Abstract: This work describes an investigation on the effect of filler metals diameter to weld joint, and low alloy carbon steel A516 Grade 70 is the base metal. Commercially SA516 Grade70 is frequently used for the manufacturing of pressure vessels, boilers and storage tank, etc. In fabrication industry, the hardness of the weld joint is between the important parameters to check, after heat treatment of the weld. Submerged arc welding (SAW) is used with two filler metal diameters, and this solid wire electrode is used for SAW non-alloy and for fine grain steels (SFA 5.17). The different diameters were selected (Ø = 2.4 mm and Ø = 4 mm) to weld two specimens. Both specimens were subjected to the same preparation conditions, heat treatment, macrograph, metallurgy micrograph, and micro-hardness test. Samples show almost similar structure with highest hardness. It is important to indicate that the thickness used in the base metal is 22 mm, and all specifications, preparation and controls were according to the ASME section IX. It was observed that two different filler metal diameters performed on two similar specimens demonstrated that the mechanical property (hardness) increases with decreasing diameter. It means that even the heat treatment has the same effect with the same conditions, the filler metal diameter insures a depth weld penetration and better homogenization. Hence, the SAW welding technique mentioned in the present study is favorable to implicate for the industry using the small filler metal diameter.
Abstract: A group of Stellite alloys are studied in consideration
of temperature effects on their hardness and wear resistance. The
hardness test is conducted on a micro-hardness tester with a hot stage
equipped that allows heating the specimen up to 650°C. The wear
resistance of each alloy is evaluated using a pin-on-disc tribometer
with a heating furnace built-in that provides the temperature capacity
up to 450°C. The experimental results demonstrate that the hardness
and wear resistance of Stellite alloys behave differently at room
temperature and at high temperatures. The wear resistance of Stellite
alloys at room temperature mainly depends on their carbon content and
also influenced by the tungsten content in the alloys. However, at high
temperatures the wear mechanisms of Stellite alloys become more
complex, involving multiple factors. The relationships between
chemical composition, microstructure, hardness and wear resistance of
these alloys are studied, with focus on temperature effect on these
relations.