控轧和时效对570 MPa超低碳贝氏体钢组织和性能的影响

成分(%)为0.02C-1.55Mn-0.62Ni-0.53Cu-0.003 5 B-0.055V-0.019Ti-0.028Nb的超低碳贝氏体钢ULCB570,由试验室50 kg真空感应炉冶炼,锻80 mm厚板坯,经开轧温度1 150℃,终轧温度900℃空冷轧成25mm厚板材,并用Thermecmaster-Z热模拟试验机测试了该钢的形变奥氏体连续冷却转变曲线。结果表明,该钢形变后在0.130℃/s冷却下的组织为贝氏体-铁素体+第2相或析出物,轧态抗张强度σ_b为595 MPa,冲击韧性A_KV为180 J,轧态+600℃时效时的σ_b增加至610 MPa,A_KV增加至202 J,达到570 MPa级钢板的性能要求。

Effect of Control Rolling and Aging on Structure and Properties of 570 MPa Ultra Low Carbon Bainitic Steel

The ulra low carbon bainitic steel ULCB570(0.02C- 1.55Mn-0.62Ni-0.53Cu-0.0035B-0.055V-0.019Ti-  0.028Nb was melted by a 50 kg vacuum induction furnace in laboratory,of which the 25 mm finished plate was rolled from forged 80 mm slab with beginning rolling temperature 1150 ℃,finishing temperature 900 ℃ and air cooling. The continuous cooling transformation curves of deforming austenite was measured by a Thermecmaster-Z thermal simulation machine.  The results showed that the structure of steel deformed with cooling rate 0. 1~30 ℃/s was bainite-ferrite + secondary phase (precipitates);the tensile strength on of steel as rolled condition was 595 MPa,impact toughness A_KV 180 J,of which as rolled + 600 ℃ aged condition the tensile strength σ_b of steel increased to 610 MPa, impact toughness A_KV to 202 J to meet the requirement for properties of 570 MPa steel plate.