ANALYSIS OF CHANGE IN MECHANICAL PROPERTIES OF LOW ALLOY STEEL (SIMILAR TO AISI 8740) FRICTION WELDED WITH INCONEL 718 (AUSTENITIC NICKEL- CHROMIUM BASED SUPERALLOY) AFTER HEAT TREATMENT (original) (raw)
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Advances in Mechanical Engineering, 2015
This work describes a post-weld heat treatment for a precipitation-hardened nickel alloy. Inconel X-750 is a nickel-based superalloy for gas tungsten arc welding processes. The materials were heat-treated in two steps: solution and aging. The post-weld heat treatment variables examined in this study included post-weld heat treatment temperatures of 705°C, 775°C, and 845°C and post-weld heat treatment time of 2-24 h in 2-h increments. The resulting materials were examined using the full factorial design of experiments to determine the resulting material hardness and observed with optical microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy in the fusion zone and heat-affected zone. The results show that a longer post-weld heat treatment time corresponds to larger g 0 precipitates and a smaller amount of Cr 23 C 6 at the grain boundaries, which can decrease the overall hardness. The post-weld heat treatment analysis indicates that an increase in the amount of g 0 results in better mechanical properties for particles with octagonal shapes and a small size. A factorial analysis, which was conducted on the relationship between the post-weld heat treatment temperature and time to the hardness of the fusion zone, had a 95% confidence level.
Materials Science and Engineering: A, 2014
Alloy 718 rods in two different heat treated conditions (solution treatment (ST) and ST followed by aging (STA)) were friction welded. The weld joints were subjected to two different post-weld heat treatments (direct aging (DA) and STA). Tensile tests were carried out at 650 1C with an initial strain rate of 10 À 4 s À 1. Stress rupture tests were performed at 650 1C at a constant load with an initial stress level of 690 MPa. The ultimate tensile strength values for all conditions, expect for base material in ST condition and weld joints with prior ST or STA in the as-welded condition, were higher than the minimum value of 1000 MPa specified by the Aerospace Material Specification for the base material in STA condition. The weld joint specimen in the as-welded state with prior STA condition failed in heat affected zone (HAZ). Though strengthening precipitates (γ 00) dissolved in weld metal and HAZ during welding, HAZ was weaker than weld metal due to coarser grains and so failure occurred in HAZ. In all other conditions, samples failed in base metal. The stress rupture properties such as minimum creep rate and time to rupture of the base material in ST condition and as-welded joints with prior ST or STA condition are almost same. The sample subjected to STA both before and after welding exhibits the best stress rupture properties. It may be attributed to homogenization as well as moderate coarsening of grain structure of weld zone and fine and uniform distribution of strengthening precipitates throughout the weldment. However, to obtain the best combination of tensile and stress rupture properties, the material should be welded in ST condition and it should be subjected to direct aging after welding.
Effect of Pre- and Post-weld Heat Treatments on Linear Friction Welded Ti-5553
Metallurgical and Materials Transactions A, 2014
The Al-Cu 206 cast alloys with varying alloy compositions (i.e., different levels of Fe, Mn, and Si) were investigated to evaluate the effect of the iron-rich intermetallics on the tensile properties. It is found that the tensile strength decreases with increasing iron content, but its overall loss is less than 10 pct over the range of 0.15 to 0.5 pct Fe at 0.3 pct Mn and 0.3 pct Si. At similar iron contents, the tensile properties of the alloys with dominant Chinese script iron-rich intermetallics are generally higher than those with the dominant platelet phase. In the solution and artificial overaging condition (T7), the tensile strength of the 206 cast alloys with more than 0.15 pct Fe is satisfactory, but the elongation does not sufficiently meet the minimum requirement of ductility (>7 pct) for critical automotive applications. However, it was found that both the required ductility and tensile strength can be reached at high Fe levels of 0.3 to 0.5 pct for the alloys with well-controlled alloy chemistry and microstructure in the solution and natural aging condition (T4), reinforcing the motivation for developing recyclable high-iron Al-Cu 206 cast alloys.
Metals
Heat-affected zones (HAZs) of Inconel 939 (IN-939) superalloy are susceptible to cracking during welding process. Preventing cracking during the repair welding of turbine components is important. In this study, the effects of heat input and pre-welding heat treatment on the microstructure, mechanical properties and crack formation in tungsten inert gas welding of IN-939 were investigated. The whole specimens were welded using Inconel 625 filler in an Ar atmosphere and characterised by metallographic examinations and hardness measurements. Results showed that the microstructures of IN-939 HAZs were highly susceptible to cracking during welding due to increasing of γ′ volume fraction. All of these cracks appeared in the HAZs and grew perpendicular to the melting zone along the grain boundaries. In this survey, the pre-welding heat treatment and heat input strongly affected the HAZ microstructure and hardness. However, the pre-welding heat treatment with 67% impact was more effective t...
Advances in Materials Science and Engineering, 2022
High-temperature dissimilar connections built of Inconel 718 and AISI 410 martensitic stainless steel (MSS) are widely used in a range of industries, including boiler construction, the chemical industry, aerospace, and nuclear. When compared to other materials, Inconel 718 and AISI 410 martensitic stainless steel ofer superior strength and corrosion resistance under a variety of environmental conditions. Te rotational speed was adjusted between 1100 and 1500 RPM, while the friction pressure, friction time, forging pressure, and forging duration were all kept constant during the testing. Five sets of testing were performed, with the resultant tensile strength (both room temperature and hot tensile) and Vickers Hardness being recorded for each set of trials. To assess the structural integrity of the joints, a detailed microstructural investigation, SEM-EDS, and XRD were performed at their interfaces. Mechanical properties were revealed to be high at 1300 RPM due to the small grain size at the interface region; ultimate tensile strength and hardness were determined to be 571 MPa and 423 HV, respectively, due to the small grain size at the interface region. Additionally, a pitting corrosion study has been conducted on dissimilar welded joints at optimum conditions, and their results were discussed and compared with base metals.
Metallurgical and Materials Transactions A, 2013
This work describes a post-weld heat treatment for a precipitation-hardened nickel alloy. Inconel X-750 is a nickel-based superalloy for gas tungsten arc welding processes. The materials were heat-treated in two steps: solution and aging. The post-weld heat treatment variables examined in this study included post-weld heat treatment temperatures of 705°C, 775°C, and 845°C and post-weld heat treatment time of 2-24 h in 2-h increments. The resulting materials were examined using the full factorial design of experiments to determine the resulting material hardness and observed with optical microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy in the fusion zone and heat-affected zone. The results show that a longer post-weld heat treatment time corresponds to larger g 0 precipitates and a smaller amount of Cr 23 C 6 at the grain boundaries, which can decrease the overall hardness. The post-weld heat treatment analysis indicates that an increase in the amount of g 0 results in better mechanical properties for particles with octagonal shapes and a small size. A factorial analysis, which was conducted on the relationship between the post-weld heat treatment temperature and time to the hardness of the fusion zone, had a 95% confidence level.
A comparison of inertia friction welds in three nickel base superalloys
Materials Science and Engineering: A, 2006
In this paper the microstructure, mechanical properties and residual stresses are compared for three inertia friction welded nickel-base superalloys. In contrast to alloy 720Li and RR1000, for Inconel 718 welding produces a precipitation free region leading to significantly reduced strength near the weld line. As a result, for alloy 720Li the hoop stresses are 1.5 times, and in RR1000 two times, higher than the tensile hoop stresses for Inconel 718. The maximum tensile weld stresses in Inconel 718 and RR1000 are yield stress limited in the weld region. That stresses significantly below the yield stress are found near the weld for alloy 720Li may be because the inferior creep properties of alloy 720Li compared to RR1000 result in stress relief during cooling after welding. Post weld heat treatment at the standard maximum aging temperature for Inconel 718 (732 • C), relieved residual hoop stresses to below 400 MPa. To achieve a similar level of residual hoop stress, Alloy 720Li must be stress relieved at least 30 • C and RR1000 about 80 • C hotter.
Experimental evaluation of mechanical properties of friction welded mild steel
Turbo : Jurnal Program Studi Teknik Mesin
Friction welding is a solid state joining process used to join similar and dissimilar metals, not possible with other available welding techniques. Now a day’s Friction welding is most commonly used in industry that is aeronautical engineering, automobile engineering, submarine industry and heavy industry. In this research, an experimental setup was designed and fabricated in order to accomplish friction welded joints mild steel. Thereafter, the effect of forging pressures and rotation speed on the mechanical properties of friction welded ST 42 steels, produced by mechanical joining, have been investigated. Samples were welded under friction pressure 10 MPa by different forging pressures 25 MPa and 35 MPa with different rotation speed 1095 rpm, 1200 rpm, and 1400 rpm. The tensile strength values of the weldments were determined and evaluated. The top result is produced from sample were welded under forging pressures 35 MPa at rotation speed 1400 rpm that is tensile strength 437,27 N...
Effect of Pre-Post TIG Welding Heat Treatment on Cast NI Superalloy
2020
The effect of a pre (before) and post (after) heating welding treatment on the microstructure and mechanical properties of the scrap blades made of cast INC738LC superalloy is the main goal of the present investigation. The filler used in TIG welding was a INC 625 solution hardened superalloy as the proposed solution for hot cracking of the INC738LC cast superalloy in literature. The TIG welding was processed with respect to the constantly optimized parameters (current, voltage, speed, gas flux rate and number of passes) to make a mechanical properties comparison between the as received superalloy and the welded superalloy with heat treated specimens. The characterization techniques employed in this study are hardness measurements, tensile tests, optical microscopy and scanning electron microscopy. We found that the proposed preheating improves the TIG welding of the INC 738 LC superalloy specimens and the post welding heat treatment enhances its mechanical properties.
Rotary Friction Welding of Inconel 718 to Inconel 600
Metals
Nickel-based superalloys exhibit excellent high temperature strength, high temperature corrosion and oxidation resistance and creep resistance. They are widely used in high temperature applications in aerospace, power and petrochemical industries. The need for economical and efficient usage of materials often necessitates the joining of dissimilar metals. In this study, dissimilar welding between two different nickel-based superalloys, Inconel 718 and Inconel 600, was attempted using rotary friction welding. Sound metallurgical joints were produced without any unwanted Laves or delta phases at the weld region, which invariably appear in fusion welds. The weld thermal cycle was found to result in significant grain coarsening in the heat effected zone (HAZ) on either side of the dissimilar weld interface due to the prevailing thermal cycles during the welding. However, fine equiaxed grains were observed at the weld interface due to dynamic recrystallization caused by severe plastic de...