Evaluation of Mechanical and Microstructural Properties of Cast Iron with Effect Of Pre Heat and Post Weld Heat Treatment

Abstract

Most of the welding of cast iron is repair welding. Carbon pickup and resulting cracks are the main concerns when welding CI. The casting process is never perfect, especially when dealing with large components. Instead of scrapping defective castings, they can often be repaired by welding. Naturally, the very high carbon concentration of typical CIs causes difficulties by introducing brittle martensite in the heat-affected zone of weld. It is therefore necessary to preheat to a temperature of 650 °C, followed by slow cooling after welding, to avoid cracking. The welding was carried out with manual shielded metal arc welding using ENiFe-CI filler metal. Shielded metal arc welding process using a nickel electrode was used to join a grey cast iron. The effect of pre heating on the microstructure, hardness, tensile and toughness was studied than the effect of post weld heat treatment (PWHT) on the microstructure, hardness, tensile and toughness was studied after that the same was tested on the preheated and post weld heat treated specimens. After that we concluded that which heat treatment process is suitable for cast iron weld.

The effect of current strength on tensile strength and impact toughness of cast iron welded joints

“…Pearlite is a strong and hard mineral. Tensile test results yielded high values at high current utilization [2][3][4], [7,8], [11], [24]. The microstructure in Figure 4a and Figure 4(b) shows that ferrite and graphite separate in groups, resulting in low strength.…”

“…To achieve satisfactory results when welding cast iron in this condition, specific techniques and processes are required. Methods and process advancements for producing high and tough weld strengths, particularly for cast iron materials, are still desperately needed [2][3][4][5][6][7][8]. A fracture or break in one of the spare parts on the machine made of cast iron at PT Indocali Plast is a common occurrence, and it requires immediate repair so that the production process is not delayed.…”

“…By changing the cooling rate and heat input, the martensitic structure can be decreased. Heat treatment before and after welding has been shown to reduce the rate of cooling in the welding process [4]. The geometry of the weld has little effect on the physical and mechanical qualities of cast iron welds, but the type of filler employed does.…”

Análisis mecánico y microestructural en soldadura de fundición dúctil, mediante procedimiento TIG, con diferentes materiales de aporte y enfriamiento al aire

“…This is due to the high fluidity conferred by the high carbon content and the low melting point (Abboud, 2012;De La Torre et al, 2014;Wube Dametew, 2015). As a result of these characteristics, nodular cast irons are currently the most widely produced cast alloys in the world (Kumar et al, 2017).…”

Improving the Mechanical Strength of Ductile Cast Iron Welded Joints Using Different Heat Treatments

“…This structure in the HAZ can be tempered to a structure with less hardness [14]. The PWHT is usually advisable for the following reasons [30,31]: It improves the ductility and the machinability of the HAZ and the joint, it decomposes the carbides formed during welding processes, it transforms martensite into a less brittle structure, and it relieves residual stresses formed during the welding cycles. It is also possible to produce a similar effect to the PWHT by performing further welding passes, relative to the former ones in the welded joint.…”