Technology of Iron Hardening by using the Pressure and Heating

Technique

Sutrisno

, Agus Budiono

and Tati Zera

Program Studi Fisika ,Fakultas Sains dan Teknologi, UIN Syarif Hidayatullah Jakarta, Banten, Indonesia

Keywords: technology; surface hardening; iron

Abstract: Iron surface hardening technology is done with a particular technique to minimize oxygen in order to avoid

the formation of oxide compounds that can inhibit the diffusion process and reduce the reactivity between

the iron and the reinforcement material. Conventionally, this technique is done by creating an inert gas

conditions using argon gas flow, or it can also be done by creating a system under vacuum conditions during

heating. This technique is operationally costly because it must provide argon gas or vacuum machines are

expensive. This study is intended to reduce the magnitude of these costs using the new methods with less

operational costs. In this study, iron surface hardening process conducted by using mechanical pressure and

heating without vacuum or argon gas flow. Samples iron S45C to be hardened is placed in a container

shaped cylindrical tube made of 304 stainless steel and covered with a powder mixture consisting of 5%

boron carbide (B

C), 90% of silicon carbide (SiC), and 5% potassium boron fluoride (KBF

) under certain

pressure. Samples were prepared is heated at a temperature of 700, 800, and 900

C with heating time for 8

hours. Layer formed on the metal surface can be identified as a layer of iron borides I (FeB) on the surface

and a layer of iron borides II (Fe

B) at certain depths. From the micro hardness test results using Vikers

identor expected to obtain micro hardness value is greater than the base sample so it can be used as a raw

material component machining.

1 INTRODUCTION

The results of research published by the German

Federal Ministry of Research and Technology

reported that the loss was economically due to

abrasion and material wear of more than 10 billion

DM and this figure is close to 1% of the state's

budget (Walter, 1981

). Every year large economic

losses are also experienced by some industries

caused by corrosion and wear damage to machinery

and its components. The condition triggers the

demand for improved surface performance of

metallic materials whose impact has brought about

advancements in the field of surface development

technologies

(Suwattananon, 2005).

The role of the surface of metal material is very

important because it is the part that directly in

contact with the environment. To maintain this role,

efforts should be made to improve the surface

resistance to environmental influences has a longer

lifetime. The damaging effects of the environment

on the surface of metallic materials include wear,

corrosion, oxidation, and collision (

Sugondo, 2010).

In addition to counteracting destructive

environmental influences, the role of metal surfaces

can also be increased so as to have added value and

their usefulness can be extended to other areas.

Carbon steel metal material has been widely

used in various components in the fields of industry,

agriculture, machinery, and automotive (Bintang,

2005). The metal has advantages and disadvantages.

Based on carbon composition, carbon steel can be

grouped into several parts, including low carbon

steel with carbon composition of 0.08 to 0.35%,

medium carbon steel with carbon composition 0.35

to 0.50%, and high carbon steel with composition

carbon 09.55 to 1.70% (Smallman, 1999).

Low carbon steel has several advantages,

including strong and ductile, easy to do with

machining, easy to shape, easy to weld, cheap price,

and many available in the market. In addition, low

carbon steels also have disadvantages such as

relatively low hardness, low wear resistance, no

resistance to corrosion attacks, and easilyoxidized so

that pearlite phase decomposition occurs at high

temperatures

(Bintang, 2005).

Sutrisno, ., Budiono, A. and Zera, T.

Technology of Iron Hardening by using the Pressure and Heating Technique.

DOI: 10.5220/0009928729452951

In Proceedings of the 1st International Conference on Recent Innovations (ICRI 2018), pages 2945-2951

ISBN: 978-989-758-458-9

2945

The surface hardening can be performed on low

carbon steels so that the material obtained has a

higher hardness when compared to the hardness of

the original material but remains strong and ductile.

In the process of increasing the hardness occurs

phase changes on the surface of low carbon steel,

whereas in the basic material structure does not

occur changing the phase (Bintang, 2005) .

There are many methods that can be used to

improve the surface performance of metallic

materials as a result of surface development

technologies. In general the method can be done in

two ways. First, the method does not alter the

chemical composition of a base material called

thermal heat treatment, such as the flame hardening

and induction hardening methods. Second, the way

is done by changing the chemical composition of the

base material called thermochemical heat treatment,

for example carburization method, nitriding,

carbonitriding, and boronizing (Bintang, 2005). This

second way is mostly done in the industrial world at

a certain temperature so known as thermochemical

treatment (Roumiana, 2008).

Among the four methods mentioned

above,boronization is the most superior method

because it can provide better results on the surface

performance of metallic materials (Anil Kumar

Sinha, 1990). Boronization is a thermochemical

process in surface hardening that can be applied to a

variety of metal materials, both ferrous and non-

ferrous metals. Boronization methods on the surface

of metallic materials are generally carried out at

temperatures of 700

C up to 1000

C for 1 to 12

hours and can be carried out in solid, liquid, and gas

media (Anil Kumar Sinha, 1990).

As a result of the process of boronization on low

carbon steel will form a layer of boride iron with the

possibility of a single phase FeB, Fe

B, or FeB and

B combined phases (Gopalakrisnan, 2001). The

formation of single phase both FeB and Fe

B is

more desirable because it will produce better

mechanical properties than the combined phases. In

addition, other constituent elements in low carbon

steel alloys also have the possibility to form a boride

phase so the other phases (Setiawan, 2010) will

occur.

The method of boronization is done by

minimizing oxygen technique to avoid the formation

of oxide compounds that can inhibit diffusion

process and reduce the reactivity between iron and

boron (Martini, 2004). The technique is usually

performed by creating an inert gas condition with an

argon gas flow, or it can also be done by making a

vacuum during heat treatment (Martini, 2004). In

addition it can also be carried out under atmospheric

pressure conditions during heating.

Roumiana et al in 2008 has carried out

boronization of powder on low carbon steel AISI

1018 with a mixture of B

C and KBF

powders. The

heating process was carried out at 850° C for 4 hours

under argon gas conditions and resulted FeB and

B borate layers with 75 to 80 μmthickness and

2250 HK hardness. The same study has also been

done by Sugondo in 2007 on St37 steel resulted

FeB and Fe

B borate layers with hardness reaching

1400 HV (Sugondo, 2010).

Boronization methods under vacuum have been

performed by Martini et al in 2004 at 99.9% pure

iron with different powders B

C, SiC, and KBF

compositions. The sample heating was carried out at

850

C for 15 hoursformedFeB and Fe

B using 3

different composition types for B

C powder 10%,

100%, and 90% weight (Martini, 2004). Then in

2006 with the same technique Dybkov et al do

boronization on iron alloy 25% Cr resulted FeB and

Fe2B borate layers using mixed powders B

C and

KBF

. The micro hardness that occurs in the boride

layer is 18 Gpa (Dyvkov, 2006). Both inert gas and

vacuum engineering need the high cost and difficult

to do in a business-oriented industry because of its

less practical use.

To overcome these conditions need to find a

solution so that the heating technique can be done

simply and the implementation is more practical

without reducing the quality of the expected

results.In this research will be applied the pressure

and heating technique with a certain pressure on

boronization powder during the heating process

without reducing the quality of expected results. As

the basic material selected S45C low carbon steel

which is cheap and easily available in the market.

Neither the first method involves altering the

chemical composition of the base material nor the

second way by changing the chemical composition

of the base material, all by a vacuum or by an inert

gas stream. If the equipment is not good then

leakage will often occur so that the hardening

process on the sample that is scientifically

manifested in the form / phenomenon of diffusion

can not take place. Both inert gas engineering and

vacuum engineering both cost considerable and

difficult to do in a business-oriented industry

because of its less practical use.

2 RESEARCH METHOD

The basic materials used as the basic samples are

iron S45C. Iron S45C consists of elements 0.42 -

ICRI 2018 - International Conference Recent Innovation

2946

0.48 wt% C, 0.15 - 0.45 wt% Si, 0.60 to 0.90 Mn,

0.03 P, and 0.035 S (Setiawan, 2010). To know the

mechanicalproperties of the sample before

boronizing, sample characterized by XRF, XRD,

and micro hardness testing. The surface of the

sample to be diboronized first cleaned from the

impurity layer and smoothed in order to obtain

maximum results.



Figure 1. Basic sample of soft iron type S45C



The composition of the powder mixture used

includes 50wt% B

C, 5wt% KBF

, and 45wt% SiC.

The mixed powder is inserted into the iron base

sample S45C, and pressed with a pressure of 15 tons

and then heated in a furnace with a temperature of

700, 800, and 900

C for 8 hour heating time.A

container containing a working sample that has been

sealed with a boron powder is fed into the furnace to

be heated. Figure 2 shows the container that has

contained the working sample put in the furnace and

is ready to be heated.





a



b



Technology of Iron Hardening by using the Pressure and Heating Technique

2947



Figure 2. The sample into cylinder and lead (a), boriding

powder covered the sample (b), cylindrical container

claimed by pressure (c) container in the furnace is heated.

By applying pressure to the boronization

powder, the heating of the container in the furnace is

carried out directly without using a vacuum system

or draining the argon gas into the furnace.The

heating setting begins by raising the heating

temperature from room temperature to 700°C within

30 minutes. After reaching the temperature 700°C

held for 8 hours. This process is carried out also for

temperature of 800 and 900

C during 8 hours . When

finished the heater is stopped and the cooling is done

naturally at room temperature.

If it has been shown room temperature, the

boronized treated work sample is removed from the

heater.To find out the changes, the already

boronized sample is characterized and tested.

Characterization was carried out to find out the

change of micro structure, whereas the test was

performed to see micro hardness at the cross section

of the boride layer. The diffraction pattern of the

obtained XRD data was analyzed using GSAS to

determine the phase composition of the boride layer.

In a sample that has been boronized observations

of microstructure to see the morphology of the

boride layer formed. The observations use a Nikon

optical microscope with 200 times magnification.

The depth of the boronized borate layer is obtained

from the average depth of sawtooth (Setiawan,

2010). All of the boronized samples were tested for

hardness using a LeitzMiniload test kit with a 5 kg

load. The indenter used is Vikers type. The vertical

pyramid indicator angle is 136 °. Giving style is

done slowly without collision. When touching the

indenter is held for 10 to 15 seconds. Styles are

given according to the load mounted on the test

equipment. After the force is removed, the track of

the indenter on the sample is measured. The material

hardness is calculated by equation (Setiawan, 2010):

Figure 3. The Vickers Hardness Instrument

Figure 4. The Vikers identor Leitz Miniload

HV = vikers micro hardness;

d = average identor spell;

P = given force

Micro hardness testing is performed on two

different points to see the gradationhardness of the

boride layer. The assumption in this test is at a

certain depth of valuethe violence is the same.To

determine the diffraction pattern and the atomic

position in the molecule the samplecharacterized by

XRD. From the obtained diffraction pattern can be

calculated size of crystallites (particle size). The

crystallite size can be calculated using the Debye

equation Scherrer as follows (Setiawan, 2010):



4.1854)2/sin(2000

HV 

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





CosL

hkl

Where:

K : form factor, was 0.9 for ball shape.



: X-ray wavelength (Å).

hkl

: FWHM (rad)

hkl

: crystal size (Å)



: diffraction angle.

3 RESULT AND DISCUSSION

The basic material samples performed by initial

characterization are S45C which is a soft iron or

low carbon alloy steel. Both samples characterized

using XRF (X-ray flourence) to determine the

composition elements in the material and XRD to

know the phases and crystal structures. The

boronization powder used in this study is B4C,

SiC, and KBF

. After that the three powders are

mixed with each other so that obtained

boronizingpowder ready to use. The steps of

execution of sample characterization and

boronization powder are as follows.

Table 1. The composition in Steel S45C

Element C Si Mn P

S45C 0.45% 0.30% 0.6-0.9% 0.03%



Figure 5. XRD data of iron sample on the temperature of

700, 800, and 900



b



Figure 6. View of boridedcross-sections treated at

(a)700

C, (b) 800

C, and (c) 900oC for 8 hours with

powder pack boriding thickness.

FeB

Fe2B

diffusion zone

Technology of Iron Hardening by using the Pressure and Heating Technique

2949



a



b



Figure 7. The hardness of iron S45C (a) before treatment

(b) after treatment

The results of characterization with XRD for the

S45C iron samples indicate Fe iron phases at certain

angles (figures 4). While the results of

characterization with XRF written in table 1 also

indicated the composition of carbon elements with

low concentration. This suggests that the S45C iron

samples are low carbon steels which are often used

as samples on the engineering of metal surface

hardening.

In order to obtain better results in the surface

hardening of the S45C iron samples, it is necessary

to minimize the particle size of the boronized

powder particles which will serve as the raw

material for metal hardening. The size of the particle

diameter can be obtained by milling (piercing) the

boronization powder within 10 hours. Boronized

powder is inserted into tubes containing iron balls of

different diameter sizes. Tubes that already contain

iron balls and boronisasi powder then vibrated or

rotated with a certain speed and time. From the

results of the milling obtained a decrease in particle

diameter size from 8.374 micron to 0.6885 micron

boronized powder.

The comparison of hardness S45C iron samples

between before and after boronization has increased.

The hardness on the iron surface S45C was 125 HV

before treatment and after boronization the hardness

increased to 887 HV.

4 CONCLUSION

From the sample preparation and characterization

results temporarily, it can be concluded:

1. With heating and pressure technologies applied to

powder boronization hardening methods can

increase the surface hardness of iron samples

S45C from 125 HV to 887 HV.

2. In terms of research operational costs, heating and

pressure techniques can save up to 60% when

compared to vacuum or argon gas drainage

techniques

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Karakterisasi Material Baja Karbon Rendah Hasil

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