合金元素Ni/Al对45Si2MnCr2Mo超高强韧钢冲击磨料磨损行为的影响

针对不同Ni/Al含量的强塑韧性良好的45Si2MnCr2Mo超高强韧钢,利用MLD-10冲击磨料磨损实验机对其进行了三体磨料磨损实验,系统研究了不同Ni/Al含量对超高强韧钢的磨损失重、硬化层深度以及磨损后表层及亚表层微观形貌的影响,并探讨了磨损机理。结果表明:Ni含量为3%时超高强韧钢的耐磨性最好,磨损百分比最低,为0.391%。当加入0.5%的Al后超高强韧钢的耐磨性降低了1.48,磨损百分比增加到0.42%。添加Ni元素能提高超高强韧钢的磨损性能,但当Al和Ni同时添加时反而不利于改善磨损性能。质量失重是由磨料的嵌入及剥落共同体现的。实验钢经冲击磨料磨损实验后表面和次表面区域通过加工硬化得到强化,Ni含量为3%时超高强韧钢拥有最佳的综合磨损后表面硬度、硬化百分比和有效硬化层深度,磨损过程更均匀。超高强韧钢的磨损形式主要为犁沟、剥落、裂纹、嵌入磨粒、犁沟浪花和挤压堆积。

调质工艺对Cr⁃Ni⁃Mo⁃V超高强韧钢组织和力学性能的影响

利用扫描电镜、金相显微镜、冲击试验机结合维氏硬度计研究了780、830和880℃淬火+500~580℃高温回火处理对Cr⁃Ni⁃Mo⁃V超高强韧钢显微组织和力学性能的影响。结果表明,随回火温度的升高,尺寸较大碳化物会发生溶解转变,合金碳化物由基体中不断弥散析出。硬度和冲击性能均随回火温度升高呈现先增大后降低的趋势,与碳化物弥散析出形貌和残留奥氏体分解转变有关;3种温度淬火试验钢均在540℃回火时出现二次硬化峰值,最高值分别为488、517、532 HV20,在540~560℃回火出现最大冲击吸收能量,分别为49.7、58.5、51.0 J。为充分保证钢的强韧性,最佳热处理工艺为830℃亚温临界淬火+560℃回火。

强烈淬火工艺制备超高强韧钢的应用展望

强烈淬火工艺具有能耗低、无污染及对材料的“超强化”作用等特点,近年来受到国外学者的广泛关注。介绍了强烈淬火工艺国内外发展的现况,亟待建立强烈淬火工艺参数数据库;由于强烈淬火工艺处理后的微观组织性能特点与特种装备用超高强韧钢的性能要求非常契合,提出了将强烈淬火工艺应用于超高强韧钢开发的展望。

激光制备预压应力超高强韧马氏体层的组织与性能

针对飞机、高铁等关键承力构件大载荷重量比的需要,采用激光制备具有超高强韧马氏体成型层,改善关键承力件的力学性能以及表面应力分布。通过显微硬度计、SEM等手段分析激光成型层显微硬度、拉伸性能及断口形貌等,并研究其残余应力。实验表明:原始态试样残余压应力达到300~500 MPa,抗拉强度达1715±35 MPa,延伸率10%±1%;300℃×2hAC试样的抗拉强度1615±35 MPa,延伸率15%±1%;500℃×2hAC试样抗拉强度1565±35 MPa,延伸率13%±1%。当热处理温度大于700℃时,马氏体明显分解,熔覆试样力学性能明显下降。在300M钢表面采用激光成型制备的超高强韧马氏体成型层表面平整无裂纹且致密,具有超高强度、高韧性、高硬度。

Austenite/martensite structure and corresponding ultrahigh strength and high ductility of steels processed by Q&P techniques

The microstructure of steels treated by Q&P(quenching and partitioning) process was characterized,a method of controlling retained austenite fraction based on inhomogeneous martensitic transformation was proposed,and the mechanical properties of steels treated by Q&P process were measured.The results show that the microstructure of the studied steels is mainly composed of initial martensite,fresh martensite and retained austenite.The initial marteniste formed at the first quenching step is easily etched;the fresh martensite formed at the final quenching step looks like 'blocky' type phase,and the retained austenite is mainly located on the packet boundary and initial austenite grain boundary.The inhomogeneous microstructure causes the experimental optimum quenching temperature corresponding to maximum retained austenite fraction to be higher than the calculation based on CPE(constrained paraequilibrium) model.The product of tensile strength and total tensile elongation is 47.5 GPa%,and tensile strength of 1760 MPa was obtained for the steel with carbon content of 0.51 wt%.The TRIP(transformation induced plasticity) effects of the large fractioned metastable austenite make a main contribution to the high ductility improvement,and the martensitic matrix provides high strength.