Q460高强度钢冷挤压内螺纹表层的组织结构及耐腐蚀性能

Microstructure and Corrosion Resistance Properties of Internal Thread During Cold Extrusion for Q460 High Strength Steel

根据冷挤压内螺纹的成形过程,研究冷挤压内螺纹的表层组织结构,并从腐蚀后冷挤压内螺纹表层状况发生变化的角度来研究其耐腐蚀性能。结果表明,冷挤压内螺纹表层晶粒被破碎和细化到难以分辨出晶粒的程度,金属组织呈流线型沿牙面法相分布。冷挤压内螺纹表面硬化层对腐蚀能够产生抑制作用,在相同腐蚀环境下冷挤压内螺纹表面硬化层可减轻试样表面的腐蚀破坏程度,使其不易形成腐蚀坑而造成局部应力集中,具有较好的疲劳性能。

According to the forming process of cold-extruded internal thread,the microstructure at the surface of cold-extruded internal thread was investigated.The corrosion resistance was analyzed from the changing perspective of surface status of cold-extruded internal thread.The results showed that the fibrous structure of the metal surfaces on the root of thread was pressed and refined to distinguish the grains difficultly.The metal structure appeared to be streamline type and distributed along the normal direction of the tooth surface.The hardening layers of cold-extruded internal thread had an adverse effect on corrosion,and it reduced corrosion degree at the surface of the sample in the same corrosive environment,and mostly avoided producing corrosion pits to cause local stress concentration.Cold-extruded internal thread had better corrosion resistance.