振动对FV520B不锈钢MAG堆焊再制造成形组织结构的影响

Effect of Vibration on Remanufacturing Microstructure of FV520B Stainless Steel by MAG Surfacing Deposition Technology

摘要:

采用堆焊熔敷成形技术进行了FV520B沉淀硬化不锈钢再制造实验，在此基础上，对FV520B不锈钢MAG堆焊再制造成形组织特点进行了分析，并研究了机械振动对再制造成形组织的影响。结果显示：FV520B不锈钢MAG堆焊再制造成形组织由马氏体+碳化物沉淀硬化相组成，且沿成形高度方向组织呈周期性变化特点，具有一定的自相似分形特性；振动会一定程度上增大孪晶形成几率，对马氏体板条具有破断作用，且马氏体板条宽度随振动转速的不断增大呈先减小后增加趋势；受振动的影响，晶格畸变和各晶面择优取向性都将发生变化，但不同晶面变化规律不同；振动的加入使得（110）晶面和(211) 晶面的Bragg衍射峰峰位向低衍射角方向发生偏移，且随振动转速的不断增大，偏移量呈先增大后减小趋势，（110）晶面衍射峰半高宽宽度呈先减小后增大趋势，其晶面择优取向性则呈现先增强后减弱趋势；在0到共振转速区间内 (211) 晶面衍射峰半高宽宽度随振动转速的不断增大呈先减小后增大趋势，当振动转速大于共振转速时又呈减小趋势，但其晶面择优取向性则随振动转速的增大呈现持续增强趋势；总体上，亚共振频率振动（振动转速f=3000 r/min）对FV520B不锈钢MAG堆焊再制造成形组织结构的影响最显著。

Abstract:

The remanufacturing experiment of FV520B precipitation hardening stainless steel was carried out by using surfacing deposition technology. On this basis, the remanufacturing microstructure characteristics were analyzed and the effect of mechanical vibration on remanufacturing microstructure was studied. The results showed the following: Firstly, the remanufacturing microstructure of FV520B stainless steel by MAG surfacing deposition technology was comprised of martensite plus a carbide precipitation-hardening phase. It performed a characteristic periodical variation along the direction of forming height, which was described by certain self-similar fractal characteristics. The vibration would increase the probability of twin formation to some extent. There was also the broken effect on martensite lath that had to be taken into account. It should be noted that the width of the martensite lath decreased first and then increased with the continuous increase of the vibration rotation rate. Affected by the vibration, the lattice distortion and the preferred orientation of each crystal plane would both be changed. However, the change rule of different crystal planes was different. The Bragg diffraction peak positions of planes (110) and (211) shifted towards the direction of lower diffraction angle due to the addition of vibration. Furthermore, the offset increased first and then decreased with the continuous increase of the vibration speed. Meanwhile, the FWHM of diffraction peak (110) decreased first and then increased and the preferred orientation of this crystal plane increased first and then decreased. Within the range between 0 and the resonance speed, the FWHM of diffraction peak (211) decreased first and then increased with the continuous increase of the vibration speed and decreased again when the vibration speed was higher than the resonance speed. However, its preferred orientation continued to increase with the increase of the vibration rotation rate. In general, the sub-resonance frequency (The vibration rotational speed f=3000 r/min) had the most significant effect on the remanufacturing microstructure of FV520Bstainless steel by MAG surfacing deposition technology.