高强度钢材Q690和Q960的焊接拼接短柱轴压试验研究

Experimental Investigation into the Axial Compression of Welded Stocky Columns of Q690 and Q960 High Strength Steel

近年来,随着冶金技术的发展,屈服强度在460 MPa及以上的高强度钢材和超高强度钢材已在我国实现了工业化生产。这类钢材采用热处理工序获得特定的微观结构,优化其材料属性和机械特性,在建筑结构的受力性能、经济效益和节能减排等方面都具有突出的优点。然而,一些研究人员指出,由于冶炼过程中必须的热处理工序,这些高强钢的微观结构在焊接过程中很容易受到影响,发生金属相变,导致焊接热影响区的各种机械性能降低。因此,有必要对建筑工业实用尺寸(如10~30 mm厚)的高强钢Q690和Q960板焊接后结构表现进行深入的研究和量化评估。针对这一问题,首先对Q690和Q960钢材10~30 mm厚的母材试件进行了单调拉伸试验,获得其机械性能。同时,对高强钢Q960在熔化极气体保护电弧焊不同焊接热输入下的焊接接头进行了单调拉伸试验,研究焊接热输入对其屈服强度、抗拉强度、延伸率等的影响,并依据相关试验数据开发了针对Q690和Q960中厚板特定热输入的焊接工艺规范。之后,采用此焊接工艺规范进行加工,并在香港理工大学结构工程实验室对共计36个不同对接拼接焊热输入、不同截面分类的Q690和Q960焊接拼接短柱开展了全面的轴压试验研究,量化了在不同焊接热输入下的高强钢Q690和Q960焊接拼接短柱在轴向压缩下的截面承载力,并将试验结果与现行欧盟规范EN 1993-1-1中的设计要求进行了比较。最后,分析了现行欧盟规范EN 1993-1-1中对于截面分类的规定在高强钢Q690和Q960短柱焊接工字形截面和箱形截面上的适用性,提供试验数据,提出了对现有截面分类规定的一些意见。

With the development of metallurgical technology,high-strength steel and ultra-high-strength steel with yield strengths of 460 MPa and above have been industrially produced in China,with production increasing year by year.These steels use heat treatment processes to obtain specific microstructural compositions,optimize their material properties and mechanical characteristics,and have outstanding advantages in terms of the stress performance of building structures,economic benefits and energy saving and emission reduction.However,some researchers believe that the microstructures of these high-strength steels are easily affected during the welding process due to the heat treatment process during smelting,resulting in the reduction of various mechanical properties in the weld heat-affected zone.Therefore,there is a great need to study and quantify this post-welding structural behaviour of high-strength Q690 and Q960 steel plates in practical sizes for the construction industry(e.g.10 to 30 mm thickness).To address this issue,welding process specifications for Q690 and Q960 medium thickness plates were developed,and a comprehensive experimental study was carried out on a total of 36 short columns of high-strength steel to quantify the cross-sectional load carrying capacity of welded spliced short columns of high-strength steels Q690 and Q960 under axial compression with different welding heat inputs,and to analyse,in comparison with the design requirements of the current European Union norm EN 1993-1-1,that the applicability of the existing codes on short columns of high strength steel and ultra-high strength steel is also analyzed,experimental data are povided,and some opinions on the regulations of exising section classification are proposed.