S32750超级双相不锈钢管坯的热塑性研究

Study on Thermoplasticity of S32750 Super Duplex Stainless Steel Round Billet for Pipe-making

二辐斜轧热轧穿孔机制造双相不锈钢毛管具有成本低的优点,但由于穿孔机变形剧烈,对管坯材料热塑性要求很高。针对S32750超级双相不锈钢管坯,釆用Gleeble1500热模拟试验机进行高温拉伸试验,得到不同温度下材料断面收缩率和抗拉强度的变化规律,并用扫描电镜分析其断口形貌,测量不同温度下材料中铁素体的含量,与热力学软件计算出的铁素体理论值进行比较,发现在高温下S32750管坯铁素体含量控制在60%~70%时,材料的热塑性最为理想,为该材料管坯顺利实现热穿孔提供了依据。

Although the 2-roll rotary hot-piercing mill has the advantage of cost effectiveness when making the duplex stainless steel shell, due to its severe deformation during the operation, very high thermoplasticity of the round billet is required. Addressing the S32750 super duplex stainless steel round billet, the Gleeble 1500 thermal simulator is used to carry out the high-temperature tensile test, having got the reduction of the cross-sectional area and the change law of the tensile strength of the steel at different temperatures. The fracture morphology is analyzed with the SEM, and the ferrite contents of the steel at different temperatures are also measured, and then compared with the theoretical values of the ferrite contents as calculated by relevant thermodynamic software. As a result, it is identified that when the ferrite content of the S32750 steel billet is controlled within the range of 60%-70% at a high temperature, it presents the best thermoplasticity, which provides a basis for smooth hot-piercing of the said billet.