论文部分内容阅读
对50毫米(2英寸)厚HY-130钢板采用GMAW(气体保护金属极电弧焊)焊接工艺制作了一种测试用的焊缝。在从熔融面右侧到距熔融面25毫米(1英寸)的若干位置处记录了整个多道焊接的热过程。用显微硬度的横向分布测定,光学显微镜检验和碳萃取复型及薄膜的透射电子显微镜检验来表征该焊件不同位置所经历的不同热过程的效应。硬度横向分布测量结果表明,由于多道焊缝中发生的热循环,热影响区(HAZ)的硬度能降低60HV,但在大多数情况下,仅降低30HV。热影响区由两个硬度明显不同的区域组成。最硬的区域靠近母材,最软的区域靠近熔融面。金相检验表明,上述情况是由于这些位置的显微组织不同。在整个“硬”区域存在着细条状马氏体,在“软”区域则是粗条状贝氏体和细条状马氏体的混合物占支配地位。粗条状贝氏体还包含少量孪晶马氏体。上述观测结果与具体热过程有关,本文参照由这些显微组织预期的断裂抗力对其进行了讨论。
A weld seam for testing was made on a 50 mm (2 inch) thick HY-130 steel using a GMAW (gas shielded metal arc welding) welding process. The thermal history of the entire multichannel soldering process was recorded at several locations 25 mm (1 in.) From the right side of the fusible surface to the fusible surface. The effect of different thermal processes experienced at different locations on the weldment was characterized by transverse distribution measurements of microhardness, optical microscopy and carbon extraction reticle and transmission electron microscopy of the film. The results of the lateral distribution of hardness show that the hardness of the heat affected zone (HAZ) can be reduced by 60HV due to the thermal cycling occurring in the multiple passes, but only 30HV in most cases. The HAZ consists of two distinctly different areas of hardness. The hardest area is near the base metal and the softest area is near the melting surface. Metallographic examination showed that the above situation is due to the different microstructures at these locations. Sliver-like martensite is present throughout the “hard” region, whereas the “soft” region is dominated by a mixture of coarse-bainitic and lath martensite. Rough bainite also contains a small amount of twinned martensite. The above observations relate to specific thermal processes, which are discussed in this paper with reference to the expected fracture resistance of these microstructures.