Corrosion

Comparing corrosion-resistant HK & HH steels in Riverbed Furnace Atmosphere

Hossein nasab Saeed , Iran nejad Ahmad

1- A student of Materials-Corrosion Engineering group & protecting materials (M.A), Sciences & Researches University, Sirjan City

2- Professor of Materials-Corrosion Engineering group & protecting materials, Bahonar University, Kerman City

Abstract:

Hopper third part piece of Riverbed furnace which is in hot and corroding atmosphere of Riverbed furnace containing oxide and sulphide, is made of fireproof steel and is compared with HK steel from corrosion-resistance view. Of every kind two 200×200 mm plates in thickness of the same hopper were casted and after polishing they were cut as 200×30mm coupons, washed by acetone and alcohol, then weighted by scale. Coupons hang on Riverbed furnace roof for field test. After a certain time, coupons influenced by high heat and corroding gases were weighted and a difference was obtained. Corrosion speed was calculated based on mm/year. Studies show that corrosion speed of HK steel is less in this atmosphere. XRD analysis shows that oxides formed on surface aren’t constant in high temperature which can prevent corrosion. Nickel is completely taken from the piece in coupons after field test and point analysis and doesn’t show nickel corroded pints. Non-nickel corroded points determine that ferrite-nickel-chrome can’t act well in sulphate environment and pieces are formed as leaky cheese.

Keywords: Fireproof steel, Hopper, Corrosion, Weighting, Acetone, Alcohol

Defects

Studying the effect of Sarcheshmeh Copper Complex Riverbed Furnace Atmosphere on defects of HK & HH steels

Hossein nasab Saeed , Iran nejad Ahmad

1- A student of Materials-Corrosion Engineering group & protecting materials (M.A), Sciences & Researches University, Sirjan City

2- Professor of Materials-Corrosion Engineering group & protecting materials, Bahonar University, Kerman City

Abstract:

According to ACI standard H heat-resistant alloys should bear temperatures higher than 1100 Cº in high temperature corroding environments. Regarding type and conditions of duel combustion in torches, flame furnace atmosphere is varied from neutral to weak oxidized state. Chromate and slag are formed as a result of reaction between sulphides, oxides, copper and ferrite sulphates. This research studies the effect of Riverbed Furnace Atmosphere on defects of HK & HH steels. From both products one 200×200 mm plate was casted. Coupons were cut in 200×30 mm size and hung from Riverb Furnace roof for field test. After one month coupons influenced by high heat and corroding gases were exited from furnace and structured by point and SEM analysis. As a result regarding EDAX analysis, oxide and sulphide defects as well wastes are observed. Because of high chrome percent in chemical composition of sample are as chrome base. In used samples of HH coupons and HH hoppers, considerable cracks were observed after placing in furnace atmosphere. Microscopic defects containing crack, waste and holes in HK sample are less than HH sample.

Keywords: Fireproof steel, Hopper, Waste, Crack, Oxide defects

Mechanical characteristics

Studying the effect of Sarcheshmeh Copper Complex Riverbed Furnace Atmosphere on mechanical characteristics of HK & HH steels

Hossein nasab Saeed , Iran nejad Ahmad

1- A student of Materials-Corrosion Engineering group & protecting materials (M.A), Sciences & Researches University, Sirjan City

2- Professor of Materials-Corrosion Engineering group & protecting materials, Bahonar University, Kerman City

Abstract:

Heat-resistant steels are variously applied in several industries for high resistance against oxidation and slipping. This research studies the effect of Riverbed Furnace Atmosphere on chemical characteristics of HK & HH steels. Some factors such as tension stability, shock-resistance, and micro- and macro hardness were studied. Experiments were done in ambient temperature and some microscopic observations were structured by optical microscope and SEM. Riverbed furnace environment was measured and corroding gases were recognized in this environment. Studies show that samples stability reduced after field test and pieces were more brittle, for example flexibility,. Length increase and tension stability reduced. This reduction is for presence of mass carbide sediments and increasing chrome percent raises carbide rate. In this regard stability of these steels especially slipping stability is improved in high temperature.

Keywords: Heat-resistant steel, Mechanical experiments, stability

Steel substructures

Studying the effect of heat activities on substructures of HK & HH steels

Hossein nasab Saeid , Iran nejad Ahmad

1- A student of Materials-Corrosion Engineering group & protecting materials (M.A), Sciences & Researches University, Sirjan City

2- Professor of Materials-Corrosion Engineering group & protecting materials, Bahonar University, Kerman City

Abstract:

Alloys for which chrome rate is more than nickel, this group of alloys are able to work in oxidation conditions and resistant to mean temperature changes. In general, resistant alloys to heat are more alloyed than non-rusted alloys and need more carbon. Also, they show better mechanical characteristics in higher temperatures for presence of carbide sediment. These alloys are well resistant to oxidation, corrosion and sulphated conditions for increasing chrome, while they are also high resistant to heat shocks and slipping for presence of nickel. Generally application environments of these alloys contain air, sulphuric and non-sulphuric gases. In this research the effect of heat activities on HK & HH steel structures is studied. From both products one 200×200 mm plate was casted. Then a sample was prepared and was studied to observe microscope structure before and after heat activities.

Studies show that mass carbides and assembly of carbide sub-particles are clearly observed in HK & HH samples. Mass carbide present in samples found a better distribution by heat activities and fast refrigeration of carbides. Connected carbides dissolve by heat activities and dissipate in the field spherically and prickly and structure will be improved. Lack of chemical equilibrium causes to standard deviation and is accompanied by ferrite and austenite phases and finally disconnection of alloy elements. Chemical equilibrium between ferrite- and austenite-produced alloy elements leads to a completely austenite field.

Keywords: Fireproof steel, Microscopic structure, Carbide