Construcción de curvas límite de formabilidad para aceros de bajo carbono utilizados en la manufactura de cilindros a presión

Context: The aim of this study is to determine the formability of SG295 (2,2 mm thick) and SG325 (2,3 mm thick) steel sheets, as well as their relationship with the sheets’ behavior in deep drawing and stretching operations. To this effect, chemical, metallographic, and mechanical analyses of the sheets were carried out. Method: The chemical analysis was carried out via optical emission spectrometry, and the metallographic structure was analyzed using the ASTM E3 standard. The intrinsic properties related to the formability of materials such as the elongation to fracture for a 50 mm gauge length, the conventional yield limit at 0,2% elongation, the ultimate strength, the strain hardening exponent, and the anisotropy coefficient at 15% elongation were determined through tensile tests according to ASTM E8M, ASTM E646, and ASTM 517. Forming limit curves were determined under ASTM E2218, for which a device was designed, built, and attached to a universal testing machine. Results: The results for the SG295 and SG325 steel sheets were as follows: tensile strength; 450 and 520 MPa; elongation at fracture: 24,9 and 17,2%; strain hardening exponent: 0,24 and 0,19; normal anisotropy: 1,64 and 1,29; planar anisotropy: 0,23 and -0,02. The FLD0 determined from the formality limit curves (FLCs) for the two steel sheets showed ε1 values of 0,281 and 0,336, respectively. Conclusions: Although the intrinsic properties (such as A50, n, and rm) of the SG295 steel sheet show values related to a greater formability, the FLCs show that SG325 steel performs slightly better due to its greater thickness.Contexto: El objetivo de este trabajo fue determinar la formabilidad de láminas de acero SG295 (2,2 mm de grosor) y SG325 (2,3 mm de grosor), así como su relación con el comportamiento de estas frente a operaciones de estirado y embutido profundo. Para tal fin, se realizaron análisis químicos, metalográficos y mecánicos en las láminas. Método: El análisis químico se realizó mediante espectrometría de emisión óptica, y la estructura metalográfica se analizó utilizando el estándar ASTM E3. Las propiedades intrínsecas relacionadas con la formabilidad de los materiales, tales como el alargamiento a la fractura para una longitud de referencia de 50 mm, el límite de rendimiento convencional al 0,2 % de elongación, la resistencia última, el exponente de endurecimiento por deformación y el coeficiente de anisotropía al 15 % de elongación se determinaron mediante pruebas de tracción de acuerdo con ASTM E8M, ASTM E646 y ASTM 517. Las curvas límite de formabilidad se determinaron bajo la norma ASTM E2218, para lo cual se diseñó, construyó y acopló un dispositivo a una máquina universal de ensayos. Resultados: Los resultados para las láminas de acero SG295 y SG325 fueron los siguientes: resistencia a la tracción: 450 y 520 MPa; elongación hasta fractura: de 24,9 y 17,2 %; exponente de endurecimiento por deformación: 0,24 y 0,19; anisotropía normal: 1,64 y 1,29; anisotropía planar: 0,23 y -0,02. Los FLD0 determinados a partir de las curvas límite de formalidad (CLF) para las dos láminas de acero mostraron valores para ε1 de 0,281 y 0,336 respectivamente. Conclusiones: Aunque las propiedades intrínsecas (como A50, n y rm) de la lámina de acero SG295 presentan valores relacionados con una mayor formabilidad, las CLF muestran que el acero SG325 se desempeña ligeramente mejor debido a su mayor espesor

Construction of Formability Limit Curves for Low-Carbon Steels Used in the Manufacture of Pressure Cylinders

Context: The aim of this study is to determine the formability of SG295 (2,2 mm thick) and SG325 (2,3 mm thick) steel sheets, as well as their relationship with the sheets’ behavior in deep drawing and stretching operations. To this effect, chemical, metallographic, and mechanical analyses of the sheets were carried out. Method: The chemical analysis was carried out via optical emission spectrometry, and the metallographic structure was analyzed using the ASTM E3 standard. The intrinsic properties related to the formability of materials such as the elongation to fracture for a 50 mm gauge length, the conventional yield limit at 0,2% elongation, the ultimate strength, the strain hardening exponent, and the anisotropy coefficient at 15% elongation were determined through tensile tests according to ASTM E8M, ASTM E646, and ASTM 517. Forming limit curves were determined under ASTM E2218, for which a device was designed, built, and attached to a universal testing machine. Results: The results for the SG295 and SG325 steel sheets were as follows: tensile strength; 450 and 520 MPa; elongation at fracture: 24,9 and 17,2%; strain hardening exponent: 0,24 and 0,19; normal anisotropy: 1,64 and 1,29; planar anisotropy: 0,23 and -0,02. The FLD0 determined from the formality limit curves (FLCs) for the two steel sheets showed ε1 values of 0,281 and 0,336, respectively. Conclusions: Although the intrinsic properties (such as A50, n, and rm) of the SG295 steel sheet show values related to a greater formability, the FLCs show that SG325 steel performs slightly better due to its greater thickness