焊后热处理工艺对微合金钢焊缝组织与性能的影响.pdfVIP

焊后热处理工艺对微合金钢焊缝组织与性能的影响 魏世同 吕 冬 徐荣杰 刘仁东 （鞍钢股份技术中心汽车与家电用钢研究所，鞍山 114009 ） 摘要 采用含Nb 焊丝对 S355 钢板进行焊接，分析了焊后热处理制度对含Nb 微合金钢焊缝金属组织和性能的影响。 结果表明：经焊后去应力退火处理后，焊缝金属的强度升高，延伸率和冲击功降低，退火后焊缝金属中 NbC 颗粒 析出是影响焊缝金属性能的主要因素。在焊后正火处理条件下，随着正火温度的升高，焊缝金属中 NbC 颗粒的数 量减少，同时焊缝中魏氏组织的含量明显增多，导致焊缝金属的强度明显升高，伸长率和冲击功显著降低，因此对 于含 Nb 焊缝金属为得到较高的韧性，正火温度不能设定过高。当在 900℃进行多次正火处理时，随着正火次数的 增加，焊缝金属中 NbC 析出相的尺寸明显增大，经 3～4 次正火处理后，焊缝金属组织达到最细化。 关键词 热处理工艺 焊缝金属 微观组织 力学性能 Effects of Heat Treatments on the Microstructure and Properties of the Micro-alloyed Steel Weld Metal Wei Shitong Lv dong Xu rongjie Liu Rendong (Automobile and Home Appliance Steel Institute, Technology Center of Angang Steel Co., Ltd, Anshan ,114009) 1 Abstract S355steel plates were welded using a kind of Nb bearing welding wire. The effects of different post weld heat treatments on the microstructure and mechanical properties of the Nb bearing weld metal were analyzed systematically. Experimental results showed that after stress relief annealing, the strength of the Nb bearing weld metal increased, while the elongation and impact toughness decreased. NbC particles forming in the annealing process was a main factor influences the properties of weld metal. In the case of normalizing treatments for the weld metal, it was shown that with the increase of the normalizing temperature, the quantity of the NbC particles decreased, the content of widmanstatten ferrite increased, which induced the strength increased obviously and the elongation and impact toughness decreased significantly with the normalizing temperature increasing. Therefore, in order to get higher toughness for the Nb bearing weld metal, the normalizing