Cuilan WU
,
Chengping LUO
,
Ganfeng ZOU
材料科学技术（英文）
Low temperature composite chromizing is a process composed of a plain ion-carbonitriding or ion-nitriding at 550~580℃, followed by a low-temperature chromizing in a salt-bath of 590℃. The microstructure and properties of the low temperature composite chromized layer on H13 tool steel were investigated using metallography, X-ray diffraction, microanalysis, hardness and wear tests. It was found that this low temperature process was thermodynamically and kinetically possible, and the composite chromized layer on H13 steel, with a thickness of 3~6 μm, consisted of three sub-layers (bands), viz. the outer Cr-rich one, the intermediate (black) one, and the inner, original white layer. After chromizing, the former diffusion layer was thickened. The results of X-ray diffraction showed that the composite chromized layer contained such nitrides and carbides of chromium as CrN, Cr2N, (Cr, Fe)23C6, and (Cr, Fe)7C3, as well as plain α-(Fe, Cr). A high surface microhardness of 1450~1550 HV0.025, which is much higher than that obtained by the conventional ion carbonitriding and ion nitriding, was obtained. In addition, an excellent wear resistance was gained on the composite chromized layer.
关键词:
H13 tool steel
,
null
,
null
张金祥
,
卢林
,
王和斌
,
黄进峰
,
崔华
,
张济山
材料导报
采用常规铸造和喷射成形工艺分别制备了H13钢,应用OM、SEM、XRD等方法研究了铸态、喷射沉积态及过喷粉的组织.采用LMS-30粒度仪对过喷粉进行了粒度分析.结果表明:铸态H13钢为粗大的枝晶组织,合金元素与碳化物偏析严重,而喷射成形H13钢为细小的等轴晶组织,几乎没有碳化物,含有较多的残余奥氏体.过喷粉是枝晶组织,随粉末尺寸的减小,一次枝晶变小,二次枝晶臂已不明显,是欠发达枝晶组织.雾化压力的增加对小颗粒过喷粉的尺寸和数量影响甚微,但会明显减小大颗粒过喷粉末的尺寸,并增加其数量.喷射成形等轴晶的形成机制在气液比偏小时以未破碎枝晶的均质化与碎断枝晶的连接长大为主,而在气液比偏高时以大量破碎枝晶作为异质形核核心为主.
关键词:
喷射成形
,
H13钢
,
微观组织
,
过喷粉末
郝勇飞
,
成国光
,
谢有
材料热处理学报
对含铌0.051％的H13钢铸锭中一次碳氮化物成分特征及在1150℃、1250℃下的热稳定性进行了分析,并利用热力学软件Thermoo-Calc对其形成机制进行了合理的解释.研究发现含铌0.051％的H13钢铸锭中存在3类一次碳氮化物,富Nb类、富v类以及富Mo-Cr类相.富Nb相热稳定性高,在1150℃及1250℃下保温6h仍大量存在.富V相在1150℃下保温6h仍然存在,而在1250℃下保温6h即可完全固溶.富Mo-Cr相热稳定性低,无论是在1150℃还是1250℃下,均没有发现.这些相是在凝固过程中由于元素富集而在液相中析出.凝固过程中,富V的碳氮化物相首先析出,之后随着Nb含量的富集,富Nb的碳化物相开始析出,当Nb元素消耗到一定程度而同时V元素进一步富集后,富V的碳化物相再次析出,富Mo-Cr相在凝固末期最后析出.
关键词:
H13钢
,
Nb
,
热稳定性
,
生成机理
,
Thermo-Calc
