冷塑变对氮在38CrMoAlA钢中扩散激活能的影响

将冷压３０％与未变形的３８ＣｒＭｏＡｌＡ钢试样在不同温度下进行不同时间的气体渗氮。利用扫描电镜对试样进行波谱分析，由碳浓度曲线精确确定了渗氮层深。利用公式ξ＾ｎ＝Ｋ０．ｅ＾－Ｑ／ＲＴτ，计算了未变形与３０％变形度试样氮的扩散激活能。最后，借助电镜对试验结果进行了初步探讨。     

2Cr13钢的表面气体渗氮处理

用光学金相显微镜、扫描电子显微镜、X射线衍射(XRD)仪及显微硬度计对经气体渗氮处理的2Cr13钢试样进行了组织结构分析,并利用销-盘摩擦磨损试验机对渗氮的盘与未渗氮销摩擦副进行摩擦磨损试验.结果表明,520℃×20 h渗氮可使2Cr13马氏体不锈钢的渗氮层深度达到165 μm,处理后试样的显微硬度约为处理前的2.5倍.处理后试样的耐磨性能得到了较大的提高,渗氮盘试样的磨损表面未出现裂纹,而未渗氮销的磨损表面存在严重的裂纹.     

工具钢渗氮后的韧性和抗弯性能

最近，对经渗氮和未渗氮的AISI H13、AISI D2、K340、AISI D6和AISI M2等工具钢进行了详细的研究。采用了不同的渗氮工艺，包括气体渗氮、液体渗氮以及液体渗氮＋扩散处理，并进行了对比。对这些钢进行了弯曲试验和冲击试验，以评定其性能。用光学金相技术表征其显微组织。渗氮处理会降低无缺口冲击试样的断裂模数和冲击吸收功。由于扩散层较深，导致经气体渗氮处理的试样的力学性能下降。通过扩散处理来减薄液体渗氮试样的白亮层厚度并不会影响试样的力学性能。试验结果表明，渗氮对工具钢的最有害的影响是使冲击试验的冲击吸收功降低。     

氢对锻态Ti－25Al－10Nb－3V－1Mo合金热压缩行为的影响

利用等温压缩方法研究了氢对Ｔｉ_３Ａｌ基的Ｔｉ－２５Ａｌ－１０Ｎｂ－３Ｖ－１Ｍｏ锻态合金热变形行为的影响。在９００～１０００℃范围内，氢含量为０．２％的试样可使峰值流变应力比未氢化试样降低２５％～３１％，即相当于降低热压缩温度将近５０℃。相同温度变形的试样中氢含量增加所产生的组织变化与在更高温度压缩后所产生的组织变化相当。     

冷轧预处理对TC4合金540 ℃渗氮组织的影响

TC4钛合金经820 ℃固溶处理及室温下冷轧得到10%、20%、30%、40%、50%不同变形量的试样,之后在540 ℃进行渗氮复合时效处理8 h。利用光学显微镜、X射线衍射仪、扫描电镜等分析了不同变形量下合金渗氮组织和时效组织的变化特点以及渗氮试样表面的相结构和形貌的变化。试验结果显示,渗氮处理后,试样表面生成了TiN、Ti₂N等高硬的氮化物颗粒,变形量越大,试样表面生成的氮化物颗粒越多且尺寸越大;经固溶处理后,TC4合金的室温组织为α相+亚稳β相,经渗氮复合时效处理后,亚稳β相分解为α相,同时α相向β相转化,变形量越大,析出的β相越多,且这种趋势不如单纯的时效处理明显。     

预变形对40Cr钢渗氮层耐磨耐蚀性能的影响

研究了预变形对40Cr钢渗氮层组织、耐磨、耐蚀性能的影响。渗氮前对试样调质处理,再进行变形量分别为:10%、20%、30%的预变形,装入渗氮罐,在600℃下渗氮4 h,随炉缓冷。利用光学显微镜、X射线衍射仪、洛氏硬度计、摩擦磨损实验机和化学工作站等分别测试渗氮层的显微组织、相组成、硬度、耐磨性能和耐蚀性能。结果表明:预变形后渗氮层厚度明显增加,且变形量为10%试样的渗氮层厚度变化相对平稳;硬度随变形量的增加逐渐增大;耐磨、耐蚀性能随变形量的增加而变差,变形量为10%的试样的耐磨、耐蚀性能最好。     

冷变形促渗低温等离子渗氮对Ti6Al4V合金力学性能和显微组织的影响（英文）

针对Ti6Al4V合金低温渗氮的问题,设计了一种渗氮工艺,研究了该工艺对Ti6Al4V合金组织和力学性能的影响。通过变形增强渗氮动力,使渗氮可以在较低温度(500°C)下实现,氮化与Ti6Al4V合金基体的弥散强化同时进行。实验过程为固溶强化→室温下冷轧变形→500°C低温渗氮。结果表明,在渗氮一段时间后,试样表面形成了白亮的氮化层并且趋于稳定,变形量和变形时间对氮化层的影响不明显。试样基体组织时效效果明显,表面硬度与基体组织硬度随变形量增加而增加。经XRD物相分析,试样表面生成的氮化物为Ti N、Ti_2N、Ti_4N_(3-X)和Ti_3N_(1.29),横截面氮化物为Ti_3N_(1.29)和Ti N_(0.3)。对经过变形、渗氮和时效等工艺的试样进行摩擦磨损实验,渗氮试样的耐磨性最好。     

氢对锻态Ti—25Al—10Nb—3V—1Mo合金热压缩行为的影响

利用等温压缩方法研究了氢对Ｔｉ３Ａｌ基的Ｔｉ－２５Ａｌ－１０Ｎｂ－３Ｖ－１Ｍｏ锻态合金热变形行为的影响。在９００－１０００℃范围内，氢含量为０．２％的试样可使峰值流变应力比未氢化试样降低２５％－３１％，即相当于降低热压缩温度将近５０℃。相匠试样中氢含量增加所产生的组织变化与在更高温度压缩后所产生的组织变化相当 。     

热轧变形对快凝Al－Fe－V－Si粉热挤合金断裂行为的影响

研究了不同热变形条件下用快餐Ａｌ—Ｆｅ—Ｖ—Ｓｉ合金粉挤压成形样品的拉伸断裂行为．结果表明，在沿轧制方向拉伸的试样中，与板面平行的颗粒界面（ＬＴ界面）处形成的微裂纹不影响主裂纹的扩展，沿与板材纵截面平行的颗粒界面（ＬＳ界面）的开裂可能导致试样反常断裂，沿与板材横截面平行的颗粒界面（ＴＳ界面）则易成为主裂纹的低能扩展路径，使试样沿颗粒断裂．热轧变形使粉末ＬＳ，ＴＳ界面的强度提高快于ＬＴ界面，导致热轧变形至一定程度（３０％变形量）时试样的断裂方式改变．断裂强度与延伸率的不同变化规律与断裂方式的改变及其后的形变硬化有关．     

时效硬化钢渗氮的尺寸变化

研究了时效硬化钢渗氮尺寸变化特点,并与调质钢进行了对比。结果表明,时效硬化钢渗氮尺寸变化稍大于调质钢,这与时效硬化钢渗氮硬化和基体时效硬化的叠加效应有关。合理地利用这种叠加效应,在渗氮前进行预时效,可实现渗氮层强化的同时实现对渗氮件尺寸变化的控制。20CrNi3Mn2Al时效硬化钢齿轮试样固溶处理后经630~650 ℃×4 h预时效+520 ℃×40 h离子渗氮,渗氮径向尺寸增量0.056 mm,变形率为0.03%,与42CrMo调质钢渗氮径向尺寸增量0.043 mm,变形率0.02%相近。     

4Cr2MoWVNi钢离子渗氮工艺研究

通过对4Cr2MoWVNi钢进行离子渗氮工艺处理，研究了温度、时间对渗层组织、耐磨性能的影响。结果表明，采用合适的处理温度和时间，可以得到最佳的渗氮层深及表面硬度，在保证一定的渗氮层深条件下，4Cr2MoWVNi钢的热耐磨性能明显提高，使模具使用寿命大幅度提高。     

IMPROVING THE SURFACE PROPERTY OF TC4 ALLOY BY LASER NITRIDING AND ITS MECHANISM

The mixing technology of laser and heated nitrogen was applied to improve the surface hardness of titanium alloy (TC4). The samples were nitrided with laser power density 0f 6.5×105W·cm-2, the scanning speed various from 100 to 500mm · mm-1. The nitrogen gas was pre-heated to 300℃ to accelerate the nitriding process. Some interested samples were tested with XRD method (X-ray diffraction) to analyze the composition of nitrides, and the surface hardness of HV was measured. The results show that TiN and Ti2N were formed on the surface of Ti alloy with proper nitriding parameters, but TiN is the main composition. The surface hardness increased by three times, which is from the original value of 269 to 794kg· mm -2. The mechanism of the mixing technology is considered mainly of the activation of nitrogen by laser power and the pre-heated process which accelerated the nitriding process. The nitridation process can be considered as six steps given in detail. The result by analyzing the mechanism of improving the surface property of TiAl alloy shows the improvement of surface property due to two factors: the first reason is the result of laser annealing, and the second one is the formation of TiN.     

Ta等离子体渗氮的非平衡热力学

讨论了Ta表面等离子体渗氨的热力学问题，将超平衡氢和非平衡热力学的反应耦合理论引入离子渗氮反应的计算，从理论上解释了等离子体和氢在Ta表面渗氮过程中的作用，给出了渗氮条件下的Na-N-O非平衡定态相图，与实验验结果符合得较好，实验表明，氢和等离子体的存在，有利于提高氮原子的活度，促进热力学上不稳定的Ta的氮化物的形成，抑制粗糙的Ta的氧化物的形成。     

高速钢W18Cr4V离子渗氮层组织对TiN膜与基体结合强度的影响

采用Ｗ１８Ｃｒ４Ｖ高速钢进行离子渗氮－ＰＥＣＶＤ ＴｉＮ复合处理,运用透射电子显微镜、Ｘ射线衍射仪和光学显微镜研究试样的表层组织结构。采用连续压入法研究ＴｉＮ膜与基体的结合强度,结果表明,离子渗氮能够提高膜基结合强度,通过分析渗氮层与膜－基界面的组织特点,认为ＴｉＮ膜在渗氮层上一些与其具有相同或相似晶体结构的氮化物上外延生长,以及强度较高的渗氮层对膜的支撑是基体渗氮提高膜－基结合强度的两大因素。     

高速柴油机曲轴渗氮畸变规律与控制措施

找出了高速大功率柴油机曲轴在自然放置状态下的渗氮畸变规律，分析了曲轴的形状及渗氮工艺参数对曲轴畸变的影响。采用在连杆轴颈开档处加锲铁预校正的方法成功控制了TBD620V12曲轴渗氮过程中的畸变，渗氮后第4主轴颈、第3和第5主轴颈、第2和第6主轴颈的摆差分别小于0．12mm、0．08mm、0．05mm。     

Investigation of the effects of time and temperature of oxidation on corrosion behavior of plasma nitrided AISI 4140 steel

In this paper, the effect of the time and temperature of the post oxidation process on corrosion behavior of AISI 4140 plasma nitrided steel has been studied. Plasma nitriding was carried out at 550 °C for 5 h with a gas mixture of N2/H2:3/1. The plasma nitrided samples were post oxidized for 30 and 60 min with a gas mixture of O2/H2: 1/5 at temperatures of 400 and 450 °C. The treated samples were characterized by optical microscopy, SEM, XRD, roughness testing, electrochemical polarization and salt spray testing. The X-ray analysis revealed the formation of the iron-nitride phases ε and γ′ during plasma nitriding and the iron oxide phases of magnetite and hematite through the post-oxidizing treatment. It was also demonstrated that the corrosion characteristics of the nitrided compound layer were further improved by post-oxidation treatment and that the least corrosion rate and optimum condition relative to pitting corrosion belongs to the oxidized sample at 450 °C for 30 min.     

预氧化对不同离子渗氮工艺的影响

 利用光学显微镜、显微硬度计、XRD、SEM等分析了预氧化对40CrNiMo钢离子渗氮过程的影响。结果发现:在300℃氧化1 h的40CrNiMo试样,表面生成了厚0. 4～0. 7μm、以Fe₃O₄和Fe₂O₃为主的氧化层。在随后的540℃离子渗氮过程中,当渗氮时间较短（4 h）时,试样出现渗层浅、分布不均和硬度低等缺陷;但随着渗氮时间的延长（8 h）,预氧化表现出了一定的催渗效果,同时渗层中脉状氮化物减少;当渗氮时间延长至16 h时,预氧化的催渗效果更加显著,但渗层的疏松有所增加。     

Influence of time on the microstructure of AISI 321 austenitic stainless steel in salt bath nitriding

Influence of nitriding time on the microstructure and microhardness of AISI 321 austenite stainless steel was investigated, using a complex salt bath heat-treatment at low temperature, 430 °C. Experimental results revealed that after salt bath nitriding, a modified layer was formed on the surface of substrate with the thickness ranging from 2 μm to 30 μm with changing treating time. The nitrided layer depth thickened extensively with increasing nitriding time. The growth of the nitrided layer takes place mainly by nitrogen diffusion according to the expected parabolic rate law. Scanning electron microscopy and X-ray diffraction showed that in 321 stainless steel subjected to complex salt bathing nitrided at such temperature for less than 8 hours, the main phase of the nitrided layer was expanded austenite (S phase) by large. When the treatment time is prolonged up to 8 hours and more, S phase is formed and subsequently transforms partially into CrN, and then the secondary CrN phase precipitated. With treating time prolonged, more CrN precipitates formed along the grain boundaries in the outer part. In the inside part between the some CrN and the substrate, there is still a broad single S phase layer. All treatments can effectively improve the surface hardness.     

High frequency and low voltage plasma immersion ion implantation of nitrogen on industrial pure iron at different Rf power

Traditional plasma ion immersion implantation (PIII) can effectively improve material mechanical property and corrosion resistance. But the modified layer by PIII is too thin for many industrial applications. High frequency and low voltage plasma immersion ion implantation (HLPIII) has advantages of PIII and nitriding. Comparing with traditional ion nitriding, HLPIII can obtain higher implantation energy and create a thick modified surface layer. In the present paper nitriding layers were synthesized on industrial pure iron using high frequency and low voltage plasma immersion ion implantation with different RF power (400 W, 600 W, and 800 W). The microstructure of the nitriding layers was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mechanical properties such as microhardness and wear resistance were analyzed using HXD1000 microhardness and CSEM pin-on-disk wear testing machine. The anodic polarization characteristics were measured in a 0.9% NaCl solution at room temperature to examine the corrosion resistance of the nitriding layer. The results reveal that Fe₂N, Fe₃N and Fe₄N coexist in the nitriding layer. The nitriding layer is a corrosion protective coating on industrial pure iron in 0.9% NaCl solution. The hardness, wear resistance and corrosion resistance of the nitrided layers on industrial pure iron increase with RF power.