地质钻杆镦头过程中产生裂纹的原因分析与解决方法

钻杆在加工过程中需要对两头进行镦头加厚处理,但经处理后的钻杆头部在后续加工中成批出现裂纹.通过对钻杆材质采用化学成分分析、光学显微镜金相组织检查以及力学性能测试等方法,对出现裂纹的部位进行了分析.结果表明,材料原始组织铁素体和珠光体呈带状分布,导致材料出现各向异性.在镦头过程中,应力在镦头变径处造成集中,超过了材料的抗弯极限,导致其发生脆性开裂,从而出现裂纹.经试验,合理选择加热速度和冷却时间,可以减缓材料带状组织的影响,降低镦头部位出现裂纹.

In the process of geological drill pipe heading head crack causal analysis and resolution method

In the process of drill pipe ends are heading to thickening treatment,but after treatment,the drill head during subsequent processing to crack.Through the drill pipe material by chemical composition analysis,optical microscope metallographic examination and mechanical property testing,to crack location are analyzed.The results show that,original microstructure of ferrite and pearlite with zonal distribution,cause material anisotropy.In the upsetting process,stress in the head diameter caused concentration,more than the bending limit,leading to its brittle cracking,thus appears the crack.Through the test,a reasonable choice of heating rate and cooling time,can slow down the material the effect of banded structure,lower head parts crack.