STUDY ON ELASTIC - PLASTIC BEHAVIOUR OF EN 43 B (AISI … · In this paper work, the experimental...

STUDY ON ELASTIC- PLASTIC BEHAVIOUR OF EN 43 B (AISI 1042) HSLA

STEEL Chandan Kumar

1, Samrat Majumdar

2, Rituparna Biswas

2, G.Ragul

2*, Prasidh E Prakash

3,

Dehesinghraja J4

1

Department of Civil Engineering, Budge Budge Institute of Technology, Kolkata, India 2

Department of Mechanical Engineering, Budge Budge Institute of Technology, Kolkata, India 3

Department of Mechanical Engineering, Malabar College of Engineering and Technology, Kerala, Ind ia 4

Department of Management & Fashion Technology, DC School of Management & Technology, India *[email protected]

Abstract

In this paper work, the experimental research of behaviour of high-strength low-alloy steel (HSLA) exposed to low-cycle fatigue (LCF) with controlled and tested in EN 43 B (AISI 1042) grade steel. At the different stage the characterization and description of low cycle

fatigue of Elasto-plastic behaviour of material was thoroughly investigated. According to ASTM standard computerized UTM, Impact test and hardness test were conducted at three

orientations that is Long Side-Short Side (L-S) Long Side-Transverse Side (L-T) and Transverse Side-Short Side. In this research work the effects of low cycle fatigue of crystallographic texture and micro structure on elastic modulus of EN 43B steel have been

investigated in Scanning Electron Microscope (SEM). By this parameters can be used to predict their life, service and operational safety at different conditions.

Keywords: HSLA, Low Cycle fatigue, Elastic Modulus, Micro structure, Texture.

1. Introduction

The mechanical behaviour like elasticity, plasticity are very much important for the designs

manufacture and maintenance of machine elements and structures. Elastic-plastic behaviour of welded joints during loading and unloading of pressure vessel has been analyzed where two stage

pressuring process has been applied investigation and the effect of residual stress and strain has been analyzed. Liang Dai. et.al, [1] studied the influence of damage on time-dependent spring

back for U-shaped HSLA steel plate, Sedmak et.al [2] analysed the effect of residual stress and strain in the low cycle fatigue, S. Pramanik et.al, [3] studied the effects of crystallographic

texture and microstructure on the elastic modulus of different grades of steel have been expressing both the fundamental and the practical aspects of the different grades of steel used for various purposes, V.Aleksić et.al, [4] has discussed about static and dynamic, that is

monotonous and fatigue behaviour of steel NN-70 exposed to the effects of low- cycle fatigue, i.e. monotonous and fatigue behaviour of the material. High strength low alloy

(HSLA) steel pipes such as API-X80 and beyond, have found increasing applications in deep offshore hydrocarbon development projects in the study conducted by [5] M.Talebi et.al. Effects of parameters such as the exposure duration, corrosion morphology and loading

International Journal of Pure and Applied MathematicsVolume 119 No. 12 2018, 15801-15811ISSN: 1314-3395 (on-line version)url: http://www.ijpam.euSpecial Issue ijpam.eu

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conditions on the monotonic response, cyclic response, and local deformation mode, number of cycles to failure and modes of failure were examined. The cyclic elasto-plastic

deformation and fatigue failure properties of API-5L X65 steel was characterized under monotonic, high cycle fatigue, strain controlled low cycle fatigue, and stress controlled

ratcheting loading regimes by Oluse gun et.al [6]. And also concluded by the study that low cycle fatigue lifetime decreased with increase in total strain amplitude and plastic strain amplitude[7]. It is shown that, under uniaxial fully reversed loading.

2. Material Selection and Metallographic specification of EN 43 B steel

The material studied in current investigation is an HSLA steel, this material is also called as spring steel which is having widely used in automobile and piping industries. Metallographic

Specimen preparation and examination for metallographic examination purpose small piece of

approximately 12mm×12mm×10mm size were cut with the help of a hacksaw from the as-received material. The sample so cut is grinded by wheel, belt grinders and various grades of

silicon carbide abrasive papers (emery papers). The specimen subsequently polished on velvet

cloth using diamond paste of particle size of 1µm ~0.25µm. The metallographic specimen subsequently etched with freshly prepared 2%Nital solution. To examine the microstructure of as-

received material, well etched metallographic specimens of the material were prepared in three

directions: L-T, L-S, and T-S. Then they were examined in all three directions with the help of an optical microscope (Carl Zeiss Microscopy).

The chemical composition is provided in Table.1 Table. 1 Chemical composition of the HSLA steel

Chemical Composition

Carbon 0.45

Magnesium 0.57

Silicon 0.25

Phosphorus 0.035

Sulphur 0.036

Aluminum 0.12

Vanadium 0.001

Molybdenum 0.001

Iron Balance

3. Hardness evaluation

3.1 Rockwell hardness evaluation

Rockwell hardness testing machine is used to evaluate the hardness. For this purpose a

specimen of approximately 40mm×20mm×20mm size were cut with the help of a hand saw. The hardness is examined in three directions L-T, L-S, T-S. Rockwell hardness evaluation procedure with 3 times on the specimen by selecting different

points in the specimen. Rockwell hardness values were measured in all three perpendicular direction (L-T, L-S and T-S).

Material of specimen = Medium carbon steel Indenter used = conical diameter=1.568mm Initial load =10kg.f =10*9.81= 98.1N

Table. 2 Rockwell hardness value in L-T Direction

Material Trail No Rockwell hardness

value

Average hardness

value

EN 43B Steel

1 80 73.66 2 73

3 68

International Journal of Pure and Applied Mathematics Special Issue

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Table. 3 Rockwell hardness value in L-S Direction


value

Average hardness

value

EN 43B Steel

1 60 62.66 2 62

3 66

Table. 4 Rockwell hardness value in T-S Direction


value

Average hardness

value

EN 43B Steel

1 63 63 2 65

3 61

3.2 Brinell hardness evaluation

Brinell hardness testing machine were used here to find the hardness. For this a specimen of approximately 40mm×20mm×20mm size were cut with the help of a hand saw. The hardness

is examined in three directions L-T, L-S, T-S. However test load should be kept equal to 30 times the square of the diameter of the ball. Apply load for a minute of 15 sec to 30 sec and

remove the load and measure diameter of indentation nearest of .02 using microscope 1. Calculate the Brinell hardness number (1+BN) as per (500) 2. Brinell number 2F/3.14(D-(D-d)); d= diameter of the ball intention.

3. Brinell hardness number can be obtain from Table.5-7 Table. 5 Brinell hardness value in L-T Direction

Load Diameter 1 Diameter 2 Mean diameter BHN

1 2

1000 10 1.2 1.3 1.25 811.67

2000 10 1.9 1.8 1.85 737.62

3000 10 2.5 2.4 2.45 626.66

Table.6 Brinell hardness value in L-S Direction


1 2

1000 10 1.4 1.32 1.36 685.19

2000 10 2.2 2.34 2.28 474.92

3000 10 3.2 3.4 3.3 414.64

Table.7 Brinell hardness value in T-S Direction


1 2

1000 10 1.0 1.1 1.3 793.46

2000 10 1.8 1.9 1.85 779.53

3000 10 2.5 2.55 2.53 601.45

Calculations of Brinell hardness number is follows:

I n L-T direction

1. Brinell number = 2F/

= 2*1000/


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=811.67BHN

2. Brinell number = 2*2000/ )

=737.62BHN

3. Brinell number = 2*3000/

=626.66 BHN Mean Brinell hardness number: 725.31 BHN

In L-S Direction


= 2*1000/

=685.19 BHN


=737.62 BHN


=601.45 BHN Mean Brinell hardness number: 674.75 BHN

In T-S Direction


= 2*1000/

=793.46BHN


=737.62BHN


=601.45BHN Mean Brinell hardness number: 710.84 BHN

4. Low Cycle fatigue testing by computerised UTM Tensile tests are performed on round bar specimens of diameter 20 mm and gauge length 300

mm out of the as received material. The tests were conducted following the ASTM standard E8-M [37]. The nominal dimensions of the tensile specimens were a 30cm length and 2cm diameter rod.

All tests were carried out with the help of a 100kN servo-hydraulic Universal Testing Machine connected with computer that is running Windows based monotonic application

software supplied by BiSS. The software has facility for controlling the test control parameters, like strain rate, cross head speed and data acquisition system on load, displacement and extensometer in the channels. During test using a 25 mm gauge length

extensometer at room temperature, carried out at a displacement rate 1 mm/min. The true strain was measured through 25mm gauge length extensometer, mounted to the mid-section

of the specimen length. The tensile test generated data after test were investigated to estimate the various mechanical properties of the material.


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Fig 1. Photographic view of Computerized 100 KN servo UTM

5. Charpy impact toughness test

Charpy impact toughness test were conducted on Indian standard specimen with dimension 10mmX10mm square cross section with 55mm length, provided 5 mm deep U-notch notched

at one side at mid-point of its length. Charpy impact energy and impact toughness are determined by the following relationship as: Impact strength =Energy absorbed/cross sectional area at the break point.

From charpy impact test the toughness of the specimen can be determined at the atmospheric temperature. The impact strength and modulus were calculated.

Table. 8 Impact strength and impact modulus values

S. No Area of specimen

( )

Impact energy

(Joules)

Impact strength

(J/ )

Impact modulus

(J/ )

1 10*10=100 300-80=220 220/100=2.2 220/5500=0.04

Calculations:

Area of cross section = 10*10 =100

Volume of specimen = 10*10*55 = 5500

Impact strength = = = 2.2 J/

Impact modulus = = =0.04 J/

6. RESULTS AND DISCUSSION

The various mechanical properties are determined by various tests. Different test results from various tests conducted are tabulated in this section and also analysed it. The test results from

tensile test, Hardness tests, Charpy impact test are described in this section. Also SEM results are analysed. Tensile test result are shown in Table 9.

Table 9. Tensile test result by UTM

Input Data Output Data

Specimen Shape Solid round Load at yield 130.10 KN


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Specimen Type Mild Steel Elongation at yield 24.500 mm

Specimen Description EN 43B Yield stress 414.120 N/mm2

Specimen Diameter 20 mm Load at peak 206.50 kN

Gauge Length for % Elongation 150 mm Elongation at peak 55.100 mm

Pre Load Value 0 N Tensile Strength 657.308 N/mm2

Max. Load 1000 KN Load at break 12.50 kN

Max. Elongation 250 mm Elongation at break 64.400 mm

Specimen CS. Area 314.16 mm2 % Elongation 20.13%

% Reduction area 32.35%

6.1 SEM analysis

Well-polished and etched metallographic specimens were studied using an optical

microscope (Carl Zeiss Microscopy). The SEM analysis was done in 4 magnifications

Fig 2. SEM analysis in 100x magnification



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6.2 Hardness test result

6.2.1 Rockwell hardness Hardness in L-T Direction: 72.66 RHN

Hardness in L-S Direction: 62.66 RHN Hardness in T-S Direction: 63 RHN

6.2.2 Brinell hardness Hardness in L-T Direction: 725.31 BHN

Hardness in L-S Direction: 674.75 BHN

Hardness in T-S Direction: 710.84 BHN 6.3 Charpy impact test result

The impact strength of the specimen: 2.2 j/

The impact modulus of the specimen: 0.04 j/


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Fig 6. Load v/s cross head travel graph

Fig 7. Load v/s time

Fig 8. Stess v/s cross head level Graph


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Fig 9. Stress v/s strain Graph

7. CONCLUSION

The study elastic plastic behaviour of HSLA steel was done and we arrived the

following conclusions. This material can be used in the heat treated condition for a great

variety of components in vehicles and for general engineering were low mechanical

properties and small sections of the heat treated articles are involved. And also can be applied

for parts subject wear in the normalized state, break, camshafts, axles, spring bolts, roller

bearing for bridges, gear driving wedges etc.

The experiments on dual-phase steel subjected to strain-path changes

demonstrate that pre-straining primarily affects the elastic-plastic transition during the early

stage of reloading. The transient behaviour is strongly dependent on the orientation of

reloading, with the largest effect being in the transverse direction. However, the material

exhibits a fading memory of the strain-path change with subsequent plastic straining, which

may indicate that the transient anisotropic behaviour is expected to be the presence of

residual phase stresses. The residual phase stresses are believed to increase rapidly at small

pre-strains but saturate at large pre-strains in dual-phase steels. This is further substantiated

by measurements of plastic strain ratios (Rα) and flow stress ratios (rα) in the transient stage

and later stages. Significant flow and strength anisotropy is seen in the transient stage but it

fades away at larger strains in the reloading direction. The results from the pre-strained

material indicate that non-linear isotropic hardening is insufficient to represent the material

behaviour covering monotonic, 45◦ tensile path changes and orthogonal tensile path changes.

Therefore, the transient effects on the stress–strain behaviour under strain-path changes are


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modelled using a high exponent yield surface and combined non-linear isotropic and

kinematic hardening. The identification method used in this paper evaluates the back stresses

from simple uniaxial tensile tests and numerical testing. The simulations are able to predict

the stress–strain behaviour with acceptable accuracy at all pre-strains, and most importantly

the general trends of the experimental results are captured to a great extent. However, the

simulations show some discrepancy in predicting the stress–strain behaviour after 8% pre-

strain. Furthermore, the model is not able to accurately describe the transient, deformation-

induced anisotropy in the plastic flow subsequent to the strain path change. There is

accordingly potential for improvements of the constitutive model and the associated

identification method. The range of validity of the model to various stress-states, such as

tensile-shear and tensile

REFERENCES

[1] Liang Dai, Hao-Jie Jiang, Ting Dai, Wei-Li Xu, Ai-Hui Luo, “Investigation on the

influence of damage to spring back of U-shape HSLA steel plates”, Journal of Alloys and Compounds, Elsevier, Volume 708, Pp. 575-58625, June 2017.

[2] Sedmak, Algool, Sedmak, Tatic, Dzindo, “Elastic plastic behaviour of welded joints during loading and unloading of pressure vessels”, Procedia Structural Integrity, Elsevier,

Vol. 2, 2016, pp. 3546–3553. [3] S. Pramanik, S. Suwas, R. K. Ray, “Influence of crystallographic texture and

microstructure on elastic modulus of steels”, The Canadian Journal of Metallurgy and Materials Science, Taylor & Francis, Vol 53, Issue.3, Pp. 274-281, 2014.

[4] V.Aleksić, Lj.Milović, B.Aleksić, Abubkr M. Hemer, “ Indicators of HSLA steel behavior under low cycle fatigue loading”, Procedia Structural Integrity, Elsevier, Vol. 2, Pp

3313-3321, 2016.

[5] M.Talebi, M. Zeinoddini M. Mo'tamedi, A.P. Zandi, “Collapse of HSLA steel pipes under corrosion exposure and uniaxial inelastic cycling”, Journal of Constructional Steel Research, Elsevier, Vol. 144, Pp. 253-269, 2018.

[6] Oluse gun, Fatoba, Robert Akid, “Uniaxial cyclic elasto-plastic deformation and fatigue

failure of API-5L X65 steel under various loading conditions”, Theoretical and Applied Fracture Mechanics, Elsevier, Vol. 94, Pp. 147-159, 2018.

[7] Dr.R.Rameshkumar INVESTIGATION ON PERFORMANCE OF HYBRID FIBRE IN REINFORCED CONCRETE International Journal of Innovations in Scientific and

Engineering Research (IJISER)


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