Characterization of the austemperability of partially austenitized ductile iron

This study focuses on the characterization of the hardenability and the austemperability of partially austenitized ductile iron melts alloyed with small amounts of Cu, Ni and Mn.     

厚大件用低合金耐磨钢的研制

针对厚断面、大截面耐磨件研究了一种新型低合金耐磨钢,对其化学成分、组织性能和热处理工艺进行了探讨.结果表明:这种新型低合金耐磨钢有足够的淬透性,热处理后的组织为马氏体或马氏体/下贝氏体的复相组织;材料具有较高的强韧性,其硬度＞48 HRC,冲击韧度αk可达49 J/cm2以上,伸长率δ＞6%,抗拉强度σb＞1 350 MPa;材料的耐磨性是普通高锰钢的1.36倍以上;这种低合金耐磨钢的合金加入量较少,成本低廉,易于推广和应用,具有明显的经济与社会效益.     

硅锰合金化奥贝球铁的热处理工艺研究

研究了水 油双液淬火→等温回火的连续冷却热处理工艺对铸件力学性能、残余奥氏体含量、淬透性以及贝氏体组织形貌的影响。实验结果表明:贝氏体首先以细针状从石墨-基体边缘析出,最终基体组织为大量贝氏体和少量残余奥氏体;随着等温回火温度的升高,铸件的bσ降低,αk升高,硬度先降低后升高,残余奥氏体含量先升高后降低,在380℃,铸件硬度最低,残余奥氏体含量最高;淬透性与等温回火温度无关。     

一种粉末冶金零件的热处理工艺性能分析与研究

通过对某粉末冶金零件工作环境及其工作特点分析,确定零件材料,并对其所选粉末冶金材料的热处理方法即淬火的温度、保温时间、冷却方式及回火工艺等做出了相应的分析.通过对零件热处理前后的性能对比分析,得出铁基粉末冶金零件整体淬火时,孔隙度与合金含量对其淬透性的影响.     

FAS3550少片变截面板簧钢的研制

对FAS3550少片变截面板簧钢研制生产工艺进行介绍，论述了冶炼及轧制生产工艺特点，提出了提高弹簧钢纯净度、强韧性及降低脱碳层的工艺措施，最后将研制产品与瑞典进口板簧材料冶金质量对比，得出新材料力学性能优于进口材料的结论。     

Hardenability testing of steels when gas quenching is applied

Abstract

The common test for assessing hardenability is the standardised Jominy end-quench test according to ASTM-A255 or DIN-EN 50191. This test is applied essentially for non-alloyed and low alloyed structural steels, when quenched in liquid quenchants, but it is not applicable for high alloyed (air hardening) steels, because the cooling rate at the opposite end of the Jominy specimen is higher than the critical cooling rate of those steels. Today there is no a standardised method to test and evaluate the hardenability of high alloyed steels. Nowadays, not only high alloyed steels, but also some low alloyed structural steels are quenched by high pressure gas quenching (HPGQ) in vacuum furnaces. Obviously there is need from one side to develop a standardised method for testing and evaluation of hardenability for high alloyed steels when they are gas quenched, and from the other side to establish a database for hardenability of low-alloyed structural steels when they are quenched in vacuum furnaces by HPGQ, i.e. at different high pressures and different flow velocities. Corresponding equipment that can be used to satisfy both requirements is discussed.     

Microstructural characterisation of nickel rich areas and their influence on endurance limit of sintered steel

Abstract

Nickel is an often used alloying element in powder metal steel to achieve high hardenability. However, when nickel is added, the slow diffusion rate between iron and nickel leads to the formation of nickel rich areas (NRAs). Two steel alloys were studied: a Fe–6·4Ni–0·7Mo–0·7C with standard sized nickel powder additions and a Fe–2·4Ni–0·7Mo–0·7C with a finer sized nickel powder. Microstructural characterisation of the parts revealed that sufficient hardenability was achieved for both materials, but that NRAs were observed when standard sized nickel is used. X-ray energy dispersive spectrometry and electron diffraction show that the NRAs are composed of martensite and austenite under rapid cooling conditions. Three-point bending fatigue tests were carried out on both alloys to evaluate the effect of these soft austenitic areas on the fatigue properties of powder metal steel parts. The analysis of the endurance limit results shows that NRAs are not a governing factor.     

淬透性预测在热处理CAD系统中的应用

讨论了有关计算端淬曲线，等效端淬距离，回火硬度－回火温度和计算机辅助选材二维逻辑表的数学模型在热处理ＣＡＤ中的应用，并介绍了在软件工程思想指导下开发的“淬透性预测和计算机辅助选材系统”的功能特性。     

人工神经网络模型预报汽车齿轮钢淬透性

采用人工神经网络模型预测汽车齿轮钢淬透性的精度 (相对误差± 6 % )高于线性回归分析预测的精度 (相对误差± 10 % ) ,它是一种容错性好 ,通用性强的可靠的淬透性预报方法。     

铜对高硼铁基合金性能的影响

高硼铁基合金中由于硼的存在,加入的锰、铬等用来增加淬透性的元素大部分形成了硼化物,影响了材料的淬透性。而且由于高硼铁基合金中的硼化物导热性能不好,也会影响到材料的淬透性。本文通过添加铜来研究其提高材料淬透性的效果。铜在钢中的作用与镍类似,可以提高钢的淬透性,含量适当时可以提高钢的冲击韧度。在硼钢中,铜的加入可以提高硼在钢中的溶解度,从而可以改善硼钢晶间硼化物的形态,提高钢的力学性能。在高硼铁基合金中,铜不与硼反应,而且不溶于硼化物中,可以充分发挥其增加淬透性的作用。实验结果表明,铜可以有效的增加高硼铁基合金的淬透性,并且可以提高其冲击韧度。