回火温度对热轧态高强度贝氏体钢管组织性能的影响

热轧态高强度新型贝氏体钢管具有较高强度,但冲击值较低,回火可以改善其冲击韧性。研究回火温度对热轧态高强度新型贝氏体钢管组织和性能的影响。试验结果表明:550℃以下温度回火,随回火温度提高,该新型贝氏体钢管的抗拉强度有降低趋势,但下降幅度不大;350℃以下温度回火,其冲击值随回火温度的提高而增加;400℃回火时冲击值降低,出现回火脆性;450℃以上温度回火时冲击值增加;250~350℃回火时钢管强度较高,550~650℃回火时韧性较高。400℃以下温度回火,该新型贝氏体钢管的组织均为板条贝氏体、粒状贝氏体、铁素体及残余奥氏体组织;回火温度超过500℃,残余奥氏体完全分解,组织为铁素体和粒状贝氏体。

Effect by Tempering Temperature on Microstructure and Properties of Hot-rolled High Strength Bainite Steel Pipe

The new type hot-rolled hi-strength bainite steel tube possesses rather high strength, but low impact value. However its impact toughness can be improved by the tempering process. The effect by the tempering temperature on the microstructure and properties of the said tube is studied. The test results indicate that with the tempering temperature below 550 ℃,along with increase of the temperature,the tube’s tensile strength trends to be reduced,but not so obviously;and with tempering temperature below 350 ℃,along with the increase of the temperature,the tube’s impact value goes up;while tempered at 400 ℃,the tube’s impact value gets decreased,resulting in tempering-caused brittleness;tempered at more than 450 ℃,the impact value of the tube gets increased;tempered at 250~350 ℃,the tube has higher strength;tempered at 550~650 ℃,the tube presents rather high toughness;and tempered at a temperature below 400 ℃,the new type bainite tube has all bainite microstructures,i.e.,lath bainite,granular bainite,ferrite and residual austenite structures;when the tempering temperature is higher than 500 ℃,the residual austenite structure gets completely resolved,and the structure is of ferrite and granular bainite.