In API 5CT, 4140 L80 corresponds to the 80K yield strength grade defined in the API standard, which is 4140 80K.
4140 L80 steel, through quenching and tempering, achieves a balance between strength and toughness, making it a preferred material for pipes and high-pressure equipment in the oil and gas industry.The following table lists the minimum mechanical property requirement from the API standard.
| Yield strength | Tensile strength | Elongation | Reduction in Area | Hardness | Charpy V,20℃ |
| ≥552 MPa | ≥655MPa | ≥18% | ≥35% | 18-22HRC | ≥27J |