Recommendations for Improved Welding Procedures for Thick Steel Plates Through Thermo-Mechanical Analysis

Abstract

Welding of steel plates is accompanied by residual stresses that increase as the constraint provided by the welded components becomes greater. Consequently, crack initiation has been reported after welding thick plates due to the high residual stresses developed by the welding procedure. This is further exacerbated by the higher likelihood of imperfections present in thick steel plates due to the rolling and cooling process. The research described herein aims to develop improved submerged arc welding (SAW) procedures to reduce the residual stresses for steel plates of thickness greater than 50mm. Acceptance criteria are developed for discontinuities present in the steel plates prior to welding, to limit the probability of crack initiation. A parametric study of SAW procedure parameters was conducted utilizing a validated finite element model. Two welding procedures were recommended for thick steel plates. Discontinuity acceptance limits were also recommended for each welding procedure using a fracture toughness database and an expression developed to calculate the probability of a crack to initiate.Keywords: Thick steel plates -Welding procedure -Welding simulation -Discontinuities acceptance criteria This paper appears online as: Ibrahim, O., Lignos, D.G., Rogers, C.A. (2018). "Recommendations for Improved Welding Procedures for Thick Steel Plates through Thermo-Mechanical Analysis", International Journal of Steel Structures, pp. 1-20, DOI: https://doi.org/10.1007/s13296-018-0110-2 (in press). 3 IntroductionIn recent years, more stringent requirements have been employed for the design of steel infrastructure due to seismic and blast loading as well as the design complexity. For this reason, steel plates with thickness 50mm and higher are becoming common in the steel construction industry to form heavy built-up sections. Connecting such components through welding is an essential part of construction; for example, the welding of built-up members composed of thick steel plates and splice connections. Welding thick plates employs higher heat input than that required for commonly used 25mm plates. Additionally, the plate thickness provides substantial constraint to the contraction of the heated steel resulting in high post-welding tensile residual stresses that can lead to crack initiation (Blodgett & Miller, 1993;Fisher & Pense, 1987). Miller According to AWS D1.1 (2010) " Table 3.2"; the required prequalified minimum preheat and interpass temperatures for the welding of steel plates increase according to the plate thickness.However, AWS D1.1 (2010) also states in "Tables 4.2 and 4.3" that in order to qualify a welding procedure for unlimited thickness, it is permissible to use test plates of 25mm in thickness.Consequently, steel fabricators are using welding procedures qualified for thick plates that were This paper contains a proposal for an improved submerged arc welding (SAW) procedure for thick plates using a partial penetration butt joint. This was achieved based on a rigorous parametric study that in...