Effect of Tempering Temperature on Microstructure and Sulfide Stress Cracking of 125 Ksi Grade Casing Steel

Abstract

The influence of tempering temperature on the microstructure of 0.5Cr0.4W steels was investigated by scanning electron microscope, and the roles of grain boundary character, dislocation, and Taylor factor in sulfide stress cracking (SSC) resistance were interpreted using the election backscattered diffraction technique. The 0.5Cr0.4W steels tempered at 690 °C, 700 °C, and 715 °C all showed tempered martensites. The specimen tempered at 715 °C exhibited a higher critical stress intensity factor (KISSC) of 34.58 MPa·m0.5, but the yield strength of 800 MPa did not meet the criterion of 125 ksi (862 MPa) grade. When the specimen was tempered at 690 °C, the yield strength reached 960 MPa and the KISSC was only 21.36 MPa·m0.5, displaying poorer SSC resistance. The 0.5Cr0.4W steel tempered at 700 °C showed a good combination of yield strength (887 MPa) and SSC resistance (KISSC: 31.16 MPa·m0.5). When increasing the tempering temperature, the local average misorientation and Taylor factor of the 0.5Cr0.4W steels were decreased. The reduced dislocation density, and greater number of grains amenable to slippage, produced less hydrogen transport and a lower crack sensitivity. The SSC resistance was, thus, increased, owing to the minor damage to hydrogen aggregation. Therefore, 700 °C is a suitable tempering temperature for 0.5Cr0.4W casing steel.

Simultaneous Enhancement of Strength and Sulfide Stress Cracking Resistance of Hot-Rolled Pressure Vessel Steel Q345 via a Quenching and Tempering Treatment

“…The usual viewpoint on the SSC of steel is that hydrogen penetration can happen under the condition of the release of hydrogen. It is well known that the SSC mechanism is attributed to the susceptibility of the hydrogen embrittlement (HE) [24][25][26][27][28][29], which could also be substantiated by the evidence revealed in the present work shown in Figure 4, where Figure 4a shows blisters of hydrogen on the outside surface in the cracked specimen, Figure 4b shows secondary cracks on the fracture surface in a cracked specimen, and Figure 4c shows the predominant quasi-cleavage characteristic on the fracture surface in a cracked specimen. Therefore, the SSC failure of the present experimental steel agreed with the hypothesis on the embrittling contribution by hydrogen, i.e., decided by the hydrogen permeation-controlled mechanism [24][25][26][27][28][29].…”

Perancangan Metode Machine Learning Berbasis Web Untuk Prediksi Sifat Mekanik Aluminium

“…Perkembangan teknologi komputer yang begitu pesat di bidang ilmu material mendorong para ahli dan peneliti dalam mengembangkan pendekatan komputasi dalam menganalisa dan memecahkan berbagai permasalahan dibidang material [6] . Metode machine learning (ML) merupakan salah satu metode yang praktis untuk membangun korelasi antara data dan menyelesaikan permasalahan dibidang ilmu material yang kompleks dan non linear [7] , hal ini dapat dilihat pada web of science yang menyatakan bahwa hampir 2000 makalah diterbitkan tentang topik ini pada tahun 2020 saja, dibandingkan dengan hanya sekitar 400 makalah pada tahun 2017 [8] .…”