Laser surface modification of UNS S31603 stainless steel. Part I: microstructures and corrosion characteristics
Laser surface modification of UNS S31603 stainless steel. Part I: microstructures and corrosion characteristics
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DOI：
10.1016/s0921-5093(00)00929-1
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发表时间：
2000-10-15
期刊：
影响因子：
6.4
通讯作者：
Man, HC
中科院分区：
文献类型：
--
作者：
Kwok, CT;Cheng, FT;Man, HC
对奥氏体不锈钢UNS S31603进行了激光表面合金化处理，合金元素为Co、Ni、Mn、C、Cr、Mo、Si，合金/化合物为AlSiFe、Si 3 N4和NiCrSiB。在第二部分中，在3.5%NaCl溶液中，在23摄氏度的合金试样的空蚀特性进行了研究，通过一个20 kHz的超声波振动器在30 μ m的峰-峰振幅。用维氏硬度计和能谱仪分别研究了合金层的硬度分布和成分分布。AlSiFe、C和NiCrSiB合金化试样的抗空蚀性能最高，分别为基体的11.1、10.5和7.9倍。以奥氏体为主相的试样的损伤模式为韧性断裂，以铁素体或金属间化合物为主相的试样的损伤模式为脆性断裂。空蚀开始于机械性能（例如硬度）发生突变的相界，然后传播到较弱的相中。II还指出，在本研究中，不能同时实现抗空蚀性和抗腐蚀性的大幅度改善。(C)2000 Elsevier Science S.A.采用不同元素（Co、Ni、Mn、C、Cr、Mo、Si）和合金/化合物（AlSiFe、Si 3 N4和NiCrSiB）对奥氏体不锈钢UNS S31603进行激光表面合金化。通过火焰喷涂或粘贴将粉末形式的合金材料预先放置在基底的表面上。然后通过高功率激光束扫描表面以实现表面合金化。通过扫描电镜、光学显微镜和X射线衍射仪研究了合金化层的微观结构，并通过动电位极化法研究了合金化层在23 ℃ 3.5%NaCl溶液中的腐蚀特性。激光合金化表面的性能根据所使用的合金化材料的类型和量以及激光加工参数而变化。Co、Ni、Mn、C或NiCrSiB合金化的试样中含有奥氏体作为主相，C合金化和NiCrSiB合金化的试样中含有碳化物和碳化物/硼化物作为次要相。对于与Cr或Mo合金化的试样，主要相是铁素体。在Si或Si 3 N4的情况下，主相是金属间化合物Fe、Si。当使用AlSiFe时，主相可以是铁素体或Fe 3Al。这取决于稀释率。Si和Si 3 N4实现了耐腐蚀性的最大改善，分别导致170和211 mV的点蚀电位的惰性偏移，以及130和221 mV的保护电位的相应惰性偏移。对于NiCrSiB合金，稀释程度对合金耐蚀性的影响较大。对于所有其他合金材料，耐腐蚀性保持不变或恶化，主要是由于存在一些陶瓷或金属间化合物相作为点蚀起始位点。(C)2000 Elsevier Science S.A. All rights reserved.
Austenitic stainless steel UNS S31603 was laser surface alloyed with various elements (Co, Ni, Mn, C, Cr, Mo, Si) and alloys/compounds (AlSiFe, Si3N4 and NiCrSiB) as presented in Part I together with the microstructures and the corrosion characteristics of the alloyed specimens. In Part II, the cavitation erosion characteristics of the alloyed specimens in 3.5% NaCl solution at 23 degrees C were studied by means of a 20 kHz ultrasonic vibrator at a peak-to-peak amplitude of 30 mu m. The hardness profile and the compositional profile of the alloyed layers were investigated by a Vickers hardness tester and by EDX respectively. The cavitation erosion resistance of specimens alloyed with AlSiFe, C and NiCrSiB were highest, reaching 11.1, 10.5 and 7.9 times that of the substrate respectively. The damage mode was identified to be ductile fracture for specimens containing austenite as the major phase, and brittle fracture when the major phase was ferrite or intermetallic. Cavitation erosion was initiated at the phase boundaries where there was an abrupt change in mechanical properties (e.g. hardness) and then propagated into the weaker phase. II was also noted that large improvement in cavitation erosion resistance and corrosion resistance could not be simultaneously achieved in the present study. (C) 2000 Elsevier Science S.A. All rights reserved.Laser surface alloying using various elements (Co, Ni, Mn, C, Cr, Mo, Si) and alloys/compounds (AlSiFe, Si3N4 and NiCrSiB) on austenitic stainless steel UNS S31603 was attemped. Alloying materials in powder form were preplaced on the surface of the substrate by flame spraying or pasting. The surface was then scanned by a high power laser beam to achieve surface alloying. The microstructures of the alloyed layers were studied by scanning electron microscopy, optical microscopy and X-ray diffractometry, and the corrosion characteristics in 3.5% NaCl solution at 23 degrees C were studied by potentiodynamic polarisation. The performance of the laser alloyed surfaces varied depending on the type and amount of alloying materials used, and on the laser processing parameters. The specimens alloyed with Co, Ni, Mn, C or NiCrSiB contained austenite as the main phase, with carbides and carbides/borides as the minor phases in C-alloyed and NiCrSiB-alloyed specimens. For specimens alloyed with Cr or Mo, the major phase was ferrite. In the case of Si or Si3N4, the major phase was an intermetallic Fe,Si. When A1SiFe was used, the major phase could be ferrite or Fe3Al. depending on the dilution ratio. The largest improvement in corrosion resistance was achieved with Si and Si3N4, leading to a noble shift in the pitting potential of 170 and 211 mV, respectively, and a corresponding noble shift in the protection potential of 130 and 221 mV. For NiCrSiB, the effect on the corrosion resistance depended on the degree of dilution. For all the other alloying materials, the corrosion resistance either remained unchanged or deteriorated mainly due to the presence of some ceramic or intermetallic phases which acted as sites of pit initiation. (C) 2000 Elsevier Science S.A. All rights reserved.