合金球墨铸铁的渗硼等温淬火

Boroaustempering Treatment on Alloyed Ductile Irons

热处理能明显改善球墨铸铁（以下简称球铁译注）的性能，获得等温淬火球铁（ADI ）。通过渗硼形成高硬度（2100 HV）的渗层能进一步提高性能。本文研究用球铁含有合金元素铜、铜镍和铜镍钼，在850℃、900℃和950℃的盐浴（硼砂＋铝）中渗硼2 h和4 h，然后将试样直接从渗硼温度在240℃、300℃和360℃的盐浴中等温淬火（渗硼等温淬火），渗硼后不需要为了等温淬火而再次奥氏体化加热。渗硼层均匀，厚度35～130μm，硬度1300～1700 HV。

Ductile cast iron can be heat treated to obtain a significant property improvement austempering,resulting in Austempered Ductile Iron（ADI）.Performance can be further improved by using boronized surface layer which are capable of reaching high hardness （2 100 HV）.In this work,samples of nodular cast iron alloyed with copper, copper-nickel and copper-nickel-molybdenum were borided in a salt bath （borax＋aluminum）at temperatures of 850,900 and 950 ℃ for 2 and 4 hours.After these treatments,the samples were directly austempered from the boriding temperature in salt baths at temperatures of 240,300 and 360 ℃ （boroaustempering）which avoided the need for a subsequent reheating for such processing.The boriding treatment produced uniform layers with thickness in the range 35 ~130 micrometers and hardness in the range from 1 300 to 1 700 HV.