Abstract
Abstract High-temperature tensile tests at 25, 150, 250, and 350°C were carried out on 30CrMo, 42CrMo, 1Cr13, and 304 steels. The changes in tensile strength, yield strength, elongation, and area reduction ratio with temperature were determined. By analyzing the fracture morphology and the relationship between strength and hardness, the influence of high-temperature mechanical properties on crack sensitivity and the mechanism of crack formation is discussed. Experimental results indicated that both the tensile and yield strengths of the four steels gradually decrease with the increase in temperature. The yield ratios of 30CrMo, 42CrMo, 1Cr13, and 304 steels are, respectively, 0.71–0.77, 0.79–0.86, 0.84–0.88, and 0.33–0.40 which shows that among the four steels, 304 has the best ductility, while 1Cr13 has the worst ductility. As for the four steels, the values of reduction ratio of area are greater than 60%, except for 42CrMo which is slightly lower than 60% at 150 and 250°C, indicating that the four steels have low crack sensitivity within the test temperature range. Ductile fracture is the main fracture mechanism for 30CrMo, 42CrMo, and 304 steel, whereas brittle fracture is predominant for 1Cr13. There is a linear regression relationship between the strength and hardness at different temperatures. The obtained linear regression relationship can be used to predict and estimate the strength of 30CrMo, 42CrMo, 1Cr13, and 304 steels at different temperatures according to the hardness results.
Highlights
As the world’s most recognized effective method for heavy oil recovery, thermal recovery can further increase crude oil recovery and reverse the current situation of low recovery [1]
* Corresponding author: Shaodong Ju, Drilling & Production Engineering Research Institute, CNOOC EnerTech-Drilling & Production Co., Tianjin 300452, China, e-mail: jushd2@cnooc.com.cn Binqi Zhang: Engineering Department, CNOOC China Limited, Tianjin Branch, Tianjin 300459, China Chuangang Liu: Drilling & Production Engineering Research Institute, CNOOC EnerTech-Drilling & Production Co., Tianjin 300452, China Yingwen Ma: Engineering Operation Center, CNOOC China Limited, Tianjin Branch, Tianjin 300459, China Haiyan Chen: College of Ocean Science and Engineering, Shanghai Maritime University, Shanghai 201306, China Li Fan: College of Mechanical and Electronic Engineering, Shanghai Jian Qiao University, Shanghai 201306, China predict and estimate the strength of 30CrMo, 42CrMo, 1Cr13, and 304 steels at different temperatures according to the hardness results
As for the four tested steels, the values of reduction ratio of area are greater than 60%, except for 42CrMo which is slightly lower than 60% at 150 and 250°C
Summary
As the world’s most recognized effective method for heavy oil recovery, thermal recovery can further increase crude oil recovery and reverse the current situation of low recovery [1]. It is imperative to study and test the core technologies and key supporting tools for thermal recovery [2,3]. Stainless steels are usually used as tool steels for acid-resistant valves in petrochemical industry due to their high strength, welding ability, and high corrosion resistance [4,5]. In addition to high strength, they have high toughness and ductility. They can be used as high pressure flange, oil drilling pipe, and brake disc in oil recovery industry [7,8]
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