Impact Toughness Of Welded Joints Research Articles

EFFECT OF VARIATION OF MAGNETIC INDUCTION SOLENOID VALUES ON TENSILE AND IMPACT STRENGTH FOR WELDING BETWEEN LOW CARBON STEEL AND MEDIUM CARBON STEEL

The use of solenoid magnets in welding processes has attracted attention due to their potential to influence the properties of welded joints. This research investigates the effect of the size of the magnetic induction solenoid on the tensile strength and impact toughness of welds between mild steel and medium carbon steel. Welding experiments were carried out using various sizes of solenoid magnets (0; 1.71mT; 2.11mT; 2.31mT; 2.60mT), and the welding results were tested for tensile strength and impact toughness. The findings show that the size of the magnetic induction solenoid has a significant effect on the mechanical properties of the weld. The larger induction size in this study increased the tensile strength of the welded joint, namely 431.576 N/mm2 without induction and 533.33 N/mm2 with induction. Meanwhile, the impact toughness of welded joints also increases, namely 95.92N.m without treatment and 217.35N.m with induction.

Study on the Microstructure and Properties of Welded Joints of Laser Shock Peening on HC420LA Low-Alloy High-Tensile Steel.

Laser shock peening is a promising surface strengthening technology that can effectively improve the mechanical properties of materials. This paper is based on the laser shock peening process for HC420LA low-alloy high-strength steel weldments. Contrast analysis of the evolution of the microstructure, residual stress distribution and mechanical properties of the welded joints before and after the laser shock peening on each region is carried out; a combination of tensile fracture and impact toughness fracture morphology analyses of laser shock peening on the welded joint strength and toughness regulation mechanism are also completed. The results show that the laser shock peening can refine the microstructure of the welded joint effectively, the microhardness of all areas of the joint increases and the weld residual tensile stresses are transformed into beneficial residual compressive stresses, affecting a layer depth of 600 μm. In addition, the strength and impact toughness of welded joints of HC420LA low-alloy high-strength steel are improved.

Effect of adding TiO2 nanoparticles on the impact toughness for welding joints of mild steel

ABSTRACT The application of nanotechnology in the welding process has great importance in developing the mechanical properties of welding joints. The aim of this paper was to investigated the effect of addition titanium dioxide nanoparticles(TiO2) to welding joints by using cold spary technique and study the possibility of improving the impact toughness of the welding joint and increase its operation life. Three weight fraction are used of TiO2 (0.75%, 1.5%, and 2%).The results showed there are improvements in the Impact toughness of welded joints with an increase of TiO2 concentrations. The average Impact toughness for the welded sample without TiO2 was (162.4 J), while the average Impact toughness for the welded sample with (1.5) % TiO2 NPs. was (231.2 J) at increasing ratio of (42.36 %) due to the good toughness properties of TiO2 that increase the toughness of welding zone. The Microstructure image by SEM showed that the addition of TiO2 decreases the grain size in the welding zone and makes it more homogeneous, which gives it more toughness. The EDS analysis shows that increase TiO2 NPs leads to increase the amount of Ti and decrease the amount of Mn, and Si.

Analysis of Influence of the Welding Procedure on Impact Toughness of Welded Joints of the High-Strength Low-Alloyed Steels

This paper presents results of comparison of two welding procedures’ influence on selected properties of the welded joints of high-strength low-alloyed steel (HSLA), specifically the impact toughness and the hardness distribution in the specific zones of “single V” butt multiple-pass welded joints. Based on results obtained from experiments, the two applied welding technologies were evaluated. They differ by the welding grove geometry and by the applied root pass welding procedure. Both procedures use MAG (Metal Active Gas) welding for execution of the filling and covering passes, while the root passes are executed by the MMA (Manual Metal Arc) procedure in the first case and by the MIG (Metal Inert Gas) procedure in the second. Experimentally obtained values of the fracture energy of the welded samples for both procedures were smaller than the values for the parent metal, which confirms the fact that welding causes degradation of the mechanical properties of HSLA steel; thus, any welding technology parameters must be so selected to mitigate this deficiency.

Improving Impact Toughness for Welding Joints of Steel by Adding TiO2 Nanoparticales

The using of nanotechnology in the welding process has great importance in developing the mechanical properties of welding joints for metals. This paper investigated the effect of addition TiO2 NPs to welding joints to improving the Impact toughness property of the welding joints. The cold spray coating method of the nanoparticles are used to adding the TiO2 NPs to the welding joints during the welding process. Three weight fraction are used for TiO2 NPs (0.75%, 1.5%, and 2%). The testing samples were prepared for Impact test, and microstructure by SEM. The results show the increasing in Impact toughness of welded joints with an increase of TiO2 NPs concentrations. The average Impact toughness for the welded sample without TiO2 NPs. was (162.4 J), while the average Impact toughness for the welded sample with (1.5)% TiO2 NPs. was (231.2 J) with improving rate of (42.36%). The Microstructure images by SEM show the adding of TiO2 NPs decreases the grain size and homogenous region in welded joints cross-section compared with a sample without adding TiO2 NPs. The EDS analysis show that increase Ti contain and decrease (Mn and Si) contain with increase TiO2 NPs.

Effect of Tool Offset and Rotational Speed in Dissimilar Friction Stir Welding of AISI 304 Stainless Steel and Mild Steel

In the present study, dissimilar friction stir welding was carried out between stainless steel (UNS S30400) and mild steel (UNS G10080) plates of 4 mm thickness using a tungsten carbide tool. The influence of tool rotational speeds (600, 875 rpm) and tool offsets (0.6, 1.2 mm) on mechanical properties, i.e., hardness, tensile strength, and impact toughness of welded joints was investigated. Maximum tensile strength of the joint was about 107.6% of the mild steel under rotational speed of 875 rpm and tool offset of 1.2 mm. The maximum hardness reached in the stir zone was about 281 HV0.5 due to the phase transformations and grain refinement. Charpy’s notch toughness of the welded joints was observed lower than the base materials. The microstructural characterizations were carried by using an optical microscope, and FESEM–EDS analysis which revealed the complex material mixing and material movement during the welding. Tungsten-rich bands were observed in the weld micrograph especially toward the advancing side. During this study, various wear mechanisms like oxidation wear, abrasive wear, and adhesion wear were responsible for the degradation of tungsten carbide tool.

Effect of Welding Process on Microstructure and Properties of High Strength Steel Joints

S900MC high strength steel was selected as the research object, and different MAG welding processes were designed according to the practical application of construction machinery. The microstructure, tensile test and impact test of the welded joints were carried out under different conditions. The effects of welding heat input, preheating temperature and cooling time t8/5 on the tensile strength and impact toughness of welded joints were studied. The results show that the microstructure of the welded joint is composed of weld, fusion zone, superheated zone, fine grain zone and incomplete recrystallization zone. When the welding line energy or preheating temperature is increased, the cooling rate decreases, the strength of the welded joint decreases. The impact absorption energy of the weld is about 50% higher than that of HAZ. With the increase of t8/5, the impact absorption energy of the weld and HAZ increases first and then decreases. When t8/5 is 15-20s, the impact absorption energy is the largest.

Microstructural Evolution and the Effect on Hardness and Impact Toughness of Sanicro 25 Welded Joints After Aging at 973 K

Sanicro 25 tubes were welded using Alloy 617 mod. as the filler material, and the welded joints were aged at 973 K up to 10,000 hours. The hardness and impact toughness of welded joints were measured, and the microstructural evolution after aging was systematically investigated by means of OM, SEM, and TEM. After aging, the predominant precipitates in the base metal are secondary NbCrN, Cu-rich particles, and M23C6. The great increase in the hardness of base metal at the early stage of aging is attributed to the precipitation of secondary NbCrN, Cu-rich particles, and M23C6. The calculation of pinning force implies that secondary NbCrN possesses the strongest precipitation strengthening because it is extremely fine and stable. Also, Cu-rich particles are the key precipitates owing to the significant effect on the hardness change of base metal during aging. Aging results in the precipitation of needle-like M23C6 and spherical γ′ phase as well as large M23C6 particles at the grain boundaries in the weld metal. Hence, the hardness of weld metal increases. With the increasing aging time, the growths of M23C6 and γ′ phase decrease the hardness. Some cuboids of M23C6 are observed after long-term aging. The significant decrease in the impact toughness of the aged welded joints mainly results from the growth of M23C6 at the grain boundaries and the interdendritic regions. Needle-like and cuboids of M23C6 further decrease the impact toughness.

Electromagnetic nature of the movement of liquid metal in the weld pool

The electromagnetic nature of movement of liquid metal in a weld pool is discussed. When increasing the welding speed as a result of decreasing the induction of the magnetic field at the back of the arc and increasing the electromagnetic force directed forward and reducing the size of the active arc spot, the speed of movement of the liquid metal increases in welding in the direction from the current supply and rapidly in welding towards the current supply. This confirms the electromagnetic nature of formation of undercutting. A method is described for high-speed one-sided welding with a compound electrode in which the active spot of the arc becomes larger, the arc and liquid metal of the pool move forward, the electromagnetic forces directed downwards in the area of the side edges of the pool decrease, and the resultant welded joint is of high quality without undercutting, the reverse bead forms on a flux cushion and the impact toughness of welded joints increases.

Magnetic field in electric arc welding

It is shown that the longitudinal magnetic field of welding current in welding of two sheets transforms to the field of a single sheet and this confirms the electromagnetic nature of the interatomic binding forces. At a gap of 0.002 m and as a result of the separation of the lines of force, the induction of the longitudinal magnetic field of welding current rapidly increases and the arc starts to rotate. The electromagnetic force and magnetic pressure directed forward and to the side edges of the weld pool then appear. This results in the movement of liquid metal to the front part of the crater and to the side edges, formation of welded joints without undercutting, and confirms the electromagnetic nature of the formation of undercutting in one-sided high-speed welding. A method of one-sided high-speed welding with a compound electrode on a flux cushion with a gap of 0.002 m has been developed. The method improves the stability of the process and impact toughness of welded joints.

Microstructural characterization and wide temperature range mechanical properties of NiCrMoV steel welded joint with heavy section

Abstract

Development of additions to welding fluxes in welding of low-alloy steels

It is shown that the oxygen content of metal of welded joints in automatic submerged arc welding can be reduced by adding additions to the flux. The content of the non-metallic inclusions is reduced, and the mechanical properties and impact toughness of welded joints at sub-zero temperatures increase. The results also show that when adding up to 6% of a carbon-containing addition to the AN-60 flux, the carbon content of the weld metal in welding a low-alloy steel does not exceed the permissible value.

Effect of welding conditions on the impact toughness of welded joints in titanium alloys

Effect of the welding conditions and annealing on the impact strength of different heat-affected areas of the titanium welded joints is studied. Maximum impact strength is established in the range of 350–550°C, in practice this coincides with the temperature peaks for short-time strength and fatigue life.

Effect of modifying additions on the impact toughness of welded joints in low‐carbon steels produced with electrodes with a basic coating

(2001). Effect of modifying additions on the impact toughness of welded joints in low‐carbon steels produced with electrodes with a basic coating. Welding International: Vol. 15, No. 12, pp. 983-985.

Effect of preliminary heat treatment on the impact toughness of welded joints in a high-strength steel

Investigations were carried out into structural changes in preliminary heat treatment which affect the increase of impact toughness of welded joints in the conditions after strengthening by heat treatment. These investigations were made on electron beam welded joints produced in 35KhS2N3M1F steel 15 mm thick

Structural and mechanical heterogeneity of heat affected zone and impact toughness of welded joints in structural steels

Structural and mechanical heterogeneity of heat affected zone and impact toughness of welded joints in structural steels

Impact toughness of welded joints of niobium alloys

1. It was found that the impact toughness of welded joints of niobium alloys varies with the welding speed. 2. The impact toughness reaches the highest values at welding speeds of 40–60 m/h and then remains constant. The impact toughness changes least for niobium alloys with solid solution hardening. 3. Separation of the impact toughness into its component parts showed that higher welding speeds are preferable. 4. The optimum conditions for heat treating weld seams in alloys 2 and 4 are 1200 and 1200–1300°C respectively with holding for 1h.