Study of Microstructure and Mechanical Property Degradation of SA210 A1 Boiler Tube

The comprehension of the microstructure change and mechanical property degradation are of particular importance for assessing the integrity of aging boiler tubes.This paper describes the investigation of microstructure evolution and mechanical property degradation of SA210 A1 steel used in an actual boiler condition. The investigation deals with visual inspection, chemical composition analysis, micrograph study using Energy Dispersive Spectroscopy-Scanning Electron Microscopy (EDS-SEM), tensile test and hardness test. The result showed that the prolonged operating period in the high temperature condition resulted in the reduction of the mechanical properties of the SA 210 A1 steel tube. The study also indicated the presence of the onset of the pearlite disintegration and coagulation, resulted from the microstructure degradation of the aged steel tube after the elevated temperature service in a boiler

Grain Refining Effect of Al-5Ti-1B Master Alloy on Microstructures and Mechanical Properties of A356 Alloy

In this study, the structures of Al-5Ti-1B master alloy and its influence on microstructures and mechanical properties of A356 alloy were investigated. The results show that Al-5Ti-1B master alloy consisted of the uniform distribution of lump-like TiB2 and network of TiAl3 on α-Al matrix. The addition of the Al-5Ti-1B master alloy can significantly reduce the grain size of A356 alloy. The mechanical properties of A356 alloy, i.e. ultimate tensile strength, yield strength and elongation were also improved. The use of Al-5Ti-1B master alloy as a grain refiner in the casting process of A356 alloy can effectively enhance the grain refinement and thus improve the mechanical performance of A356 alloy.</jats:p

Cryogenic treatment of tool steels: A brief review and a case report

Tool steels used in marine industries demand for the effective approach to enhance their properties. Normally, conventional heat treatment is widely used to increase the performance of tool steels. However, this method cannot fully enhance the tool steel performance. On the other hand, cryogenic treatment is a supplementary process to the conventional heat treatment, which can promote the conversion of retained austenite to martensite and accelerate the precipitation of fine carbides. In this paper, a systematic review of cryogenic treatment of tool steels was presented. A wide range of useful investigations was reviewed, particularly in the details of the transformation of retained austenite to martensite and the precipitation of the fine carbides. A case study on a tool steel subjected to conventional heat treatment, conventional cold treatment, and deep cryogenic treatment was also given and discussed to give an insight in the cryogenic treatment of tool steels.</jats:p

Study on carburized steel used in maritime industry: The influences of carburizing temperature

This paper aims to examine the influence of carburizing temperature on carburized mild steel. Carburizing treatment was carried out at carburizing temperatures of 800 and 900 °C with fixed carburizing time of 1 h. The results indicated that carburization treatment could improve the hardness of the samples. However, it was found that the hardness profile of mild steel was almost unchanged after treatment at the carburizing temperature of 800 °C. Carburization treatment carried out at the carburizing temperature of 900 °C could significantly enhance the hardness conditions and also increase the case depth of carburized mild steel. Carburized steel can provide a tough and durable surface to protect against severe degradations, such as marine erosion, wear, and cavitation in maritime applications.</jats:p

Effect of Ammonium Sulphate ((NH&lt;sub&gt;4&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt; SO&lt;sub&gt;4&lt;/sub&gt;) on Microstructure and Mechanical Properties of SA-213-Gr.T22 and SA-210-Gr.A1 Steel in the Water Tube Boiler

This paper presents the effect of an Ammonium sulphate (NH4)2 SO4) leak mixed in the boiler feed water system on the microstructure, chemistry, metallurgy and mechanical properties of the water tube boiler. Tube specimens were water tube and super-heated tube materials made from ferritic-pearlitic steel alloy grade SA-210-Gr.A1 and ferritic steel grade SA213-Gr.T22, respectively. Specimens were obtained from different height levels of the boiler and tested. The results from the emission spectrometer revealed that the carbon (C) and sulfur (S) did not concentrate inside the tube during five days of operation. Whereas the operating temperature causes the change in the microstructure and mechanical properties due to a segregation of phase and change of mechanical properties (hardness and tensile) in the used tube.</jats:p

A metallurgical investigation on a failed superheater tube used in a thermal biomass power plant

This article described the investigation of the failed superheater tube made of SA210 Grade C used in a biomass power plant. Visual inspection, microstructural examination, chemical analysis and hardness measurement were employed to analyze the causes of the superheater tube failure. Results from the investigation showed that the major cause of this failure was mainly related to the long-term overheating, resulting in the occurrence of the excessive thermal oxidation and graphitization. The excessive thermal degradation accelerated the reduction of the wall tube and promoted the build-up of the stress acting on the tube. Graphitization degraded the microstructure of the tube, reducing the mechanical performance of the tube. The combined effects from the severe thermal oxidation and graphitization attributed to the premature failure of the tube. It is therefore advised to use the correct material, SA213 T22, in the failed section. Material specification examination for superheater regions prior to tube installations should be performed to avoid the use of the inappropriate material. The temperature monitoring and mapping in this section were also suggested.</jats:p

The effects of energizer and carburizing temperature and time on mechanical properties of hardened big knives in the pack carburizing process

The purpose of this research is to study the effects of energizer and carburizing temperature and time on the mechanical properties of hardened big knives in the pack carburizing process. The mechanical properties of carburized and hardened big knives were compared to those of commercial hardened big knives made from leaf-spring steel that were forged, ground and quenched following the traditional forging processes. The experiment was conducted by forging big knives made of low carbon steel (grade AISI 1010). The first group of them was then pack-carburized using 10% by weight of calcium carbonate with 90% by weight of eucalyptus charcoal. The second group used 10% by weight of egg shell with 90% by weight of eucalyptus charcoal. The carburizing temperatures were 900, 950 and 1,000°C, with carburizing times of 30, 60 and 90 minutes followed by air cooling. The austenitizing temperature was 780°C with a holding time of 20 minutes, followed by quenching in water. Finally, the big knives were tempered at 180°C for 1 hour. Micro-Vickers hardness testing, impact testing and microstructure inspection were carried out. The results of this experiment show that the hardness of hardened big knives increased with an increase in the carburizing temperature and time. In contrast, the impact value of carburized steel decreased with an increase in the carburizing temperature and time. The hardness derived from using CaCO3 is slightly harder than that from using egg shell, however, the impact energy is higher when using egg shell, compared to using CaCO3