新型油井管钢33Mn2V的奥氏体晶粒长大规律

AUSTENITE GRAIN GROWTH BEHAVIOR OF STEEL 33Mn2V DESIGNED FOR OIL-WELL TUBES

系统研究了用于生产N80级热轧非调质无缝油井管的钢种33Mn2V在不同加热温度和不同保温时间下的奥氏体晶粒长大规律．结果表明，该钢在1100和1200℃保温时，奥氏体晶粒等温长大规律较好地服从抛物线型经验表达式，等温长大指数n均相当接近1／2．若等温时间为10min，利用ASTM晶粒度级别等于5.00的临界判据定义的该钢实用奥氏体晶粒粗化温度位于1250℃左右；在900—1250℃温度范围内，该钢种奥氏体平均晶粒尺寸(D)与加热温度(T)的定量关系近似服从Arrhenius关系：D=1.12×10～4exp(-8.31×10～3／T)．表明该钢在高温加热时具有较好的抗晶粒粗化能力，此结论对于将该钢种实际应用于N80级的热轧非调质无缝油井管工业化生产具有重要参考价值．

For a better understanding of new steel 33Mn2V for oil-well tubes, austenite grain growth behavior of the steel is experimentally studied at various elevated temperatures and holding for different times. Although the steel has no sharp defined grain coarsening temperature from the grain size-temperature curve, a kind of austenite grain coarsening temperature is practically defined as about 1250 degreesC according to ASTM grain size grade G = 5.'00. It is also found that, when heating within the range from 900 degreesC to 1250 degreesC, the temperature dependence of the average austenite grain size (pm) of the steel can be well described by an Arrhenius-type equation: (D) over bar = 1.12 x 10(4) exp(-8.31 x 10(3) /T). Isothermal growth equations of austenite grains in parabolic type with the exponent close to 1/2 are also obtained when the steel was heated at 1100 degreesC and 1200 degreesC, respectively. The results show that the steel has good anti-coarsening ability at elevated temperatures, which is very important in putting the said steel into industrial production of N80 grade hot-rolling non-quenched/tempered seamless oil-well tubes.