Siska Prifiharni

Tensile properties of the modified 13Cr martensitic stainless steels

This paper reports the influence of Mo and Ni on the tensile properties of the modified 13Cr martensitic stainless steels in tempered condition. Four steels with different content of Mo and Ni were prepared by induction melting followed by hot forging, quenching and tempering. The experimental results showed that the addition of about 1% and 3% Mo has a beneficial effect to increase both the tensile strength and the elongation of the steels. On the contrary, the addition of about 3% Ni into the martensitic stainless steel results in decreasing of both the tensile strength and the elongation. Among the alloys investigated the 13Cr3Mo type steel exhibited largest tensile strength of 1348 MPa and largest elongation of 12%. The observation on the tensile fractured surfaces by using scanning electron microscope supported these findings.

The effect of tempering temperature on pitting corrosion resistance of 420 stainless steels

The AISI Type 420 stainless steels are commonly used to steam generators, mixer blades, etc. These stainless steels are most prone to pitting in dissolved Cl− containing environments. In this paper, the effect of tempering temperature on pitting corrosion resistance of AISI Type 420 stainless steels was studied. The AISI Type 420 stainless steels specimens were heat treated at the temperature of 1050°C for 1 hour to reach austenite stabilization and then quench in the oil. After that, the specimens were tempered at the temperature of 150, 250, 350 and 450°C for 30 minutes and then air cooled to the room temperature. The electrochemical potentiodynamic polarization test was conducted at 3.5% sodium chloride solution to evaluate corrosion rate and pitting corrosion behaviour. The Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) were used to evaluate the pitting corrosion product. The result have shown that highest pitting potential was found in the sample tempered at 250°C and ...

Atmospheric corrosion performance of different steels in early exposure in the coastal area region West Java, Indonesia

The performance of carbon steel, galvanized steel and aluminium after one month exposed in the atmospheric coastal area, which is in Limbangan and Karangsong Beach, West Java, Indonesia was evaluat...

The hardness, microstructure, and pitting resistance of austenitic stainless steel Fe25Ni15Cr with the addition of tungsten, niobium, and vanadium

In this work, the effect of 2% W, 1%Nb, and 1% V addition on the hardness, microstructure, and pitting resistance to austenitic stainless steel Fe25Ni15Cr was investigated. The specimens were prepared in induction melting furnace, followed by homogenizing at 1100⁰C for 24 h. Then, the specimens were solution treated at 975⁰C for 2 h followed by water quenching and aging at 725⁰C for 15 h. The hardness was measured by using Rockwell hardness B, and metallographic observation was conducted using optical microscope and SEM-EDS. The results show that the increament of W, Nb, and V in the austenitic stainless steel Fe25Ni15Crby increased the hardness. The metal carbide precipitation occurred at grain boundaries in niobium free alloy. The addition of Nb in the alloy promotes the Laves phase transformation, and addition of V increase Nb content in the Laves phase. Laves phase formation in alloys containing niobium during aging heat treatments lead to an increase in hardness. Addition of W, Nb, and V also increase pitting resistance of the Fe25Ni15Cr austenitic stainless steel. This can be attributed to an increasing level of niobium in the matrix.In this work, the effect of 2% W, 1%Nb, and 1% V addition on the hardness, microstructure, and pitting resistance to austenitic stainless steel Fe25Ni15Cr was investigated. The specimens were prepared in induction melting furnace, followed by homogenizing at 1100⁰C for 24 h. Then, the specimens were solution treated at 975⁰C for 2 h followed by water quenching and aging at 725⁰C for 15 h. The hardness was measured by using Rockwell hardness B, and metallographic observation was conducted using optical microscope and SEM-EDS. The results show that the increament of W, Nb, and V in the austenitic stainless steel Fe25Ni15Crby increased the hardness. The metal carbide precipitation occurred at grain boundaries in niobium free alloy. The addition of Nb in the alloy promotes the Laves phase transformation, and addition of V increase Nb content in the Laves phase. Laves phase formation in alloys containing niobium during aging heat treatments lead to an increase in hardness. Addition of W, Nb, and V also increas...

Corrosion performance of steel and galvanized steel in Karangsong and Limbangan sea water environment

Due to wide spread use of steel and galvanized steelin Indonesia, it is important to study corrosion behavior of these materials in marine environments. Thus, corrosion performance of those materials was conducted in Karangsong and Limbangan. Since, the surface data was not available in the literature. Those materials were immersed in sea water for 27 days. The corrosion measurement was conducted by weight loss. Sea water parameter such as temperature, pH, salinity, DO (Dissolved Oxygen), and conductivity were measured. SEM-EDS was conducted to see corrosion morphology. The results showed that mild steel was more corroded than galvanized steel in both seawater environments. Corrosion rate of mild steel and galvanized steel in the Karangsong sea water were 29.5 and 8.4 mpy respectively, and corrosion rate of mild steel and galvanized steel in Limbangan sea water were 25.5 and 7.6 mpy respectively.Due to wide spread use of steel and galvanized steelin Indonesia, it is important to study corrosion behavior of these materials in marine environments. Thus, corrosion performance of those materials was conducted in Karangsong and Limbangan. Since, the surface data was not available in the literature. Those materials were immersed in sea water for 27 days. The corrosion measurement was conducted by weight loss. Sea water parameter such as temperature, pH, salinity, DO (Dissolved Oxygen), and conductivity were measured. SEM-EDS was conducted to see corrosion morphology. The results showed that mild steel was more corroded than galvanized steel in both seawater environments. Corrosion rate of mild steel and galvanized steel in the Karangsong sea water were 29.5 and 8.4 mpy respectively, and corrosion rate of mild steel and galvanized steel in Limbangan sea water were 25.5 and 7.6 mpy respectively.

Evaluation of anticorrosion and antifouling paint performance after exposure under seawater Surabaya–Madura (Suramadu) bridge

Antifouling paints are used widely to coat the underwater structures to prevent various fouling organisms. The evaluation of the performance for the two commercial anticorrosion and antifouling paints was carried out in the piles of Suramadu Bridge, East Java during 1 month exposure. The 20 cm width × 25 cm high × 0.3 cm thick specimens of mild steel were sandblasted and coated by anticorrosion and antifouling paint. Blank specimen (without exposed) were also prepared as a control. On the other hand, the 7.5 cm width × 15 cm high × 0.3 cm thick specimen bare mild steel was prepared for measure the corrosion rate throught weight loss method. The test panels containing specimens were exposure up to 1 month for immersion in splash zone and tidal zone (0, 1, 3, meters from sea level). Sea water parameters consisting of temperature, pH, salinity, conductivity and dissolved oxygen (DO) were also measured. The thickness, glossy, hardness and adhesion strength of the coating performance were carried out. The resu...