**6. References**


**Part 2** 

**Welding of Aluminium Alloys** 

60 Recent Trends in Processing and Degradation of Aluminium Alloys

RD-ECAP. In the case of Al-23 mass% Si alloy, absorbed energy of a sample processed 32 passes was about 18 times higher than that of a sample processed 0 pass. In the case of Si-whisker/extra super duralumin composite, after pressing by RD-ECAP for 10 passes, grain size was 1.5-2 μm and Si-whisker distribution became homogeneous. Also, Mg alloys and titanium processed by RD-ECAP were studied and the results confirmed that RD-ECAP

A new ECAP processing method called rotary-die equal channel angular pressing (RD-ECAP) was developed at Japan's National Institute of Advanced Industrial Science and Technology (AIST, formerly the National Industrial Research Institute of Nagoya (NIRIN)), to form fine-grained bulk materials such as aluminum alloys, aluminum composites,

1. ECAP processing of up to 32 passes (one pass=one extrusion) can be done without

4. Over 30 cycles (one cycle=one extrusion and 90° die rotation) of processing were

Researches on aluminium processing by ECAP deformation of more than 20 passes are still very few in the world. Therefore, other excellent effects or features are expected to be

The author thanks Dr. Yoshinori Nishida and Dr. Aibin Ma for his advice and material offer.

Y.H. Zhao, Y.T. Zhu, X.Z. Liao, Z. Horita and T.G.Langdon: *Mater. Sci. Eng*. Vol. A463

Y. Nishida, H. Arima, J.C. Kim and T. Ando: *J. Japan Inst. Light Metals*. Vol. 50-12 (2000), p.

Y. Nishida, H. Arima, J.C. Kim and T. Ando: *J. Japan Inst. Metals*. Vol. 64-12 (2000), p. 1224-

A. Ma, K. Suzuki, N. Saito, Y. Nishida, M. Takagi, I. Shigematsu, H. Iwata: *Mater. Sci. Eng*. *A*,

A. Ma , K. Suzuki, Y. Nishida, N. Saito, I. Shigematsu, M. Takagi, H. Iwata, A. Watazu, T.

A. Watazu, I. Shigematsu, A. Ma, K. Suzuki, T. Imai, N. Saito: *Mater. Trans*. Vol. 46 (2005),

A. Watazu, I. Shigematsu, X. Huang, K. Suzuki and N. Saito: *Mater. Sci. Forum* Vol. 544

R.Z. Valiev, A.V. Korznikove and R.R. Mulyukov: *Mater. Sci. Eng*. Vol. 168 (1993), p. 141. V.M. Segal, V.I. Rexnikov, A.E. Drobysevsky and V.I. Kopylov: *Metally* Vol. 1 (1981), p. 115. S.L. Semiatin, V.M. Segal, R.E. Goforth, N.D. Frey and D.P. Delo: *Metall. Mater. Trans*. *A,* Vol.

5. Aluminium material with fine grain and high impact toughness can be formed.

is useful for forming fine-grained light metal materials.

3. One-pass RD-ECAP can be processed in 30 s.

magnesium alloy, and titanium. RD-ECAP has the following features:

2. RD-ECAP saves energy because there is no cooling and re-heating.

**4. Conclusion** 

sample removal.

discovered in the future.

**5. Acknowledgment** 

**6. References** 

possible in a short time.

(2007), p. 22-26.

30A (1999), p. 1425.

Vol. 399 (2005), p. 181-189.

Imura: *Acta Materialia* Vol. 53 (2005) , p. 211.

655-659.in Jp.

1229.in Jp.

p. 2098.

(2007), p. 419.

**4** 

*México* 

**Welding of Aluminum Alloys** 

*Cerrada de Cecati S/N Col. Sta. Catarina C.P. 02250, Azcapotzalco, DF,* 

Welding processes are essential for the manufacture of a wide variety of products, such as: frames, pressure vessels, automotive components and any product which have to be produced by welding. However, welding operations are generally expensive, require a considerable investment of time and they have to establish the appropriate welding conditions, in order to obtain an appropriate performance of the welded joint. There are a lot of welding processes, which are employed as a function of the material, the geometric characteristics of the materials, the grade of sanity desired and the application type (manual, semi-automatic or automatic). The following describes some of the most widely used

This is a welding process that melts and joins metals by means of heat. The heat is produced by an electric arc generated by the electrode and the materials. The stability of the arc is obtained by means of a distance between the electrode and the material, named *stick welding*. Figure 1 shows a schematic representation of the process. The electrode-holder is connected to one terminal of the power source by a welding cable. A second cable is connected to the other terminal, as is presented in Figure 1a. Depending on the connection, is possible to obtain a direct polarity (Direct Current Electrode Negative, DCEN) or reverse polarity (Direct Current Electrode Positive, DCEP). The core wire of the coated electrode conducts

The heat of the arc melts the wire core and the coating (flux) at the tip of the electrode. The melt material is transferring to the base metal in a drop shape, as is showed in Figure 1b. The molten metal is stored in a weld pool and it solidifies in the base metal. The flux due to its low density floats to the surface of the weld pool and solidifies as a layer of slag in the

The electrode covering contents some chemical compounds, which are intended to protect, deoxidize, stabilize the arc and add alloy elements. There are basically four types of electrode coating types: (i) *Cellulosic* (20-60% rutile, 10-20% cellulose, 15-30% quartz, 0-15% carbonates, 5-10% ferromanganese), which promotes gas shielding protection in the arc region, a deep penetration and fast cooling weld. (ii) *Rutile* ( 40-60% rutile, 15-20% quartz, 0- 15% carbonates, 10-14% ferromanganese, 0-5% organics), this is employed to form slags mainly for slag shielding, it presents high inclusion content in weld deposit. (iii) *Acid* (iron

the electric current and it provides filler metal to perform the weld.

**1. Introduction** 

welding process for aluminum alloys.

surface of the weld metal.

**1.1 Shielded metal arc welding (SMAW)** 

R.R. Ambriz and V. Mayagoitia *Instituto Politécnico Nacional CIITEC-IPN,* 
