奥氏体不锈钢低温离子渗氮工艺研究

对304、316 L奥氏体不锈钢进行了不同温度、不同时间的离子渗氮。研究了渗层的显微组织和耐腐蚀性,测定了渗层的硬度。结果显示,随着渗氮温度的升高,两种钢渗层的表面硬度和深度都增加,而耐蚀性降低。渗氮温度≥400℃时,随着渗氮时间的延长,两种钢渗层的表面硬度变化不大,但深度明显增加,渗层的耐蚀性降低。当渗氮工艺相同时,316 L钢渗氮层的硬度、深度和耐蚀性均比304钢的渗氮层高。     

温度对AISI304奥氏体不锈钢离子渗氮的影响

对AISI304奥氏体不锈钢进行脉冲电流辉光离子渗氮处理,在不同处理温度(480 ℃、520 ℃、580 ℃)下渗氮8 h后,获得了一定厚度的渗氮层.通过对渗层进行金相分析和硬度测试表明,随着渗氮温度升高,渗层厚度增大,显微硬度先增大后减小.综合温度对渗层厚度与显微硬度的影响,AISI304奥氏体不锈钢卡套辉光离子渗氮温度可采用520 ℃,渗氮后渗层厚度为90 μm,显微硬度为1317 HV0.1.     

渗氮温度对奥氏体不锈钢性能的影响

利用自行研制的直流脉冲离子渗氮设备对奥氏体不锈钢进行离子渗氮,采用显微硬度计、倒置金相显微镜等手段研究了渗氮温度对奥氏体不锈钢显微硬度、金相组织、耐磨性能和耐腐蚀性能的影响.结果表明,通过离子渗氮处理得到的渗层表面硬度均在1150 HV0.05以上,耐磨性能提高4～5倍,低温离子渗氮在提高耐磨性能的同时保持其耐腐蚀件能基本不变.     

低温离子渗氮时间对304不锈钢渗层的影响

对304奥氏体不锈钢进行400 ℃不同时间的离子渗氮处理.利用光学显微镜、轮廓仪、能谱仪、X射线衍射仪和显微硬度计研究了经渗氮处理后试样改性层的表面形貌、微观结构、相组成和性能等.结果表明,随着渗氮时间的延长,试样表面的粗糙度、渗层厚度、表面氮含量、显微硬度基本呈线性增加;X射线衍射分析表明,在400 ℃不同时间的渗氮层为单一S相,并无CrN相析出.     

工件电位对奥氏体不锈钢活性屏离子渗氮的影响

用活性屏离子渗氮技术分别对处于悬浮电位和阳极电位的AISI 316L奥氏体不锈钢进行低温渗氮处理.并对渗氮层的组织、形貌、相结构、显微硬度和耐蚀性能进行分析.结果表明,在这两种电位状态下处理的试样均可获得具有S相结构特征的单相硬化层.渗氮层不仅具有高的硬度,还有良好的耐蚀性能.在活性屏离子渗氮过程中,从活性屏上溅射下来的中性S相粒子也可以起到氮载体的作用.活性屏空间中性粒子和电子的撞击足以消除不锈钢表面钝化膜对氮的阻隔作用.     

奥氏体不锈钢低温低压等离子体渗氮

利用低了子体弧源离子渗氮技术,在低压（４×１０＾－１Ｐａ）、低温（３５０～４００℃）条件下进行奥氏体不锈钢表面渗氮处理,可在奥氏体不锈钢表面形成硬度高、耐蚀性好、厚度１０μｍ左右的向氏体中的过饱和固溶体氮化层,最高表面氮浓度达到４５％左右     

提高奥氏体不锈钢磨损和腐蚀抗力的渗氮

渗在制造工业的各种部门得到广泛应用，借以改善奥氏体不锈钢表面的抗擦伤性能。可是，渗氮虽提高其耐磨性，但耐蚀性却下降，自八十年代中期以来，不锈钢的渗有了重大进展，现在，可以获得同时改善耐磨和耐蚀的渗氮层，本文重点介绍了该领域的最新进展，并气体渗氮和离子渗氮层的组织与性能，通过控制工艺参数，可获得各种渗氮层组织，低温渗氮可获得硬度超过１４００ＨＶ的单相渗氮层，并显著改善其耐腐蚀性能。     

奥氏体不锈钢高频高压低温等离子体渗氮

利用浸没式高频高压等离子体渗氮（ＩＨＨＰＮ）技术对ＳＳ３０４奥氏体不锈钢进行了低温渗氮处理。在３００℃×２５ｈ处理条件下获得了０３μｍ厚的高氮层。表面显微硬度较未处理的样品明显提高。ＸＲＤ分析表明,改性层内形成了膨胀奥氏体。认为大的有效电流密度是快速离子渗氮的关键     

奥氏体不锈钢稀土催渗离子渗氮工艺研究

对304、316L奥氏体不锈钢采用不同氮一氢比的气氛,在不同温度和不同保温时间进行了离子渗氮和稀土催渗离子渗氮。结果表明,经580℃在氮一氢比为1：3的气氛中稀土催渗离子渗氮9h,304和316L钢的渗层深度分别为0．12mm和0．112mm,表面硬度达1000HV0．1左右,与常规离子渗氮工艺相比,渗氮时间缩短了1h。     

奥氏体不锈钢耐蚀渗氮工艺的研究

对AISI 321和AISI 304不锈钢进行了低温离子渗氮,其表面获得了均匀的渗氮层即白亮层。与未经渗氮的钢相比,经离子渗氮的钢表面硬度和耐磨性显著提高,而耐蚀性也并不降低;与经传统的盐浴氮碳共渗的钢相比,经离子渗氮的钢的耐磨性和耐蚀性也均有所提高。对经低温离子渗氮的AISI 321纲渗层进行了XRD分析,发现试样的谱峰明显向低角度偏移。     

Plasma nitriding of AISI 304 austenitic stainless steel with pre-shot peening

AISI 304 austenitic stainless steel was plasma nitrided at the temperature ranging from 410 to 520 °C with pre-shot peening. The structural phases, micro-hardness and electrochemical behavior of the nitrided layer were investigated by optical microscopy, X-ray diffraction, micro-hardness testing and anodic polarization testing. The effects of shot peening on the nitride formation, nitride layer growth and corrosion properties were discussed. The results showed that shot peening enhanced the nitrogen diffusion rate and led to a twice thicker nitrided layer than the un-shot peening samples under the same plasma nitriding conditions (410 °C, 4 h). The nitrided layer was composed of single nitrogen expanded austenite (S-phase) when nitriding below 480 °C, which had combined improvement in hardness and corrosion resistance.     

离子渗氮温度对Fe-C-Cr-Ni-Mn-V沉淀硬化型奥氏体不锈钢渗层组织和性能的影响

采用离子渗氮工艺对一种Fe-C-Cr-Ni-Mn-V沉淀硬化型奥氏体不锈钢进行表面改性处理。利用光学显微镜(OM)、X射线衍射(XRD)、电子探针显微分析仪(EPMA)和维氏硬度计对不同离子渗氮温度下渗层的组织和性能进行了研究。结果表明,Fe-C-Cr-Ni-Mn-V沉淀硬化型奥氏体不锈钢经430~520 ℃离子渗氮处理10 h后,试样表面均形成一层厚度均匀的渗氮层,表面硬度显著增大。随着离子渗氮温度的升高,渗层厚度增大,520 ℃渗氮时渗层厚度达到78 μm。当渗氮温度为430 ℃时,渗层表面主要由γ_N+CrN+γ′-Fe₄N相组成;当渗氮温度升高至520 ℃时,渗层表面主要由γ′-Fe₄N+CrN+ε-Fe_2-3N相组成。在3种渗氮温度下,渗层中均有CrN析出,导致渗层耐蚀性低于基体组织。     

Surface modification of austenitic stainless steel with plasma nitriding for biomedical applications

In the present study, plasma nitriding of AISI type 303 austenitic stainless steel (SS) specimens was performed using a microwave system. The nitrided layers were characterized by performing scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and a Vickers microhardness test. The antibacterial activities of the nitrided layers were evaluated. XRD and TEM showed that a single γ_N phase was formed by plasma nitriding at the plasma power of 700 W and 450 °C. The analytical results demonstrated that the hardness of type 303 specimens could be enhanced by plasma nitriding because of the formation of the γ_N phase. A bacterial test also demonstrated that the nitrided layer exhibited excellent antibacterial properties.     

奥氏体不锈钢循环离子氮氧共渗工艺研究

对OCr18Ni9奥氏体不锈钢进行氮氧共渗循环离子渗氮试验,并和常规离子渗氮进行对比.利用光学显微镜、显微硬度计、XRD及磨损仪对渗氮层进行分析.结果表明,氮氧共渗循环离子渗氮比常规离子渗氮的渗氮速度快,渗层比常规离子渗氮厚;表面硬度为920 HV0.05(比常规离子渗氮高20 HV0.05),硬度梯度平缓;渗层中的ε相减少,γ'相增多;且渗层中的微量Fe3O4降低了表面摩擦系数,使工件经氮氧共渗循环离子渗氮后获得更高耐磨性.     

气压对904L奥氏体不锈钢低温离子渗氮组织与耐蚀性能的影响

通过辉光离子低温渗氮对904L超级奥氏体不锈钢(904Lss)进行表面改性处理,采用扫描电镜、X射线衍射仪(XRD)、电化学方法等研究了渗氮后试样的表面形貌、显微组织结构、硬度以及耐蚀性能。结果表明:100 Pa渗氮后的试样形成了强化相γN相,大大提高了904L不锈钢试样的表面硬度,高达1400 HV0.1;150 Pa渗氮后的试样产生了强氮化物CrN,其耐蚀性远远低于原始904L奥氏体不锈钢。     

Influence of plasma nitriding on hydrogen environment embrittlement of 1.4301 austenitic stainless steel

The aim of this work was to study if hydrogen environment embrittlement of DIN 1.4301 austenitic stainless steel can be suppressed by a nitrided surface. DIN 1.4301 was plasma nitrided in a N₂/H₂ discharge. Nitriding produced 3-layered structure consisting of a γ_N top layer, an intermediate γ/γ_C-layer and a diffusion layer. It is assumed that the γ_C phase was formed due to the decomposition of CO originating from the reactor walls and the subsequent incorporation of C into the material. The γ_C phase is characterized by distinct XRD peaks and carbon contents between 0.5 and 4 wt.% as well as nitrogen contents between 0.5 and 8 wt.%. Plastic deformation of the plasma nitrided specimen showed cracks and some delamination of the γ_N layer, whereas the γ/γ_C-layer behaved in a very ductile manner. Even at a plastic deformation of 35% no cracks or any other damage was visible. A tensile test in gaseous hydrogen showed severe embrittlement of the unnitrided steel and the nitrided steel with a γ_N layer. No cracks were observed in areas where just the γ/γ_C-layer was present.     

离子硬化工艺在316L不锈钢阀内件中的应用

对316L奥氏体不锈钢进行离子渗氮(PN)和离子碳氮共渗(PNC)处理,利用光学显微镜、显微硬度计、电化学工作站、粗糙度检测仪和三坐标测量仪对试样渗层厚度、显微硬度、耐腐蚀性、表面粗糙度和变形量进行讨论分析。结果表明:316L钢经离子碳氮共渗处理后的渗层硬度分布较好,可提高耐腐蚀性能。离子碳氮共渗技术可应用于阀内件(包括球芯和阀座)的表面硬化处理,在保证零件尺寸配合公差的条件下,大幅提高阀内件的表面硬度。     

Influence of plasma nitriding on plain fatigue and fretting fatigue behaviour of AISI 304 austenitic stainless steel

AISI 304 austenitic stainless steel samples were plasma nitrided at 420 °C for 6 h in vacuum atmosphere by glow discharge technique, in the presence of nitrogen gas. Plain fatigue and fretting fatigue tests were carried out on unnitrided and plasma nitrided samples. Plasma nitrided samples exhibited higher surface hardness, compressive residual stresses at the surface and lower surface roughness compared with unnitrided samples. However, plasma nitrided samples exhibited inferior plain fatigue and fretting fatigue lives compared with unnitrided samples. This was attributed to segregation of chromium at the grain boundaries of plasma nitrided specimens which might have weakened the regions near grain boundaries resulting in early crack initiation and accelerated crack propagation.     

Improving the surface properties of A286 precipitation-hardening stainless steel by low-temperature plasma nitriding

Plasma nitriding over a wide range of treatment temperatures between 350 and 500 °C and time from 5 to 30 h on A286 austenitic precipitation-hardening stainless steels has been investigated. Systematic materials characterisation of the plasma surface alloyed A286 alloy was carried out in terms of microstructure observations, phase identification, chemical composition depth profiling, surface and cross-section microhardness measurements, electrochemical corrosion tests, dry sliding wear tests and corrosion-wear tests. Experimental results have shown that plasma nitriding can significantly improve the hardness and wear resistance of A286 stainless steels owing to the formation of nitrogen supersaturated S-phase; the surface layer characteristics (e.g. microstructure, case depth and hardness) of the plasma surface alloyed cases are highly process condition dependent and there are possibilities to provide considerable improvement in wear, corrosion and corrosion-wear resistance of A286 steel.