共查询到18条相似文献,搜索用时 125 毫秒
1.
目的为了改善45钢表面状态,提高其表面性能,采用CO2激光器对其表面进行激光相变硬化处理。方法利用带有能谱的扫描电子显微镜(SEM/EDS)、盐雾试验机等,对激光相变硬化层组织及耐蚀性能进行了观察和分析。结果激光相变硬化层由熔化区、相变硬化区和热影响区三部分组成,其组织依次为:混合马氏体+未溶碳化物、针状马氏体、残余奥氏体。随扫描速度增加,耐蚀性先变好而后变差。结论激光相变硬化处理可改善45钢的表面性能,显著提高其耐蚀性能。 相似文献
2.
对三种含砷量的30CrMnSiA钢进行了不同温度的回火处理,在室温下测取了回火处理试样的穆斯堡尔谱,同时对典型试样作了金相和俄歇电子能谱(AES)分析。试验结果表明。30CrMnSiA钢经淬火十回火处理后,其室温组织为α'固溶体、碳化物和少量残余奥氏体的混合组织。回火温度不同,碳化物的形态也不一样,残余奥氏体含量随回火温度升高而降低。低温回火脆性主要是残余奥氏体分解与ε+θ碳化物析出综合作用的结果。 相似文献
3.
高速钢激光相变强化组织的回火稳定性 总被引:1,自引:0,他引:1
研究了W18Cr4V高速钢激光相变强化层的组织及其回火稳定性。结果表明,对于W18Cr4V高速钢,激光相变强化后的组织明显细化,其组织由马氏体,残余奥氏体及末溶碳化物组成,W,Cr,V等强碳化物形成元素在马氏体及残余奥氏体中固溶度的提高使强化层的回火稳定性有了明显的改善,经640℃回火后强化层硬度达到最高值1003HV0.1,红硬性的提高改善了高速钢刀具的切削性能。 相似文献
4.
40Cr钢试样经不同热处理后在空气中用CO2连续激光束进行辐照,以穆斯堡尔谱学研究试样在辐照后的组织结构变化。试验结果表明,调质预处理后再进行激光辐照的试样,不仅残作产奥氏体含量较低,而且其中碳的含量最低。 相似文献
5.
6.
Cr12MoV钢CD渗碳后马氏体形态的研究EI 总被引:1,自引:0,他引:1
本文采用扫描电镜和透射电镜分析了Cr12MoV钢CD渗碳淬火后碳及合金元素的微区成分、表层与心部的组织形态及其对力学性能的影响。经观察,尽管Cr12MoV钢名义含碳量很高,但CD渗碳淬火后渗层及心部的马氏体仍是以位错马氏体为主的混合马氏体。这种类型的马氏体和残余奥氏体及其中弥散分布的碳化物构成的渗层—复相组织,显著提高了钢的强韧性。 相似文献
7.
8.
9.
采用盐浴法对热成形钢22MnB5进行了Q&P工艺(quenching and partitioningprocess)处理,研究了淬火终点温度、分配温度和分配时间对试验钢的显微组织、力学性能和残余奥氏体含量的影响。结果表明:Q&P工艺处理22MnB5钢的显微组织主要为马氏体和残余奥氏体组织,同时有一定量的碳化物析出,随着淬火终点温度和分配温度的升高或分配时间的延长,马氏体和碳化物的微观形貌会发生变化;在淬火终点温度和分配温度为325℃,分配时间为60s时得到的试样强塑积最高,达到20435MPa.%;试样的拉伸断口都显示出良好的韧性断裂特征;XRD分析表明,在Q&P工艺处理后试验钢的残余奥氏体含量可达5.5%。 相似文献
10.
30CrMnSiA和30CrMnSiNi2A钢超高温淬火组织与性能的研究 总被引:3,自引:0,他引:3
研究了30CrMnSiA、30CrMnSiNi2A钢超高温淬火组织与力学性能关系。试验结果表明,在该钢Ac3以上-200℃超高温淬火可获得组织细小均匀的板条马氏体加残余奥氏体。控制超高温淬火加热保温时间,毁唯奥氏体化又能获得细小奥氏体晶粒,从而显著提高了该钢的强韧性。 相似文献
11.
NungheeRYU SunggoonKANG 《材料科学技术学报》2002,18(1):17-20
The effects of laser hardening parameters such as beam power,beam diameter and scanning rate on microstructure and mardness of 9CrSi steel were investigated.The microstructure of the surface layer of 9CiSi steel was changed from pearlite to martensite,retained austenite and carbide by laser hardening .The depth of the hardened layer increased with increasing laser energy density and the surface hardeness increased by 3-5times as high as the untreated steel.The laser hardened surface had good wear resistance due to martensite and carbide in the surface layer.The wear mode at low speed was abrasive,while the wear mode at high speed was adhesive. 相似文献
12.
B Sasmal 《Journal of Materials Science》1997,32(20):5439-5444
The plate-like morphology of M23C6 carbide precipitated around undissolved NbC particles in a stabilized austenitic stainless
steel has been studied by transmission electron microscopy. This precipitation occurred during high temperature ageing of
the specimens which had previously been quenched in water from 1550 K. These carbide plates that are characterized by {111}-
and {101}-type interfaces have a cube-cube orientation relationship with austenite and lie on {110} austenite planes. Such
precipitation was not commonly observed in specimens that were deformed prior to ageing. The possible mechanisms for the nucleation
and growth of these precipitates are discussed.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
13.
《Materials Science & Technology》2013,29(5):452-457
AbstractThe effects of laser surface hardening on AISI 01 tool steel samples were studied by changing the laser operating parameter combinations and the initial steel microstructure. Both melted and solid state transformed regions were produced, and then studied using optical microscopy, analytical electron microscopy, X-ray diffraction, and measurements of micro hardness to investigate the hardening mechanisms and the development of compressive residual stresses. The results indicate that hardened case depths up to 0·6 mm can be obtained using a laser beam operated at a power of 500 W and a scan rate of 2·1 mm s?1, but that different amounts of retained austenite and undissolved carbides are observed for different beam powers. Quenched and tempered AISI 01 steel samples, with initial hardness values in the range 30–40 HRC, are better suited for laser surface hardening compared with the samples with initial hardness of 48–50 HRC, because the formation of an over tempered region adjacent to the hardened zone can be avoided.MST/901 相似文献
14.
15.
本文主要采用X射线法对激光相变硬化处理后试样表面至内部的残余应力进行逐层测定。并辅以小孔应力释放法予以比较。结果表明:在通常激光相变硬化处理参数下,碳钢的残余应力按正弦波规津分布。表面为压应力,内部为拉应力。其幅值随激光参数减小而减小。二次激光相变硬化处理的残余应力为拉应力。本文对残余应力在激光相变硬化处理热循环过程中的形成进行了解释。在最初升温阶段,表面发生热塑性变形而形成少量压应变。在随后的冷却过程中产生拉应变。当发生奥氏体向马氏体组织转变时,又产生压应变。因此,最终残余应力状态是表面达到的温度,塑性屈服量,组织转变量等因素综合影响的结果。而与是终形成的组织,残余奥氏体量等没有对应关系。 相似文献
16.
Yong Wang Mei Yan Li Bin Han Tao Han Yi Yuan Cheng 《Journal of Materials Science》2010,45(13):3442-3447
The influence of secondary carbides precipitation and transformation on the secondary hardening of laser melted high chromium
steels was analyzed by means of scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The
microstructure of laser melted high chromium steel is composed of austenite with supersaturated carbon and alloy elements
and granular interdendritic carbides of type M23C6. Secondary hardening of the laser melted layer begins at 450 °C after tempering, and the hardness reaches a peak of 672HV
at 560 °C and then decreases gradually. After tempering at 560 °C, a large amount of lamellar martensite was formed in the
laser melted layer with a small quantity of thin lamellar M3C cementite due to the martensitic decomposition. The stripy carbides precipitating at the grain boundaries were determined
to be complex hexagonal M7C3 carbides and face centered cubic M23C6 carbides. In addition, the granular M23C6 carbides and fine rod-like shaped M7C3 carbides coexisted within the dendrites. As a result, the combined effects of martensitic transformation, ultrafine carbide
precipitations, and dislocation strengthening result in the secondary hardening of the laser melted layer when the samples
were tempered at 560 °C. 相似文献
17.
采用定量金相的方法研究GCr15轴承钢在球化退火、奥氏体化淬火、低温回火等不同热处理工序后其碳化物的演变行为,通过ThermoCalc软件进行数值模拟计算分析碳化物尺寸和成分对其在奥氏体化时固溶动力学的影响。结果表明:球化退火处理后形成的碳化物粒子尺寸呈多峰分布,奥氏体化和回火后的碳化物粒子尺寸分布为单峰分布,奥氏体化后碳化物中Cr含量略有增加;Cr含量高的碳化物粒子具有较大尺寸;球化退火形成的碳化物在奥氏体化时大量固溶形成了富碳奥氏体,淬火后转变为高碳马氏体并导致高硬度;奥氏体化时碳化物固溶发生Cr的配分导致碳化物中Cr含量增加;直径200nm的碳化物即使其Cr含量接近基体成分,也不能在奥氏体化热处理时完全固溶,未溶的碳化物颗粒将影响后续回火过程的碳化物析出。 相似文献
18.
Features of the structure of R6M5 steel based coatings obtained by multiscan electron-beam fusion of a hardening composition
in vacuum have been studied. It is established that the carbide subsystem of the hardened layer is characterized by a multimodal
distribution of carbide particles with d
1 = 3.8 μm, d
2 = 0.65 μm, and d
3 < 0.25 μm. The volume fraction of M6C secondary carbide and retained matrix austenite can be controlled within broad limits by varying thermal parameters of the
electron-beam fusion. An increase in the retained austenite fraction in the coating leads to improved wear resistance due
to the γ → α′ marten-site transformation during friction and the presence of dispersed secondary carbides inside the matrix
grains. 相似文献