Mechanical Properties of Ultra High-Strength Steel Welded Joints

摘要

The objective of the study was to compare conventional welding methods and their suitability for high-strength steels as alternative choice for laser or laser-hybrid welding. The joining methods were metal-active gas welding (MAG), plasma arc welding (PAW) and submerged arc welding (SAW). Test welds were evaluated by metallography, tensile tests, impact tests, fatigue tests and hardness profiles. Also, the effects of residual stresses of base material on the welding distortion in butt-welded joints were studied. Test materials were ferritic-bainitic Optim 700 MC Plus and bainitic-martensitic Optim 900 QC steels. The studies showed that the conventional welding methods can produce high quality welds if the possibilities and limitations of each welding method are recognized, and single-pass butt welds can be produced up to material thickness of 8 mm. Mechanical properties of the weldments are controlled by the heat input, cooling time Δt_(8/5) and consumable