25Cr3Mo3NiNb二次硬化钢冲击性能的研究

在退火奥氏体量>50%,即铁素体量<50%时,两种钢的伸长率相同。这就是说,较高的硅含量,在使No.1钢强度提高的同时,并不使其塑性降低。可以推测,由于No.1钢中残留奥氏体的含碳量较No.2钢高,使其残留奥氏体较稳定,这样,残留奥氏体在较大的变形时才发生形变诱发相变,从而导致塑性不下降。对推测的证实,有待于进一步试验

。

图7　试验钢力学性能随退火奥氏体量变化

Fig.7　Fraction of intercritical austenite vs.mechanical properties of the test steels

5　结论

(1)硅含量分别为115%和110%的低碳硅锰

TRIP 钢,随两相区退火温度的升高,它们的残留奥氏体量和残留奥氏体含碳量都上升;它们的屈服强度和抗拉强度都上升,前者的伸长率下降,后者的伸长率在760℃时有最大值。

(2)硅含量降至110%时,对钢的残留奥氏体量没有影响,但是降低了残留奥氏体中的碳含量。

(3)两种钢可以达到相近的最大强塑积值,为22000MPa %左右。但是,硅含量的降低使得获得最大强韧性值的退火温度范围缩小了,分别为760℃～800℃之间和760℃～780℃之间。

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25Cr3Mo3NiNb 二次硬化钢冲击性能的研究

王毛球1,董　瀚1,王　琪1,李建新2,赵　隆3

(11钢铁研究总院,北京100081;21抚顺特殊钢有限责任公司,辽宁抚顺　112001;

31重庆长安汽车公司,重庆　400023)

摘要:研究了二次硬化钢25Cr3Mo3NiNb 的冲击韧度随回火温度和试验温度的变化。结果发现,试验钢在200℃回火时冲击韧度较高,300～600℃回火时冲击韧度值较低,600℃以上回火时冲击韧度值迅速升高,640℃回火时冲击韧度达到最高值55J /cm 2,640℃以上回火时冲击韧度值有所降低。640℃回火后试验钢的

冷脆转变温度为10℃,屈服强度为960MPa ,可以满足兵器特种结构件高强度高韧性的要求。关键词:二次硬化钢;冲击韧度;冷脆转变

中图分类号:TG 115.5+6 文献标识码:A 文章编号:025426051(2003)0320014204

Impact Toughness of Secondary H ardening Steel 25Cr3Mo3Ni Nb

WAN G Mao 2qiu 1,DON G Han 1,WAN G Qi 1,L I Jian 2xin 2,ZHAO Long 3

(11Central Iron &Steel Research Institute ,Beijing 100081,China ;21Fushun Special Steel Co.Ltd ,Fushun Liaoning 112001,China ;31Chongqing Chang ’an Automobile Co.Ltd ,Chongqing 400023,China )Abstract :The variations of impact toughness with tempering temperature and test temperature for secondary hardening steel 25Cr3Mo3NiNb were studied.It is found that the experimental steel has a relatively higher impact toughness when tempered at 200℃,then a lower impact toughness at 300～600℃,and a peak impact toughness of 55J /cm 2at 640℃.In addition ,when tempered at 640℃,the ductile 2brittle transition temperature (DB TT )is