悬索桥用大直径螺杆的生产工艺

悬索桥主缆采用AS法架设时,其锚固螺杆将承受较大的股靴拉应力作用。为保证锚固系统的安全,一般可通过增大螺杆直径来提高其承载力。但大直径螺杆制造难度较大,且缺乏成熟的制造工艺。为确定合理的大直径螺杆制造工艺,以阳宝山大桥150 mm的大直径螺杆为例,讨论了悬索桥用大直径螺杆制造工艺。螺杆选材为淬透性能良好的40CrNiMoA钢,分别采用锻造和热轧两种成型方式制备,后采用880 ℃油淬、860 ℃水淬+油冷2种热处理方式处理得到共4组试件,并对试件进行力学性能测试。试验结果表明,热轧和锻造成型后880 ℃油淬处理的2组试件,其综合力学性能不满足产品标准GB/T 3098.1—2010 10.9级要求;热轧和锻造成型后860 ℃水淬+油冷处理的2组试件,其综合力学性能满足产品标准GB/T 3098.1—2010 10.9级要求,抗拉强度不小于 1 040 MPa,规定非比例延伸0.2%的应力不小于940 MPa,-20 ℃吸收能量不小于27 J,且显微组织优良。两种材料成型方式中热轧经济性更好。最终确定大直径螺杆合理的制造工艺为热轧成型、860 ℃水淬+油冷热处理。

Production technology of large diameter screw for suspension bridge

When the suspension bridge main cable is installed by AS method, the anchor screw will bear tensile stress of thigh shoe. In order to ensure the safety of Anchorage System, the bearing capacity can be increased by increasing the diameter of screw. But the manufacture of large diameter screw is more difficult, and lack of sophisticated manufacturing techniques. In order to determine the reasonable manufacturing technology of large diameter screw, supported by a large diameter screw with a diameter of 150 mm in Yangbaoshan Bridge, the manufacturing technology of large diameter screw for suspension bridge was studied. 40CrNiMoA steel with good hardenability was selected, which was prepared by forging and hot rolling respectively. Four groups of specimens were produced by pure oil quenching at 880 ℃ and water quenching at 860 ℃ + oil cooling, and the mechanical properties of these specimens were tested. The results showed that,the comprehensive mechanical properties of hot-rolled and forged specimens quenched by pure oil at 880 ℃, not met the requirements of product standard GB/T 3098.1—2010 10.9. The comprehensive mechanical properties of hot-rolled and forged specimens heat-treated by water quenching at 860 ℃ and oil cooling, met the requirements of product standard GB/T 3098.1—2010 10.9, R_m≥1 040 MPa,Rp0.2≥940 MPa,KV(-20 ℃)≥27 J,and microstructure was good. In addition, the hot rolling has better economy in the two material forming methods, therefore, it is decided to adopt the hot-rolling forming method and the heat treatment method of water quenching + oil cooling at 860 ℃ as the reasonable manufacturing process of the large diameter screw.