合金元素对双相钢性能影响及其热加工性能研究

Effect of alloy element on the properties of double phase steel and its hot-working character

具有铁素体加回火马氏体两相组织的高铬合金强度高、韧性好,同时抗腐蚀性能优良,在油气开采领域具有广阔的应用前景。研究N、Cu、Mo、Nb、Ni、Cr元素含量对合金组织组成、力学性能影响,结果显示,降低N和Cu元素含量将使双相钢中铁素体比例提高,导致两相界面增大,使材料低温冲击韧性降低。Mo含量下降将使材料强度降低,少量Nb元素的添加对合金强度提高作用不明显。提高合金中Ni、N、Cr、Mo元素含量将使奥氏体保持到室温下,材料组织转变为铁素体加奥氏体两相组织,材料屈服强度低于500 MPa。高温应力—应变曲线检测结果显示,双相合金在1 100~1 200℃范围内变形抗力较小,但轧制过程中易在铁素体、奥氏体两相界面处产生裂纹。

Double phase steel with ferrite and tempered martensite structure shows high strength,good toughness and corrosion resistant. It has wide potential application in the area of hydrocarbon recovery. Effect of N,Cu,Mo,Nb,Ni,Cr element content on the alloy properties and structure was studied. It was found that the ferrite fraction of the alloy decreased as the N or Cu content increasing.The increase of phase contact area leaded to the decrease of material low-temperature toughness. Mo content decrease will result in the strength reduction. Microalloy strengthening effect of Nb is not obvious in these alloys. The Ni,N,Cr or Mo content increase will induce the alloy phase structure change,from ferrite and martensite to ferrite and austenite two phase structure,and the yield strength will drop to lower than 500 MPa. Through the high-temperature stress-strain curves measuring,it was found that this alloy has better hot-working properties in 1 100 to 1 200 ℃ temperature scale,but the crack was easy to form in the ferrite and martensite interface during hot rolling.