第1部分:A588 A级和A572 50级焊缝的断裂行为对ASTM A588 A级和ASTM A572 50级微合金钢与Linde 40B焊缝金属进行埋弧焊，以确定基板、焊缝金属和热影响区的断裂性能。研究中包括了板材取向、热处理、热输入和焊后热处理对热影响区韧性的影响。对焊缝金属和基板的拉伸性能进行了评估。 对焊接热影响区（HAZ）进行硬度测试。在一定温度范围内对板材、焊缝和热影响区进行夏比冲击试验。确定了板材和焊缝金属的零塑性转变温度。焊缝金属拉伸试验表明，Linde 40B焊缝金属的强度超过了基板。焊后热处理对这种焊接金属的强度或延展性影响最小。第2部分:长时间焊后热处理对结构钢性能的影响- 钢焊接件各种规范规则通常要求，根据焊接件的类型和厚度，对压力容器、核电厂支架和海上平台等焊接结构进行焊后热处理（PWHT）。在制造过程中，可对结构进行多次焊后热处理，在某些情况下，高温下的总时间可能接近100小时。因为在某些情况下，焊后热处理可能会导致母材、热影响区（HAZ）或焊缝金属的强度损失和韧性退化，焊后热处理后，焊件的机械性能可能不符合客户或规范的要求。

Part 1: The Fracture Behavior of A588 Grade A and A572 Grade 50 WeldmentsAn experimental study was conducted on ASTM A588 Grade A and ASTM A572 Grade 50 microalloyed steels submerged arc welded with Linde 40B weld metal to determine the fracture properties of base plates, weld metal and heat-affected zones. The effects of plate orientation, heat treatment, heat input, and postweld heat treatments on heat-affected zone toughness were included in the investigation. Tensile properties were evaluated for the weld metal and base plates. Hardness tests were done on weld heat-affected zones (HAZ). Charpy impact tests were performed over a temperature range for plates, welds and heat-affected zones. The nil-ductility transition temperature was determined for the plates and the weld metal.The weld metal tensile tests showed that the Linde 40B weld metal overmatched the baseplates in strength. Postweld heat treatment had minimal effect on either the strength or ductility of this weld metal.Part 2: Effects of Long-Time Postweld Heat Treatment on the Properties of Constructional-Steel WeldmentsVarious code rules often require that welded structures such as pressure vessels, nuclear-power-plant supports, and offshore platforms be postweld-heat-treated (PWHT), depending on type and thickness of the weldment. The PWHT may be performed several times on a structure during fabrication, and the total time at elevated temperature may approach 100 hr in some situations. Because PWHT may, in some instances, result in loss in strength and degradation in toughness of the base metal, heat-affected zone (HAZ), or weld metal, the mechanical properties of the weldment may not meet customer or code specifications after PWHT.