1350MPa级高强度马氏体钢组织与力学性能的研究

发布时间：2018-05-26 01:32

  本文选题：40CrNi3MoV钢 + 50CrNi5MoV钢　； 参考：《昆明理工大学》2017年硕士论文

【摘要】：40CrNi3MoV钢是一种典型的中碳CrNiMoV钢,经淬火和高温回火后,具有较高的强度和优良的韧塑性,被广泛应用于制造高压容器等大型锻件。随着压力容器承受压力提高和减重的要求,在保证良好的韧塑性前提下,需要将40CrNi3MoV钢的屈服强度水平从目前的l000MPa级提高到1350MPa级。本文在40CrNi3MoV钢的基础上,通过提高C、Ni、Mo元素的含量,研制屈服强度为 1350MPa 级的新型 50CrNi5MoV 钢。并通过 SEM、TEM、EBSD、XRD、Thermo-Calc计算以及相分析等方法,重点研究了回火温度对传统40CrNi3MoV钢和新型50CrNi5MoV钢组织与力学性能的影响。结果表明:1、在40CrNi3MoV钢的基础上,增加C、Ni、Mo的含量得到的50CrNi5MoV钢经淬火和高温回火后的组织明显细化,且碳化物数量增加。550℃回火后50CrNi5MoV钢中的M2C含量是40CrNi3MoV钢的3倍。2、与40CrNi3MoV钢相比,50CrNi5MoV钢中的大角度晶界所占的比例以及残余奥氏体的含量均增加,残余奥氏体在试验钢中呈粒状或块状分布于基体中。3、40CrNi3MoV和50CrNi5MoV试验钢的硬度和强度随回火温度的升高而降低,塑性和冲击吸收能量的变化趋势则相反。将C含量从0.38%提高到0.49%,Mo含量从0.43%提高到1.06%后,由于M2C的二次硬化作用,经500℃至550℃回火后,50CrNi5MoV钢硬度和强度均升高。50CrNi5MoV钢经550℃回火后的屈服强度达到了 1350MPa级,同时具有良好的室温塑韧性和低温韧性;室温AK46J,(-40℃)KV223J,KIcl04MPa·m12。4、试验钢经500℃至650℃不同温度回火后,50CrNi5MoV钢在350℃下的抗拉强度和屈服强度分别比40CrNi3MoV钢高210MPa和140MPa左右。5、试验钢经550℃回火后,在350℃至500℃下的抗拉强度下降率相差不大。不过由于50CrNi5MoV钢室温强度高,其在500℃高温下的抗拉强度仍不低于lOOOMPa,比40CrNi3MoV钢高200MPa左右,说明50CrNi5MoV钢更适合在高温下服役。综上所述,在40CrNi3MoV钢的基础是上,通过提高部分合金元素的含量,成功研发了具有良好韧塑性和高温性能的1350MPa级高强度马氏体钢50CrNi5MoV,为高压容器等大型锻件减重奠定了基础。
[Abstract]:40CrNi3MoV steel is a typical medium carbon CrNiMoV steel. After quenching and tempering at high temperature, 40CrNi3MoV steel has high strength and excellent ductility, so it is widely used in manufacturing large forgings such as high pressure vessels. With the requirement of pressure increase and weight loss in pressure vessel, the yield strength of 40CrNi3MoV steel should be raised from the current l000MPa grade to the 1350MPa grade under the premise of good ductility. On the basis of 40CrNi3MoV steel, a new type of 50CrNi5MoV steel with yield strength of 1350MPa grade was developed by increasing the content of Cni Mo element. The effect of tempering temperature on the microstructure and mechanical properties of traditional 40CrNi3MoV steel and new 50CrNi5MoV steel was studied by means of the calculation and phase analysis of SEMTEMU EBSDX XRDX Thermo-Calc. The results show that on the basis of 40CrNi3MoV steel, the microstructure of 50CrNi5MoV steel obtained by quenching and tempering at high temperature is obviously refined by increasing the content of Cni Mo. After tempering at .550 鈩，

本文编号：1935425