设计了碳-硅-锰-铬-钼-铌合金钢,开发出了以粒状贝氏体组织为主的高强度低碳微合金CT80钢级热轧卷板,通过ERW制管和热处理技术,研制出了 31.75 mm×3.175 mm的CT80钢级连续油管,对其组织与力学性能进行了分析.结果表明:管体组织以多边形铁素体为主,辅以针状铁素体、细小的珠光体和M-A岛;管体纵向屈服强度583 MPa,抗拉强度703 MPa,伸长率29.3%;管体内压为34.47 MPa时疲劳寿命达到了634次;管体及焊缝具有良好的的抗HIC和SSCC性能;该连续油管性能指标达到了API 5C7和API 5ST标准要求.

The C-Si-Mn-Cr-Mo-Nb alloy steel was designed.The high strength low carbon microalloy CT80 grade hot rolled coil,whose main microstructure was granular bainite,was developed.Using electric resistance weld(ERW) pipe-making and heat treatment technology,the CT80 grade coiled tubing with specification of  31.75 mm×3175 mm was developed.The microstructure and mechanical properties of the tubing were analyzed.The results indicate that the microstructure of the pipe body was mainly composed of polygonal ferrite with little acicular ferrite,fine pearlite and M-A islands.The yield strength in the longitudinal direction was 583 MPa,the tensile strength was 703 MPa and the elongation was 29.3%.The fatigue life reached 634 cycles when the internal pressure of the pipe body was 34.47 MPa.Both the pipe body and weld had good HIC and SSCC resistance performance.The performance data of the coiled tubing fully conformed to the requirements of API 5C7 and API 5ST specification.