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对不同Ti含量的气电立焊焊缝组织及力学性能进行了对比研究。结果表明,Ti的质量分数在0.028%~0.038%范围内时,焊缝中获得大量细小的针状铁素体,焊缝组织及低温韧性得以明显改善。当Ti过量时,焊缝中的针状铁素体减少,组织以贝氏体为主,低温韧性相应下降。焊缝组织中观察到块状和条状的M-A组元,随着焊缝Ti含量增加,其总量增加。焊缝夹杂物多为以氧化物为核心,外层包裹着MnS的复合夹杂物,并随夹杂物Ti含量的增加,由Mn-Si-Al-O型向Ti-Mn-Al-O型转变,有利于促进针状铁素体形成。而当焊缝中Ti过量时,主要夹杂物又转变为对针状铁素体形核无效的Ti-Al-O型,促进了贝氏体转变。
A comparative study on microstructure and mechanical properties of gas-electric vertical weld with different content of Ti was carried out. The results show that when the mass fraction of Ti is in the range of 0.028% -0.038%, a large amount of fine acicular ferrite is obtained in the weld, and the microstructure and low temperature toughness of the weld joint are obviously improved. When Ti is excessive, the amount of acicular ferrite in the weld decreases, the microstructure is dominated by bainite and the low temperature toughness decreases accordingly. The massive and strip M-A components were observed in the weld seam, and the total amount increased with the increase of Ti content in the weld. The weld inclusions are mostly complex inclusions with oxide as core and outer cladding as MnS. With the increase of Ti content of inclusions, the transition from Mn-Si-Al-O type to Ti-Mn-Al-O type , Is conducive to promoting acicular ferrite formation. However, when Ti is excessively contained in the weld, the main inclusions turn into Ti-Al-O type, which is not effective for acicular ferrite nucleation and promote the transformation of bainite.