Effect of Electrode Type for SMAW Welding on ASTM A36 Steel to

Reduce Bio-corrosion Rate in Marine Environment

Herman Pratikno

, Harmin Sulistiyaning Titah

and Muhammad Sultanul Azdkar

Department of Ocean Engineering, Faculty of Marine Technology, Institut Teknologi Sepuluh Nopember,

Keputih, Sukolilo, 60111 Surabaya, Indonesia

Department of Environmental Engineering, Faculty of Civil, Environmental and Geo Engineering,

Institut Teknologi Sepuluh Nopember, Keputih, Sukolilo, 60111 Surabaya, Indonesia

Keywords: Bio-corrosion Rate, SMAW Welding, ASTM A36 Steel.

Abstract: The construction of the maritime industry, especially the manufacture of offshore building, at the moment

mostly use the technique of metal welding. Weld joints on steel materials cannot be separated with the

corrosion. Corrosion can cause a decrease in strength of materials and damage to construction. Corrosion is

the degradation of metal caused by an electrochemical reaction between the metal with the surrounding

environment. One of the causes of corrosion was bacteria, it was called as bio-corrosion. The bacteria live in

the marine environment were widespread in their habitat and form a colony and then stick on the metal surface

in the form of a thin layer. The aim of the research was to determinate the corrosion rate of the weld type

SMAW on steel ASTM A36 with variations of the electrode. The variations of the electrode were AWS

E6010, AWS E6013, AWS E6019. The corrosion test was conducted using immersion corrosion test method.

The welded joints of materials were be soaked in artificial sea water with a salinity of 35‰ with Thiobacillus

ferrooxidans addition and without bacteria addition as a control. The resistance on bio-corrosion rate was

determined using weight loss method. The results showed the lowest of bio-corrosion rate with the addition

of the Thiobacillus ferrooxidans on welded joints of materials was AWS E6013 compared with other

electrodes. It reached 9.79757 mpy. Similarly, the lowest of corrosion rate (7.48178 mpy) without

Thiobacillus ferrooxidans addition was AWS E6013. Based on microstructure results, uniform and pitting

corrosion occurred on all welded joint specimens with the addition of bacteria or without the addition of

bacteria. However, the corrosion rates were different. It indicated that AWS E6013 as a electrode on SMAW

welding on ASTM A36 steel has a high effect to reduce the corrosion and bio-corrosion rate in marine

environment.

1 INTRODUCTION

The construction of the maritime industry, especially

the manufacture of building offshore at the moment

mostly use the technique of metal welding. This

welding technique is not a new knowledge but it is

something of basic needs. Therefore, the welding

process should be conducted with the right method to

get maximum results and satisfactory. Welding is a

technique of connection between the metal become

one and strong. Based on the definition of DIN

(Deutch Industrie Normen) welding is a metallurgical

bonding on the connection of a metal alloy was

carried out in the circumstances of the melt or liquid.

At this time, there are 40 types of welding, one of

which is Shielded Metal Arc Welding (SMAW) or

welding electrodes encased. However, the weld joints

on steel materials cannot be separated with the name

of corrosion. Corrosion can cause a decrease in

strength of materials and damage to construction.

Corrosion is the degradation of metal caused by

an electrochemical reaction between the metal with

the surrounding environment (Trethewey and

Chamberlain, 1991). Corrosion can also be

interpreted as the events of nature that occured on the

material and is the process of the return of the material

to its original condition when the material is found

and processed from nature (Supriyanto, 2007).

Quickly than a material corroded is closely related to

the corrosion rate while the corrosion rate itself on the

environment is neutral normally is equal to 1 mpy or

less. The rate of corrosion is influenced by several

Pratikno, H., Titah, H. and Azdkar, M.

Effect of Electrode Type for SMAW Welding on ASTM A36 Steel to Reduce Bio-corrosion Rate in Marine Environment.

DOI: 10.5220/0008649801650169

In Proceedings of the 6th International Seminar on Ocean and Coastal Engineering, Environmental and Natural Disaster Management (ISOCEEN 2018), pages 165-169

ISBN: 978-989-758-455-8

165

factors, among others: water, gas content and

dissolved solids, temperature, material selection, pH,

reducing bacteria or Sulfate Reducing Bacteria

(ASM, 2003).

In the marine environment the corrosion rate is

quickly increased, it is because the sea water contains

dissolved substances that are able to dissolve other

substances in larger quantities than other liquids.

Dissolved substances include inorganic salts, organic

compounds derived from living organisms (bacteria)

and dissolved gases. One of the causes of corrosion is

bacteria. The live bacteria in the marine environment

are widespread in their habitat and form a colony and

then stick on the metal surface in the form of a thin

layer. Microorganisms that affect the process of

corrosion is divided into two types, namely aerobic

and anaerobic bacteria. The bacteria form a colony on

the surface of the metal to the place of their lives.

These colonies form a layer (biofilm) on the surface

of the material so that the material becomes corroded

a result of life activity of microorganisms.

The purpose of the research was to determinate

the corrosion rate of the weld type SMAW on steel

ASTM A36 with variations of the electrode. In this

study, the sea water used artificial sea water with a

salinity of 35 ‰ with the addition of bacteria

(Thiobacillus ferrooxidans).

2 MATERIALS AND METHODS

2.1 Preparation of Steel Material of

ASTM A36

The material that was used in this study was a steel

material ASTM A36 mild steel. Test specimens were

made in the shape of a rectangle with the size

dimensions as follows length of 300 mm, width of

150 mm and thickness of 6 mm, and the shape of the

weld groove was Single V-Groove with 60o. The

variations of the electrode were AWS E6010, AWS

E6013, AWS E6019.

2.2 Preparation of Welding

WPS (Welding Procedure Specifications) was

prepared based on the welding procedures (Standard

AWS D1.1, 2015). It was conducted to get results of

the welds in accordance with the desired. Making

WPS refers to the about the procedure of welding

steel.

2.3 Hardness Testing

The hardness test was conducting to all specimens

using Vickers method. Vickers Hardness Test is the

standard method for measuring the hardness of

metals, particularly those with extremely hard

surfaces: the surface is subjected to a standard

pressure for a standard length of time by means of a

pyramid-shaped diamond. The diagonal of the

resulting indention is measured under a microscope.

2.4 Preparation of Bacteria

The preparation of bacteria was conducted based on

Pratikno and Titah (2016). The pure culture of

Thiobacillus ferrooxidans was be inoculated onto

nutrient agar (NA) media using streak plate technique

based on Harley and Prescott (2002). The age of

bacteria for the test was 24 h. After that, one colony

of bacteria was transferred to nutrient borth (NB) and

keep in shaker incubator of Innova 2000 (New

Brunswick-Eppendorf, Germany) at 150 rpm and

room temperature, 33 oC for 24 h. The cell

suspension of selected bacteria was prepared by

harvesting the cells at the middle of the logarithmic

phase, based on the typical of growth rate graph for

the selected bacteria. At this time, the OD at 600 nm

was 1.0 was determined using UV spectrophotometer

Genesys 20 (Thermo, USA). The cells were harvested

through centrifugation of Jouan E82 (Thermo, USA)

at 4,000 rpm for 15 min. The obtained pellet was then

washed twice using 8.5 g NaCl/1000 mL solution.The

suspension of bacteria was ready to be used in bio-

corrosion test.

2.5 Preparation of Bio-corrosion Test

This research used a chemical solution instead of sea

water with a salinity of 35 ‰. The chemical

composition of seawater replacement is in accordance

with ASTM D1141-90 (2004). The specimen was

tested by immersion technique in a prepared seawater

solution with salinity of 35‰ using ASTM G31-72

standard (2004). Immersion testing was conducted in

beaker glass with size of 300 mL and the artificial

seawater was 250 mL for each beker glass. The

welded joints of materials were be soaked in artificial

sea water with a salinity of 35 ‰ with Thiobacillus

ferrooxidans addition and without bacteria addition as

a control for 1 week.

ISOCEEN 2018 - 6th International Seminar on Ocean and Coastal Engineering, Environmental and Natural Disaster Management

166

2.6 Calculation of Corrosion Rate

Running rate of corrosion is a rapid propagation of

material quality decline against time. There is a

formula for calculating the corrosion rate based on the

ASTM G1-03 standard (2002) as follows:

𝐶𝑜𝑟𝑟𝑜𝑠𝑖𝑜𝑛 𝑟𝑎𝑡𝑒



𝑚𝑝𝑦





  

    

( 1 )

With

K = Constanta

T = Time of exposure (h)

A = Surface area (cm2)

W = Weight loss (gram)

D = Material density (gram/cm3)

2.7 Microstructure Observation

After corrosion testing was conducted, the

microstructure of specimens were determined using a

microscope for detailed morphology of the specimen

structure. It was used for documentary evidence and

it can be known that the specimen differences

between before and after testing.

3 RESULTS AND DISCUSSION

3.1 Hardness Test

Figure 1 depicted the results of hardness test on

welded ASTM A36 with variations of the electrode.

The highest hardness value on welded ASTM A36

was 164.00 VHN with electrode E6013. In the area of

heat influence (Heat Affected Zone), the highest

hardness value occurred in welding with E6019

electrode, it reached 157.43 VHN. Whereas in the

base metal, the highest hardness value occurs in

welding with E6019 electrode (150.19 VHN). The

average of hardness value of the specimens in all

electrode variations increased when compared with

the parent metal. However, the type electrode of

E6013 has the highest hardness value. According to

Allen (Allen, 2018), the material was more harder can

cause more higher of the tensile strength, higher of

the level of brittleness (brittle) and less of the ductile.

The hardness of a material was directly proportional

to strength and brittleness, but it was inversely

proportional to its ductility.

Figure 1: Results of hardness test on ASTM A36 with

variations of the electrode.

3.2 Bio-corrosion Test

Figure 2 showed the bio-corrotion rate on welded

ASTM A36 with variations of the electrode.

According to Figure 2, the bio-corrosion showed the

higher value when compared with corrosion rate

without Thiobacillus ferroxidans addition. The

variation type of electrode showed the difference on

corrosion rate on welded joints of materials. The bio-

corrotion rate with electode of AWS E6013 reached

9.79757 mpy. Similarly, the lowest of corrosion rate

(7.48178 mpy) without Thiobacillus ferrooxidans

addition was AWS E6013. Based on Pratikno and

Titah (2016), 3 species of bacteria Escherichia coli,

Pseudomonas fluorescens, and Thiobacillus

ferroxidans can caused bio-corrosion on steel

structures of ASTM A106 and A53 in deep seawater

(salinity of 33‰), medium seawater (salinity of

35‰), and shallow seawater (salinity of 37‰)

(Pratikno and Titah, 2016). The bio-corrosion rate by

Pseudomonas fluorescenson Aluminium Alloy 6063

at salinity of 37‰ increased by one point six-fold

compared with the condition without bacteria

addition at the same salinity (Pratikno and Titah,

2016). Based on the resultas of corrotion rate and bio-

Figure 2: Bio-corrosion rate on ASTM A36 with variations

of the electrode.

Effect of Electrode Type for SMAW Welding on ASTM A36 Steel to Reduce Bio-corrosion Rate in Marine Environment

167

corrotion rate (7,48178 - 9,79575 mpy), it can be

concluded that all the material included in the

category of good (better). According to Fontana

(1987), the level of corrosion resistance based on

corrosion rate of 5 – 20 mpy was good.

3.3 Microstructure Observation

Microstructure showed that appearance of corrosion

on specimen. According to Figure 3, the corrosion on

the specimens test were pitting and uniform

corrosion. There was a difference of pitting corrosion

in specimens immersed at difference of electrode

type. However, uniform and pitting corrosion

occurred on all welded joint specimens with the

addition of bacteria or without the addition of

bacteria. Although the corrosion rates were different.

(a)

(b)

(c)

(d)

(e)

(f)

Figure 3: Microstructure on welded ASTM A36 with

variations of the electrode, (a) non bacteria, (b) with

bacteria with electrode of E6010, (c) non bacteria (d) with

bacteria with electrode of E6013, and (e) non bacteria , (f)

with bacteria with electrode of E6019.

4 CONCLUSION

The results showed the lowest of bio-corrosion rate

with the addition of the Thiobacillus ferrooxidans on

welded joints of materials was AWS E6013 compared

with other electrodes. Similarly, the lowest of

corrosion rate or without Thiobacillus ferrooxidans.

The value of bio-corrosion and corrosion rate were

9.79757 mpy and 7.48178 mpy, respectively. The

type electode of E6013 has the highest hardness value

(164 HVN). Based on microstructure results, uniform

ISOCEEN 2018 - 6th International Seminar on Ocean and Coastal Engineering, Environmental and Natural Disaster Management

168

and pitting corrosion occurred on all welded joint

specimens with the addition of bacteria or without the

addition of bacteria. However, the corrosion rates

were different. It indicated that AWS E6013 as a

electrode on SMAW welding on ASTM A36 steel has

a high effect to reduce the corrosion and bio-

corrosion rate in marine environment.

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