5CrMnMo淬火加热保温时间对组织性能的影响

Influence of Holding Time on the Structure and Properties of 5CrMnMo in the Process of Quenching

研究了５ＣｒＭｎＭｏ热模钢９００℃强韧化处理时加热保温时间对组织性能的影响。试验表明，试样在９００℃加热淬火时，当保温时间少于１０ｍｉｎ时淬火组织以针状马氏体为主，当保温时间大于３５ｍｉｎ后淬火组织主要是由板条马氏体组成，随着保温时间不断延长，纯板条束中的孪晶区也将不断减少，回火后的冲击韧性值及断裂韧性值有很大提高，研究指出，当５ＣｒＭｎＭｏ热模钢９００℃加热保温６０ｍｉｎ左右淬火后于５２０℃下回火３ｈ时可获最佳综合机械性能，这不但超过传统工艺而且优于复合等温处理工艺。

Influence of holding time on the structure and properties of hot die steel 5CrMnMo has been studied when strengthening and malleablizing treated at 900℃. Tests have shown that when samples are heated and quenched at 900℃, if holding time is less than 10 minutes,the structure primarily consists of acicular martensite; while holding time is more than 35 minutes, the structure is mainly of lath martensite. With the increasing of holding time, the twin zone in pure lath martensite decreases. And the impact strength of notched bar and fracture toughness after tempering enhance a lot. Authors suggest that hot die steel 5CrMnMo can possess optimal and combined mechanical property when held 60 minutes or so at 900℃ and then tempered 3 h at 520℃. Comparatively speaking, this technology is superior not only to traditional. technologies but also to compound isothermal treatment technology.