不只直接在低温下焊接的焊件,就是在常温下焊成的結構,而在低温下使用,低溫对它們裂縫的形成都有很大的影响。有些焊件或結構在低温下产生的裂縫是相当严重的。这种情况的发生,首先是由于鋼材在低温下的冲击靭性急剧降低。图1表示低碳鋼(3号鋼)的冲击靭性随着温度而变化的情况。同样,焊接接头的冲击靭性也因温度降低而下降,因而也增加了出現裂縫的可能性。 Not only the welding directly welded at low temperature is the structure welded at room temperature, but at low temperature, low temperature cracks have a great impact on their formation. Some welds or structures produce cracks at low temperatures that are quite severe. This happens, first of all, due to the steep reduction of the impact toughness of the steel at low temperatures. Figure 1 shows the impact toughness of mild steel (steel # 3) as a function of temperature. Similarly, the impact toughness of welded joints is also reduced by the temperature decrease, thus increasing the possibility of cracks.