Stimulated material-environment interactions inside and around flowlines of deep or ultra deep wells during oil and gas exploration, and fabrication economy of pipelines have been the major challenges facing the oil and gas industries. Presumably, an extensive focus on high integrity, performance and material economy of flowlines have realistically made supermartensitic stainless steels (SMSS) efficient and effective material choices for fabricating onshore and offshore pipelines. Supermartensitic stainless steels exhibit high strength, good low temperature toughness, sufficient corrosion resistance in sweet and mildly sour environments, and good quality weldability with both conventional welding processes and modern welding methods such as laser beam welding, electron beam welding and hybrid welding approaches. In terms of economy, supermartensitic stainless steels are cheaper and they are major replacements for more expensive duplex stainless steels required for tubing applications in the oil and gas industry. However, weld areas of SMSS pipes are exposed to sulphide stress cracking (SSC), so intergranular stress corrosion cracking (IGSCC) or stress corrosion cracking can occur. In order to circumvent this risk of cracking, a post-weld heat treatment (PWHT) for 5 minutes at about 650 °C is recommended. This paper provides detailed literature perusal on supermartensitic stainless steels, their weldability and corrosion behaviors. It also highlights a major research area that has not been thoroughly expounded in literature; fatigue loading behaviors of welded SMSS under different corrosive environments have not been thoroughly detailed in literature.

Structural damage and fatigue life of engineering materials are controlled by inherent defects and the nature, level, and location of applied external loads. This paper studies the effect of cyclic lateral loads on the pinless and conical-pin assisted friction stir spot welds of AA2219 alloy. The results reveal the presence of upward-flow induced hook defect and outstretchingflow induced microscopic toe-notch in the conical pin and pinless welds, respectively. Extruded flash root contributed to the fracture pattern of the conical pin welds while it did not influence the fracture of the pinless weld. Grain refinement, microhardness, and microscopic toe-notch affect the fracture mode of pinless weld whereas complex fracture morphology ensues in conical pin weld. A decrease in the cyclic lateral stress level improves the lateral fatigue lives of both weld categories. Lateral fatigue improvement of welds requires the minimization of inherent nugget defects and extruded flash.

This paper examines the effects of inoculant type and treatment material quantity on the mechanical and thermal properties of rail vehicle brake discs manufactured from vermicular graphite cast iron/compacted graphite iron (CGI). The in-mold treatment technique was employed in manufacturing the CGI brake discs. The main and interaction effects of inoculant type and treatment material quantity parameters affecting the tensile strength of the CGI brake discs were determined. The results indicate that treatment material quantity has the most significant effect on mechanical properties. Tensile strength was observed to increase as the treatment material quantity increased. The optimum level for manufacturing the CGI brake disc by using the in-mold treatment technique was attained via the combination of SB 5-type inoculant and 625 g treatment material quantity.