore our aerospace precision investment castings capabilities at YCUMETAL’s 34,000㎡ Pingdu facility.
Related Casting & CNC Engineering Guides (Carbon Steel, Low-Alloy Steel & International Material Cross-Reference (WCB / LCB / WCC / WC6 / Cr-Mo))
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Frequently Asked Engineering Questions
What is the difference between ASTM A27 and ASTM A148 steel castings?
ASTM A27 covers mild-to-medium strength carbon steel castings up to 70 ksi (485 MPa) tensile strength (such as Grade 65-35 and 70-40) for general weldable applications. ASTM A148 covers high-strength structural carbon and alloy steel castings starting at 80 ksi (550 MPa) up to 260 ksi (1,795 MPa) tensile strength, typically requiring alloy additions (Cr, Mo, Ni) and quench-and-temper heat treatment.
Can ASTM A148 Grade 90-60 or 105-85 castings be welded in the field?
Because ASTM A148 90-60 and 105-85 rely on Cr-Mo or Ni-Cr-Mo chemistries with higher carbon equivalents (CE > 0.55), welding requires low-hydrogen electrodes, controlled preheating (175–260 °C), and mandatory post-weld stress relief or re-tempering below the original tempering temperature to prevent heat-affected zone (HAZ) cold cracking.
Should ASTM A148 castings be CNC machined before or after quench and temper?
For Grades 80-50, 90-60, and 105-85 (163 to 269 HB), YCUMETAL performs final CNC turning, milling, and boring AFTER quench-and-temper heat treatment so that thermal distortion cannot affect IT6–IT7 bearing bores or mounting datums.
Complete Foundry & CNC Engineering Technical Index (Section 3 of 3)
Browse our Latest Engineering News, Casting Alloy & Materials Directory, Foundry & CNC Blog, ASTM A148 Structural Steel Castings, ASTM A743 vs A351 Stainless Castings, Foundry Overview, and RFQ Confirmation Portal, plus industry solutions for Commercial Hardware, Aerospace, Industrial Automation, Medical Devices, and Construction Machinery:
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