Mechanichal Porperies of Boiler Tubes ( T91 AND T92)

• Main Author: Kalairasan A /l Anparassan
• Published: 2023
• Subjects: Mechanical properties; Boiler tubes

In this modern days, there are plenty of reasons for failure of boiler tubes in power plant in Malaysia. One of the main concern is the material use as boiler tube and it’s mechanical properties. T91 and T92 is a ferritic-martensite alloy steel. This material has a good tensile strength and good mechanical properties. This material has been used as boiler tube at several power plant. Due to some reasons, this material became a failure as the boiler easily tend to crack or break. So, the mechanical properties of the boiler tube were tested. The tests which were conducted were tensile test, hardness testing and microstructure analysis using etching process. Tensile test was done using Zwick universal tester in which it gives the Modulus strength and the value of ultimate strength (MPa). By using that, the shear-strain graph was obtained. Hardness test where done using Brinell method as it is the best method to get the HB value of the materials. It’s about the penentration depth and force applied. As for the microstructure analysis, it was done using etching process. The etchant used was Nital Etch since it is most suitable etchant to be used for this material. It was found that T92 has greater ultimate strength value which is 450MPa compare to T91. As for the hardness test, T92 is stronger, has greater HB value compare to T91. The HB value of T92 is 233 whereas the HB value for T91 is 221. The microstructure analysis was done and it was clearly observed since it was done grinding, polishing and etching process. The carbide and precipitates were clearly seen. In terms of mechanical properties, T91 and T91 has good mechanical properties since they have strong ultimate strength and also both has a strong HB values.