Larson Miller Parameter for the Prediction of the Creep Life of Unweld and Welded P91 Steel

For structural components that operate at elevated temperatures, martensitic P91 steel is preferable. It is widely used in steam generators in the fossil-fired thermal and nuclear power generation sectors due to its creep endurance and corrosion resistance. Several creep laws, such as Monkman-Grant, Theta project, Wilshire and Sinh model, Omega technique, and the Larson Miller Parameter (LMP),   have been developed over time to predict and failure of materials susceptible to the creep phenomenon. However, only the Omega Law and Larson-Miller Parameter are the only two methods approved in API 579-1. In this work, the creep test for welded and unwelded P91were conducted at temperatures of 600°C under stresses of 165, 175 MPa, and 190 MPa. In comparison to the welded specimens, the unwelded specimens displayed a continuously more substantial development of creep strain with time, resulting in a higher steady-state creep rate and a shorter rupture life. The increased magnitude of creep-rupture data has been observed to impact the dependability of creep life. Because of more significant changes in service temperature and stress conditions, the dependability of P91 steel has deteriorated, as well as an increase in creep life. The rupture life has been predicted using the LMP method, which utilizes the constant C parameter. At the same stress, the predicted creep life for weld material shows a higher value than that of the parent material, which is consistent with the experimental result

Larson Miller Parameter for the Prediction of the Creep Life of Unweld and Welded P91 Steel

For structural components that operate at elevated temperatures, martensitic P91 steel is preferable. It is widely used in steam generators in the fossil-fired thermal and nuclear power generation sectors due to its creep endurance and corrosion resistance. Several creep laws, such as Monkman-Grant, Theta project, Wilshire and Sinh model, Omega technique, and the Larson Miller Parameter (LMP),   have been developed over time to predict and failure of materials susceptible to the creep phenomenon. However, only the Omega Law and Larson-Miller Parameter are the only two methods approved in API 579-1. In this work, the creep test for welded and unwelded P91were conducted at temperatures of 600°C under stresses of 165, 175 MPa, and 190 MPa. In comparison to the welded specimens, the unwelded specimens displayed a continuously more substantial development of creep strain with time, resulting in a higher steady-state creep rate and a shorter rupture life. The increased magnitude of creep-rupture data has been observed to impact the dependability of creep life. Because of more significant changes in service temperature and stress conditions, the dependability of P91 steel has deteriorated, as well as an increase in creep life. The rupture life has been predicted using the LMP method, which utilizes the constant C parameter. At the same stress, the predicted creep life for weld material shows a higher value than that of the parent material, which is consistent with the experimental result

Finite Element Modelling of Creep Rupture on Grade 91 Steel using Monkman-Grant Ductility based Damage Model

Failure strain is a main parameter used in the ductility exhaustion based damage model in which the accuracy of the prediction is dependent on its input value. The experimental measured has indicated that the value of strain at fracture is extensively scattered, therefore may affect the prediction. This paper presents the result of creep rupture time using a modified creep damage model incorporating Monkman-Grant (MG) failure strain as an alternative to strain at fracture. Both strains at fracture and MG failure strain are separately employed in the damage model to predict the failure time of uniaxial smooth specimen and notched bar with different acuity ratios of 3.0 and 20. The FE model of the specimen is loaded under different stress values and the multiaxial failure strain at each stress level is estimated using Cock and Ashby void growth model. The predicted creep rupture time that is compared to the experimental data (in a range of 40-1000 hours) showing a good agreement within the scatter band of +/- factor of 2. Both approaches using strain at fracture and MG failure strain can be used in predicting the creep failure under uniaxial and multiaxial features. The advantage of using MG strain is that the laboratory creep testing can be interrupted prior to specimen fractured or once the secondary creep deformation occurs. Meanwhile, the determination of strain at fracture needs longer test duration where the test can be stopped only when the specimen broken

Montmorillonite (MMT) nanoclay in smart coatings for corrosion protection of metal alloy

Montmorillonite (MMT) nanoclay is a natural raw material naturally occurring 2-dimensional lamellar silicate material. Many advantages of MMT clay are low cost, high dispersion properties, good mechanical properties, hydrophobic, good shield against corrosive media, non-toxic, easily accessible, and most importantly, it is natural. MMT was mainly used as an additive with other active smart materials to enhance the excellent properties for smart coatings. However, there is not much research done from the last 5 years regarding MMT in smart coating for corrosion protection. The discussion regarding MMT for corrosion protection is also contradict between each research. This paper provides a brief review on MMT clay in smart coatings and its advantages for corrosion protection for the last 5 years. There are also some drawbacks of MMT in smart coatings discussed at the end. Further research needs to be done as MMT has more potential that can be used in the real-world industries and to clarify the contradiction of statement existed in much research

Autonomous navigation of mobile robot using kinect sensor

The problem of achieving real time process in depth camera application, in particular when used for indoor mobile robot localization and navigation is far from being solved. Thus, this paper presents autonomous navigation of the mobile robot by using Kinect sensor. By using Microsoft Kinect XBOX 360 as the main sensor, the robot is expected to navigate and avoid obstacles safely. By using depth data, 3D point clouds, filtering and clustering process, the Kinect sensor is expected to be able to differentiate the obstacles and the path in order to navigate safely. Therefore, this research requirement to propose a creation of low-cost autonomous mobile robot that can be navigated safely

METODE SELF HYPNOSIS UNTUK MENGATASI STRES MAHASISWA AKHIR JURUSAN BIMBINGAN DAN PENYULUHAN ISLAM PADA FAKULTAS DAKWAH DAN KOMUNIKASI UIN ALAUDDIN MAKASSAR

The study discusses the Self Hypnosis Method in dealing with the stress of final students majoring in Islamic guidance and counseling at the da'wah and communication faculty with subproblems, namely; (1) what causes final student stress, (2) how is the method of self-hypnosis in dealing with final student stress. (3) how are the obstacles in doing self-hypnosis and the solutions. The results of this study indicate that the causes of stress for final students at the da'wah and communication faculty are time pressure, difficulty finding supervisors, difficulty in finding references, and fear of work. The method of self-hypnosis in dealing with stress in students, namely relaxation, self-programming, and termination is done before going to bed and before leaving for campus

Finite Element Modelling of Creep Rupture on Grade 91 Steel using Monkman-Grant Ductility based Damage Model

Failure strain is a main parameter used in the ductility exhaustion based damage model in which the accuracy of the prediction is dependent on its input value. The experimental measured has indicated that the value of strain at fracture is extensively scattered, therefore may affect the prediction. This paper presents the result of creep rupture time using a modified creep damage model incorporating Monkman-Grant (MG) failure strain as an alternative to strain at fracture. Both strains at fracture and MG failure strain are separately employed in the damage model to predict the failure time of uniaxial smooth specimen and notched bar with different acuity ratios of 3.0 and 20. The FE model of the specimen is loaded under different stress values and the multiaxial failure strain at each stress level is estimated using Cock and Ashby void growth model. The predicted creep rupture time that is compared to the experimental data (in a range of 40-1000 hours) showing a good agreement within the scatter band of +/- factor of 2. Both approaches using strain at fracture and MG failure strain can be used in predicting the creep failure under uniaxial and multiaxial features. The advantage of using MG strain is that the laboratory creep testing can be interrupted prior to specimen fractured or once the secondary creep deformation occurs. Meanwhile, the determination of strain at fracture needs longer test duration where the test can be stopped only when the specimen broken

Development of smart self-healing coating for the corrosion protection of magnesium alloys: a brief review

The combination of excellent physical qualities and biocompatibility has made magnesium (Mg) alloys a viable light alloy, particularly for automotive, aerospace, and pharmaceutical applications. However, in most environments, Mg alloys are easily corroded, thus preventing their extensive use. Surface protection by coating is an affordable method for preventing corrosive media from contacting Mg substrate. The development of smart self-healing coatings has attracted attention for surface coating of Mg alloys, as it can impede corrosion reactions, repair mechanical damage, and enable the substrate to function normally again. This article briefly reviews the promising approach of smart self-healing coatings, state-of-the-art coatings, and various healing agent encapsulations. Polymerizable healing agents or corrosion inhibitors are encapsulated in containers and embedded in the coating matrices to facilitate autonomous healing mechanisms. This brief explanation and review are expected to give an insight and more opportunities to explore newly designed smart self-healing coatings

Applying TRIZ to design and develop roof shield for two-wheeled motorcycle

Online purchasing and food delivery have shown an increase in demand during the pandemic COVID-19. In Malaysia, the most preferred mode of transportation for food delivery is motorcycle. However, the hot weather and rain affect the delivery time. This paper presents the effort to design and develop a roof shield for a motorcycle to tackle the problem of delivery during uncertain weather conditions. A survey was conducted around Pekan and Kuantan, Pahang districts, encompassing a total of 100 respondents, including riders and customers. From respondents’ feedback, the design requirements for the roof shield were derived. Two conceptual designs were sketched based on the TRIZ approach and evaluated using the scoring test matrix. The roof shield is designed so that it is height adjustable and expandable to fit different brands of motorcycles, which have slightly different dimensions. Furthermore, the rotatable roof is developed to improve riding, especially during cornering. The fabricated roof was assembled on the AVETA DY90 and DEMAK EX90 motorcycles. Twenty random riders were chosen to test the roofed motorcycle on the road. The feedback collected from them showed overall satisfaction with the roof shield installed on the motorcycle. They believed that the roof can protect them from the sun’s rays and light rain thereby increasing delivery performance. The suggestion by the rider to further improve the roof is being considered for future design

Creep life prediction of P91 steel using omega method

Martensitic P91 steel is desirable for structural components operating at elevated temperatures. It is extensively used in nuclear power plant boilers, pipelines, reactor pressure vessels, and steam generators due to its high creep strength and corrosion resistance. Predicting the P91’s creep rupture life is critical for safe operation. Numerous creep laws have been developed throughout the years to anticipate the deformation, propagation of damage, and rupture of materials subjected to the creep phenomena. The Omega method is one of the most widely used in API RP579 on fitness-for-service purposes. In this study, the creep tests have been performed at 600 °C for 160, 180 and 190 MPa. In order to predict the rupture life, the omega method has been employed, which utilised the initial creep strain rate and creep strain. The experimental data has been compared to available literature data for P91 material. The predicted life was always more significant than the experimental result, and it was strongly linked to the omega value. The result shows that the value omega value of the test data are in line with the available data and the initial creep strain rate increased linearly with increased of stress and temperature. The predicted rupture life values are consistent and close to the experimental results