The effect of heat treatment on the mechanical properties of a low carbon steel (0.1%) for offshore structural application

Abstract

In this study, a low carbon cast steel (0.1% C) alloy designed for offshore structures, and the mechanical properties of the alloy under different heat treatment cycles have been evaluated. The effect of austenitizing time on the austenite grain size was studied. Subsequently, the quenched samples with minimum austenite grain size subjected to tempering experiments at different tempering temperatures (450 °C, 550 °C, and 650 °C) and cooling rates (0.23, 36, and 50 °C/s) from the temperature. The results showed that by increasing the austenitizing time, the austenite grain size initially decreased and reached the minimum value with ASTM number of 6.35 and then followed by an increase. When the tempering temperature increased, yield and tensile strengths decreased, whereas the ductility properties improved. In addition, yield and tensile strengths were not affected by cooling rate from tempering temperature, whereas the ductility properties were slightly affected. The increase in tempering temperature significantly led to improvement in the toughness to fracture of the alloy. The effect of cooling rate on impact energy for the samples tempered at 450 °C and 550 °C was negligible. By the contrast, impact energy for the samples tempered at 650 °C was markedly affected by cooling rate, in which the highest value was achieved for a cooling rate of 50 °C/s.

Avaliação de Juntas Soldadas de um Aço Fundido de Alta Resistência para a Indústria Offshore

“…O objetivo do presente trabalho é analisar as propriedades mecânicas das juntas soldadas de um aço fundido de alta resistência e sua adequação para utilização em componentes de ancoragem, considerando que em algumas ocasiões esta é a solução recomendada para a fabricação de componentes. A este respeito, embora existam muitos estudos envolvendo o desenvolvimento de aços fundidos para várias aplicações [9,10,[12][13][14][15][16][17][18][19][66][67][68][69][70][71], informações sobre a relação entre propriedades mecânicas e microestruturais das juntas soldadas de aços fundidos para fins estruturais aços ainda são limitadas.…”

Microstructural Design and Mechanical Enhancement of δ-TRIP Steel Through Mo Micro-alloying and Isothermal Bainitic Transformation

“…23,25,32 The distinction between δ-ferrite and α-ferrite might be made by classifying them as follows: α-ferrite was the product of the transformation of austenite by the ICA stage, whereas δ-ferrite originates from solidification and survives through the hot deformation. 45,46 The austenite phase was transformed into the bainitic ferrite phase following heat treatment at IBT temperature. It was clear that the sheaf structure of A/M in secondary phases changed to a blocky structure, and the quantity of sheaf bainite rose as Mo-alloy was introduced to samples of TR-2Mo-2t and TR-2Mo-10t.…”

“…As a result, the IBT process resulted in a stronger and more carbon-rich lath austenite phase. 41,46 Lath austenite is created by subjecting the TR-1Mo sample to an IBT heat treatment at 450 °C for 2 and 10 min (Figure . 7.a and b). The majority of the austenite morphology in samples TR-2Mo-2t and TR-2Mo-10t in Figure . 7.c and d seemed to be blocky in contrast to samples TR-1Mo-2t and TR-1Mo-10t in Figure . 7.a and b, which might be due to the influence of Mo-alloy addition on the austenite morphology.…”

Evaluation of High Strength Cast Steel Welded Joints Suitable to Mooring Components

“…To simplify the manufacturing cycle, cast steel parts can become an interesting alternative because a reduction in the production cost of the order of 30% can be reached [13], encouraging researchers to focus on cast steels [19,20]. Although information regarding carbon content and heat treatment procedures remain still limited for selecting casting steels that are suitable for offshore structures, these steels are extensively used in the naval and offshore industry [13,[21][22][23][24] in the manufacturing of industrial parts earlier produced by expensive manufacturing processes, such as extrusion or forging and other complex thermo-mechanical processes [13]. When comparing high strength cast steels applied in mooring components manufactured by different routes (Table 2), the advantages of cast steels can be noted, because these steels present lower carbon and carbon equivalent contents in comparison to the forged steel widely used in the offshore industry, such as DIN 34CrNiMo6 [17], AISI 4130 [25,33] and AISI 8630 [26].…”