论文部分内容阅读
铬钼钒珠光体耐热钢适于制造燃气轮机的焊接转子，这类鋼含合金成份少而机械性 能优良，但可焊性不良，因此，需要作焊接的研究。 本文认为产生冷裂缝的主要原因是由于焊接予热温度过低，焊道及其热影响区冷却 过快，奥氏体分解温度过低，转变成硬度高而塑性差的针叶状贝茵体，因此在刚性大的 不利条件下产生了冷裂。 焊接热裂缝是由于焊接规范不当，致使焊缝成形系数过小，一次结晶状态不利，焊 缝中心区杂质明显地聚集，因而降低了该灶的工艺强度而产生的。 本文分析了焊缝火口工艺条件不利是产生火口裂缝的重要原因，提出了填满火口， 大幅度减小焊接电流的措施，证实这些措施能有效地防止火口裂缝。 焊接铬钼钒珠光体耐热钢的重要关键之一是严格控制焊接予热温度。予热温度提高 可以防止冷裂，改善焊缝塑性，但相应降低其硬度和强度。本文提出了合理的予热温度 为 ３７０—４２０℃。 本文认不铬钼钒珠光体耐热钢虽然可焊性不良，但只要正确采用焊接材料，予热温 度、焊接规范及随后热处理工艺，是可以获得综合机械性能优良和没有工艺缺陷的焊接 接头。
Chromium molybdenum-vanadium pearlite heat-resistant steels are suitable for the manufacture of welded rotors for gas turbines. These steels contain a low alloy content but excellent mechanical properties but poor solderability and therefore require studies on welding. This paper believes that the main reason for the cold crack is that the welding preheating temperature is too low, the weld bead and its heat-affected zone are cooled too fast, the austenite decomposition temperature is too low, the hardness is changed and the poor plasticity coniferous bainite , So in the rigid adverse conditions have produced cold cracking. Weld hot cracks is due to improper welding specifications, resulting in the weld forming coefficient is too small, a negative crystallization state, the central part of the weld significant accumulation of impurities, thereby reducing the intensity of the stove and the resulting technology. In this paper, the unfavorable conditions of welding seam crater are the important reasons for cracking of crater. The measures to fill the crater and reduce the welding current are proposed. These measures prove that these measures can effectively prevent the cracking of the crater. Welding chrome molybdenum vanadium pearlite heat-resistant steel is one of the key to strictly control the welding temperature to the heat. Preheating temperature can prevent cold cracking, improve weld plasticity, but the corresponding reduction in hardness and strength. This paper presents a reasonable preheating temperature of 370-420 ℃. This article does not recognize chromium molybdenum vanadium pearlitic heat resistant steel weldability although poor, but as long as the correct use of the welding material, the temperature of the preheating, welding and subsequent heat treatment process specification, is excellent in mechanical properties can be obtained without process defects and weld joint.