Cemal Meran

Welding problems with thin brass plates and tungsten inert gas pulse welding

Abstract Brass materials are widely used as engineering materials in industry because of their high strength, high corrosion resistance, and high electrical and thermal conductivity. They are easily shaped and they possess a pleasant appearance. However, it is difficult to weld brasses. The main problem with these alloys in fusion welding is the evaporation of zinc during the welding process. After welding, the weld metal becomes porous. Moreover, since the amount of zinc in the alloy is reduced due to evaporation, the brass material loses the physical and chemical properties which it normally possesses. Studies on weldability of brass materials are very few. There is very little information concerning the weldability of brass materials in the literature and general definitions are often seen. It is impossible to find studies on experimental investigations of the welding of brass materials apart for a few exceptions. There are virtually no studies to support experimental data about whether welding of brass materials is possible. The purpose of the present study is to determine suitable parameters by investigating the weldability of brass materials, and the difficulties involved. In order to enable low and controlled heat input into the welding bead, TIG pulse welding is used during experimental studies. The physical and chemical properties of welding beads (penetration, tensile strength, Erichsen deep drawing value, chemical composition of internal structure) have been determined and evaluations have been made.

Joint strength of friction stir welded AISI 304 austenitic stainless steels

Abstract In this study, AISI 304 (X5CrNi18-10) austenitic stainless steels were joined by means of friction stir welding. The welded joint strength of stainless steels was influenced by many factors, such as different tool rotational speeds, traverse speeds, compressive tool forces, and tool angles, etc. There is a strong interrelation among the friction stir welding design parameters. The effects of design parameters on the welded joint were analyzed using a genetic algorithm. Appropriate design parameter configurations led to fine-grained microstructures that resulted in higher tensile strength joints compared to the base material. The best design configuration that led to 1.16 times higher strength than the base material was achieved with 47.5 mm min−1 traverse speed, a rotational speed of 1 180 min−1, compressive tool force of 7 kN and tool tilt angle of 2.0°.

The effects of tool rotation speed and traverse speed on friction stir welding of AISI 304 austenitic stainless steel

Abstract In this study, AISI 304 (X5CrNi18-10, material identification number 1.4301) austenitic stainless steels, 3.0 mm thick, were joined by friction stir welding by applying different tool rotation speeds and traverse speeds, compressive forces and tool angles. The strength of the welded joints was improved by selecting suitable welding parameters. The maximum notch impact toughness was achieved on samples produced with 950 rpm rotation speed, 60 mm min−1 traverse speed, 9 kN compressive force, and 1.5° tool tilt angle. The maximum tensile strength of the weld zone was obtained on samples welded with 47.5 mm min−1 traverse speed, a rotational speed of 750 rpm, compressive force of 9 kN and tool tilt angle of 1.5°. The traverse speed of 47.5 mm min−1 was found to optimize the results of tensile strength and impact tests. Fine-grained microstructures occurred in the welded area. The weld joints obtained with friction stir welding have lower tensile strength compared to that of the base material. The experimental results indicate that AISI 304 austenitic stainless steels can be successfully joined considering both the strength of the welded joint and the appearance of the welding bead by selecting proper tool material and welding parameters using friction stir welding.

Usability of Boron as an Alloying Element in Gray Cast Iron Rollers and its Effect to Abrasive Wear Behaviour

In this study, usability of boron as an alloy element in gray cast iron and its effect to abrasive wear behaviour were investigated. Pin-on-drum wear tests at the room temperature carried out for seven low nickels alloyed gray cast irons with different boron addition. The mass losses, hardness values and microstructures for gray cast iron specimens with different boron alloyed were investigated for determining wear behaviour. The pin for the wear tests was manufactured from X210Cr12 cold work tool steel with material number of 1.2080. Abrasive pin-on-drum wear tests were carried out at a 165 N constant load and two different sliding speeds that are closely related to the appropriate operating conditions in rolling mills. The experimental studies have shown that wear rate decrease with increasing boron amount in chemical composition of the alloy and the wear rate at high sliding speed has decreased more rapidly than the rate at the low sliding speed with increasing boron amount.