Al对42CrMo螺栓钢淬透性及组织的影响  

Effect of Al on Hardenability and Microstructure of 42CrMo Bolt Steel

作　　者：吕超然 徐乐[1] 史超 刘进德 蒋伟斌 王毛球[1] LU Chaoran;XU Le;SHI Chao;LIU Jinde;JIANG Weibin;WANG Maoqiu(Central Iron&Steel Research Institute,Beijing 100081,China;Inner Mongolia North Heavy Industries Group Co.Ltd.,Baotou 014033,China;Ningxia Tiandi Benniu Industrial Group Co.Ltd.,Shizuishan 753001,China;Jianlong Beiman Special Steel Co.Ltd.,Qiqihaer 161041,China)

机构地区：[1]钢铁研究总院特殊钢研究所,北京100081 [2]内蒙古北方重工业集团有限公司,包头014033 [3]宁夏天地奔牛实业集团有限公司,石嘴山753001 [4]建龙北满特殊钢有限责任公司,齐齐哈尔161041

出　　处：《金属学报》2020年第10期1324-1334,共11页Acta Metallurgica Sinica

基　　金：国家重点研发计划项目No.2016YFB0300104。

摘　　要：在42CrMo钢基础成分中配合添加Al-Ti和Al-B元素,通过末端淬火实验和截面硬度实验对比分析3种42CrMo钢淬透性的差异,并通过OM、SEM等手段观察晶粒形貌以及不同部位淬火后显微组织,利用三维原子探针(3DAP)分析元素分布,通过常规力学性能实验检测其常温拉伸和低温冲击性能。结果表明,AlTi、Al-B的添加均使42CrMo钢淬透性提高,Al-B钢增加淬透性作用更大,淬火后距淬火端25 mm处的硬度增加6 HRC,直径42、48和56 mm截面的心部硬度分别增加7、10和14 HRC,并且使钢的抗拉强度Rm≥1200 MPa,-40℃下冲击吸收功KV2≥27 J,力学性能满足低温环境下螺栓用钢的使用要求。通过化学相分析实验和TTT曲线测定,表明Al-Ti配合添加,Ti发挥固氮作用形成TiN,使Al固溶于铁素体中,抑制贝氏体产生;Al-B配合添加,一部分Al发挥固氮作用,另外一部分Al与B共同固溶于钢中,抑制珠光体和铁素体的转变,增加实验用钢在较低的冷速下获得马氏体的能力,提高钢的淬透性。通过3DAP实验分析钢中各元素的分布情况,其中Al元素在钢中弥散分布,抑制C的扩散,从而抑制贝氏体的形成,提高钢的淬透性。实验结果表明,Al在钢中添加既可作为固N元素促进B的固溶,也可由其自身固溶于钢中,提高材料的淬透性。42CrMo steel has a good combination of strength and toughness after quenching and tempering treatment, which make it an ideal candidate material for high strength bolt. Nevertheless, with the increase of bolt diameter in wind power field, the hardenability of 42CrMo steel is inadequate to manufacture the high strength bolt with diameter over 36 mm. Recent study indicates that Al addition is an economical and effective way to affect the phase transformation product during quenching process. In order to improve the hardenability of 42CrMo bolt steel, the effect of Al on the hardenability of 42CrMo was investigated by Jominy test and cross section hardness distribution test. OM and SEM were used to analyze the morphology of the grain size;chemical phase analysis test was used to detect the precipitation in Al addition steels;the isothermal transformation diagram(TTT curve) was measured to study the phase transformation of the steels;the three dimensional atom probe(3DAP) was used to analyze the Al distribution in matrix;the tensile and impact toughness properties of Al addition steels were also examined. It was found that the hardenability of 42CrMo bolt steel could be improved significantly by Al-Ti and Al-B addition, the hardness was increased by 6 HRC at the position of 25 mm from quenched end, the center hardness in diameter of 42, 48 and 56 mm was increased by 7, 10 and 14 HRC, respectively. The improvement of hardenability for Al-Ti addition steel can be attributed to the increasing dissolved Al content in the matrix because of the Ti addition, which suppresses the formation of bainite during the quenching process. The hardenability of Al-B addition steel is better than that of Al-Ti addition steel, which can be ascribed to the dissolved Al and B inhibiting the phase transformation of ferrite and pearlite. Moreover, Al can play an important role in increasing dissolved B content by means of Al N formation, in which the dissolved Al dispersive distribution in matrix is favorable to improve the hardenability of

关 键 词：42CRMO钢 淬透性 3DAP 力学性能 相分析 

分 类 号：TG142.1[一般工业技术—材料科学与工程]