摘要
中速船用柴油机由于其特殊需要，其缸盖螺栓和连杆螺栓的强韧性指标要求明显高于低速机（B＆W和Sulzer）的技术要求，经热处理调质后的机械性能要求为：Rm1200-1350MPa，Re≥1050MPa，A≥13％，Aku5≥40J。本文阐述了先后选用35CrNi3WA和30NCD16两种钢材的因由及其热处理调质后的机械性能结果。由试验结果可知，35CrNi3WA和30NCD16钢中的W或Mo元素虽降低了，但并没有彻底消除钢的回火脆性。通过降低钢的淬火温度，延长钢的回火保温时间，增加回火次数以及采用回火后快冷的方式都有助于提高冲击韧性。35CrNi3WA经多次调整工艺参数，虽然冲击值有所提高，但仍无法满足高强韧性的技术要求；而30NCD16钢先后做了不同淬火温度的油淬试验和降温淬CaCl2饱和水溶液试验，发现油淬试验参数稳定性较差，时好时坏，840℃淬CaCl2饱和水溶液＋550℃水冷2次的工艺不仅能够满足技术要求，并且其热处理工艺性和重现性较好，说明30NCD16可以考虑作为高强韧性螺栓的选材。
Medium speed marine diesel engine, because of its special requirement, its cylinder cover bolts and connecting rod bolts strength and toughness is obviously higher than one of the low speed marine diesel engine. The mechanical properties after hardening and tempering are： Rm 1200 - 1350MPa, Re≥1050 MPa, A≥13% ,Akus≥40 J. The reason why the two kinds of material 35CrNi3WA and 30NCD16 were selected and their mechanical properties after hardening and tempering were introduced. The tests results show that the elements W and Mo in the two kinds of material 35CrNi3WA and 30NCD16 can depress the two kinds of steel＇s temper brittleness, but it is not eliminated all over. It is helpful to improve impact toughness by reducing the temperature of hardening, prolonging the heat preservation time of tempering, adding the number of tempering and fast cooling after tempering and so on. Although 35CrNi2WA＇s impact value has been improved by rectifying technics parameters many times, it still cant satisfy the high strength and toughness requirement. The steel 30NCD16 has been done oil hardening test in various hardening pararneters ：for oil hardening bad and in＇and＇out. The technics parameter of 840℃ hardening by CaCl2 saturated solution and 550 ℃ water cooling twice not only canbe satisfied, but also it＇s better for technics capability and recurrence of the technics parameter. It is shown that 30NCD16 can be used for the material selection scope of high strength and toughness bolt.
出处
《热处理技术与装备》
2007年第1期28-31,共4页
Heat Treatment Technology and Equipment
