Memperkirakan Umur Komponen Mesin yang Kritis Berdasar Laju Perambatan Retak.

Kata kunci: Umur Komponen Mesin - Perambatan Retak

Pengaruh Perlakuan Panas Terhadap Laju Perambatan Retak Fatik Baja Tahan Karat Aisi 304

The effect of a local heating due to a joint weld on the fatigue crack growth of the stainless steel AISI 304 has been investigated. The test was performed in a room temperature condition with a constant load amplitude and the load ratio was maintained to be 0.3. The load frequency was adjusted from 5 to 15 Hz depending on the performance of the testing machine used. Center cracked specimens were used\u27in this research and the initial crack was introduced by using EDM (Electro Discharge Machining). Those specimens were subsequently tested on the Shimadzu closed loop servo hydraulic testing machine and the increment of the crack length was monitored using two traveling microscopes. The results show that the effect of the local heating around the cracktip can reasonably increase, whereas the annealing process can decrease the fatigue crack growth rates. The observation on the microstructures shows that the size of crystal grains increase significantly after the annealing process

Perbandingan Laju Perambatan Retak AL 2024-T3 dan AL 2524-T3 Setelah Mengalami Perlakuan Permukaan.

The objective of this research is to compare the mechanical properties and crack growth rates between Al 2024-T3 and Al 2524-T after being chemically milled and shotpeened processes. First of all, one side of the aluminum surface was chemically milled using NaOH + Na2S +H20 etchant. The surface was then shotpeened with 0, 03A, 0, 05A and 0, 07A peening intensity. The product of chemical milling and shotpeening was tested its hardness, roughness, tensile and crack growth rates. The crack growth test was carried out using a servo hydraulic MTS 810 testing machine under stress level 20% and R= 0,3. The extension of crack length was monitored using two travelling microscopes. Experimental result shows that the fatigue life of chemical milling product decreases about 32% and 22% compared to that of raw materials for Al 2524-T3 and Al 2024-T3, respectively. On the other hand, the fatigue life of shotpeening product increase varying from 85% to 105% compared to that of raw materials. In general, The chemical milling product of Al 2024-T3 has better fatigue life compared to that of Al 2524-T3. In contrast, The shotpeening product of Al 2524-T3 has better fatigue life compared to that of Al 2024-T3. Keywords : chemical milling, shotpeening, crack growth rat

Analisis Pengaruh Retak Terhadap Ketangguhan Baja Karbon Rendah Dengan Parameter Integral J

The material toughness test using a J-integral parameter has been carried out using two methods, namely direct method and unloading method. Calculation of Jic was performed based on yield point, first load drop, initial crack growth and fracture criteria. The J-integral parameter obtained from experimental results was then compared with stress intensity factor (K) for the same material. The stress intensity factor test was carried out in accordance with the ASTM E-399 procedures. The type of specimen for both J-integral and stress intensity factor was compact tension specimen (CTS) with three different thickness, namely 13,5 mm, 20,0 mm and 23,0 mm. The measurement results give the average value of stress intensity factor, Kc = 147,01 kg/min", 185,67 kg/inin\u27f2 and 207,38 kg/mre2 for the thickness of 13,5 mm, 20,0 mm and 23,0 mm, respectively, In addition, the average value of .1- integral parameter is 11,32 kg/mm. The value of .1-integral for the specimen with different thickness is relatively the same. Therefore, this parameter provides an alternative solution to determine the toughness of low carbon stee

The Effect Of Chemical Milling On The

ABSTRACT The effect of the chemically milled surface of aluminum alloy Al 2024-T3 on the characteristic of fatigue crack growth rate\u27 has been investigated The effect of a single overload has also been studied. The test was carried out under, sinusoidal loads with firstly constant amplitude at the stress ratio (R) of 0.3. and 0.6. Secondly, similar to the first test, however, it was followed by a , single tension overload with- the _overload ratio (OLR) of .1.5 anc1 2.0. Application of the overload, was conducted manually at static load after the crack propagated approximately 4.0 mm length.. The experimental result shows that the chemically milled surface specimen has slightly higher the fatigue crack growth rate for higher stress ratio. However, the effect of chemical milling becomes more significant for lower stress ratio. The existence of a single overload can delay crack growth, andthe increase of the overload ratio can significantly decrease the crack growth rate. Key words: Crack growth, fatigue, aluminum allay, overload ,

Kekuatan Tarik Paduan Al 2024-T3 Dan Al 2524-T3 Yang Telah Mengalami Proses Stretching, Chemical Milling Dan Shot Peening

AbstrakPenelitian ini bertujuan untuk mengetahui perilaku uji tarik produk Al 2524-T3 dan Al 2024-T3 yang mengalami proses peregangan, chemical milling dan shot peening. Paduan ini diregangkan melebihi tegangan yeildnya masing-masing 1%, 3% dan 5%, kemudian dilakukan proses chemical milling satu sisi. Etsa yang digunakan dalam proses milling kimia adalah larutan NaOH + Na2S + H2O dengan konsentrasi tertentu. Pada permukaan dilakukan proses shot peening dengan variasi intensitas masing-masing 0,03 A, 0,05 A dan 0,07 A. Material tersebut kemudian diuji sifat mekaniknya dengan uji tarik. Hasil penelitian menunjukkan bahwa tegangan ultimate dan tegangan yield material meningkat dengan meningkatnya persentase regangan. Namun, perpanjangan juga meningkat yang menunjukkan bahwa proses peregangan justru meningkatkan keuletan. Di sisi lain, proses shot peening menurunkan elongasi yang mengindikasikan bahwa proses shot peening menyebabkan penurunan keuletan material. Kata kunci: pengujian tarik, chemical milling, shot peening, stretchingAbstractThis study aims to investigate the tensile test behaviour of Al 2524-T3 and Al 2024-T3 product, which undergoes stretching, chemical milling and shot peening processes. These alloys were stretched beyond yield stress, namely 1%, 3% and 5% of each, and then performed chemical milling process of one side. The etching used in chemical milling process were NaOH+Na2S+H2O solutions with certain concentration. The surface was performed shot peening process with varying intensity of 0.03 A, 0.05 A and 0.07 A respectively. The material then tested its mechanical properties by tensile test. The results show that ultimate and yield stress of material increases with the increase of stretching percentage. However, the elongation has also increased which indicates that stretching process actually increases the ductility. On the other hand, the shot peening process decreases the elongation which indicates that the shot peening process causes a reduction in the ductility of the material.  Keywords: tensile tes, chemical milling, shot peening, stretchin

Karakteristik lelah poros baja S45C bertakik V akibat beban amplitudo konstan dan beban tiba-tiba.

This study aims to investigate the effects of sudden loads on the fatigue characteristic 60° V-notched shaft of S45C steel under constant and sudden amplitude loads, and to identify the fracture surface. The fatigue tests were performed using rotary bending machine that was equipped by the sudden load equipment. The cyclic load was varied in three configurations, i.e constant amplitude load and two combination of sudden loads. The combination of sudden loads were designed with 84 and 52 cycles ON and OF periodically. The sudden load causes the stress increase to 76 MPa. The stress concentration factor on the V.. notched shaft was determined using finite element model. The S-N curve of three load configurations shows that stress amplitude of 154 MPa (35% a,. or 21% au), 108 MPa (25% o or 15% au) and 28 MPa (6% ay or 4% au) cause the materials fail above 1,6.106 cycles. In that cycle, the value of stress amplitude under combination loads decreases 70,13% and 18,18% compared to constant amplitude load. The fracture surfaces under sudden load have rougher and more brilliance of beach mark. Similarly, the failures under higher stress have rougher fracture surface

Pengaruh Pengerasan Regangan Terhadap Ketangguhan Baja Grade B

ABSTRACT The objective of this research is to invesrigate the strain hardening effects on the fracture tougness of plates grade B. A number of plates, which has been done cooled forging, was cut to produce CTS specimens. Fracture toughness speciment was conducted in accordance with ASTM standard E399-83. The test results show that the fracture toughness of steel plate is 76 MPalim. The fracture toughness of strain hardened plate is slightly higher than fracture toughness of base steel plate

Perilaku Laju Perambatan Retak Fatik Pada Hasil Pengelasan Tig Al 6061 â T4

ABSTRAK Fatigue crack growth rate of T1G welding joint of Al 6061 â T4 has been investigated. The tests were performed in a room temperature with a constant load amplitude and the load ratio was maintained to be 0,1. The load frequency was adjusted in the range of / â I 1 Hz. Crack propagation tests were carried out on 1.6 mm thick of center crack tension (CO) specimens with longitudinal and transversal bun joints. Alternating current manual TIG welding has been set in 5 nmvs traveling speed, 10 volt, 60 A current, with 1,6 mm filler diameter. The filler wire used in this research was Al 4043. The experimental result shows that crack growth rate on HAZ zone of transversal but joint increases the Paris constant\u27s n from 3,43 to 3,7 or about 9 % and C from 6,39 x 10-n to 2,63 x /0 0. Paris constant\u27s n of fatigue crack growth rate on weld zone decreases about 10 %. On longitudinal butt joint crack growth rate, the CGR is increased when the crack tip is acrossing the weld zone. Transversal butt joint reduces the tensile strength of Al 6061 â T4 about 39 % and elongation about 81,5 %. The tensile strength of longitudinal butt joint decreases about 25% Filler\u27s compositions Al 4043 increases composition of Si in the weld zone become 2,27%. Key words. : Aluminum, welding, fatigue crack growth rate

STRUKTUR MIKRO LAS BAJA C-Mn PADA PENGELASAN BUSUR TERENDAM DENGAN VARIASI MASUKAN PANAS (Microstructure of Submerged Arc C-Mn Steel Weld Metals with Variation of Heat Inputs)

ABSTRACT The present investigation aims to study the effect of heat input on the microstructure of submerged arc C-Mn steel weld metals. Specific attention was paid to the formation of acicular ferrite which improved weld mechanical properties. The welding process was carried out using four different heat inputs, namely 3.99 kJ/mm, 3.19 kJ/mm, 2.12 kJ/mm, and 1.77 kJ/mm. Microstructural examinations were performed using optical microscope in combination with scanning electron microscope (SEM) to study the mechanism in which acicular ferrite was performed. Results showed that weld metal with heat input of 2.12 kJ/mm produced weld metal with a large amount of acicular ferrite at the expense of grain boundary ferrite and Widmanstatten ferrite. It is evident that this acicular ferrite nucleates on the inclusions in the forms of Si02, TiO, and Al203. Key words : heat input, acicular ferrite, mechanical propertie