...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>ISIJ international >Nitriding of interstitial free steel in potassium-nitrate salt bath
【24h】

Nitriding of interstitial free steel in potassium-nitrate salt bath

机译：硝酸钾盐浴中间隙自由钢的渗氮

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

A study has been made of nitriding of interstitial free (IF) steel in the potassium-nitrate salt bath at temperatures ranging from 400 to 650 deg C. The salt is decomposed to generate nitrogen and oxygen. Nitrogen diffuses into steel, or steel is nitrided, while oxygen reacts on steel surface to form the oxide scale. The oxide scale thickness is much smaller than the nitriding thickness. Most of nitrogen resides in steel as a form of interstitial solid-solution. For nitriding at higher temperatures, nitride precipitates (gamma'-Fe_4N and zeta'-Fe_2N) exist mostly in grain boundaries and partly in grains of the steel. The nitrate nitriding gives rise to much larger nitriding depth than other nitriding methods at similar nitriding temperature and time. The nitrate nitriding of steel substantially increase its tensile strength as well as hardness, e.g., an IF steel specimen nitrided at 650 deg C for 1.5 h shows a tensile strength of 916 MPa, which is 2.2 times higher than that of non-nitrided IF steel specimen, and an elongation of 20 percent at 70 deg C. Severe serrations are observed in flow curves of nitrided steel specimens, mainly due to dynamic strain aging that occurs because of interaction between dissolved nitrogen and moving dislocations. The effective diffusion coefficient of nitrogen D_N obtained from the nitriding data, D_N = D_oexp(-Q/RT) with D_0=3.789 X 10~(-7)m~2 centre dot s~(-1) and Q = 76.62 kJ mol~(-1), is approximately the same as that for diffusion of nitrogen in alpha-iron.
机译：已经进行了在温度为400到650摄氏度的硝酸钾盐浴中对无间隙（IF）钢进行氮化的研究。盐会分解产生氮和氧。氮扩散到钢中，或钢被氮化，而氧在钢表面反应形成氧化皮。氧化皮厚度远小于氮化厚度。大部分氮以间隙固溶体形式存在于钢中。为了在更高的温度下进行氮化，氮化物沉淀（γ'-Fe_4N和zeta'-Fe_2N）主要存在于晶界中，部分存在于钢的晶粒中。在类似的氮化温度和时间下，与其他氮化方法相比，硝酸盐氮化产生的氮化深度要大得多。钢的硝酸盐渗氮大大提高了其抗拉强度和硬度，例如，在650℃下氮化1.5小时的IF钢试样显示出916 MPa的拉伸强度，这是非氮化IF钢的2.2倍试样，在70℃时的伸长率为20％。在渗氮钢试样的流动曲线中观察到严重的锯齿，这主要归因于由于溶解氮与移动位错之间的相互作用而产生的动态应变时效。从氮化数据获得的氮的有效扩散系数D_N，D_N = D_oexp（-Q / RT），D_0 = 3.789 X 10〜（-7）m〜2中心点s〜（-1），Q = 76.62 kJ mol 〜（-1）与氮在α-铁中的扩散近似相同。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号