Laser-Assisted Bending

2007 ◽  
Vol 344 ◽  
pp. 235-241 ◽  
Author(s):  
Kari Mäntyjärvi ◽  
Markku Keskitalo ◽  
Jussi A. Karjalainen ◽  
Anu Leiviskä ◽  
Jouko Heikkala ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Strain Hardening ◽  
Process Parameters ◽  
Laser Power ◽  
High Strength ◽  
Material Strength ◽  
Material Structure ◽  
Original Material ◽  
Heat Sources ◽  
Conventional Procedure

When sheets of high-strength (HS) and ultra-high-strength (UHS) steels are bent by a press brake the process suffers from large bending forces, considerable springback, and eventual cracks. Additionally, some unpredictable effects, such as lost contact to the punch, caused by strain hardening may occur producing a bend with erroneous radii. The strain hardening of the bending line may make further processes, such as forming or welding, more complex. One solution to these problems is to anneal the bending line with a laser in advance. Of course, it is also possible to utilise other types of heat sources, but the laser can offer the most precisely controlled heat treatment. The proper process parameters depend on the material, and it has been noticed that inadequate process parameters may harden the material instead of annealing. In this work some experiments on bending sheet metal samples of HS or UHS steel with previously laser-annealed bending lines have been carried out and the outcome analysed. The results show that the annealing produces better bending results compared to the conventional procedure. This includes lower springback, less hardening in the bending line and more precise geometry of the bend. It can be even suggested that proper annealing with strain hardening in bending will produce the original material structure. Obviously, more theoretical and experimental work is required to optimise the process parameters including the laser power and speed for each pair of material strength and thickness.

The Bauschinger Effect in a High-Strength Steel

1966 ◽  
Vol 88 (2) ◽  
pp. 480-488 ◽  
Author(s):  
R. V. Milligan ◽  
W. H. Koo ◽  
T. E. Davidson
Keyword(s):  
Heat Treatment ◽  
Yield Strength ◽  
Strain Hardening ◽  
Uniaxial Tension ◽  
High Strength Steel ◽  
Bauschinger Effect ◽  
High Strength ◽  
The Other ◽  
Material Structure ◽  
Permanent Strain

The object of this work was to evaluate quantitatively the Bauschinger effect in a 4330 modified steel as a function of strength level and structure as derived from variations in heat-treatment. Material having martensitic, pearlitic, and bainitic structures was studied utilizing a uniaxial tension-compression specimen. Various ways of defining the magnitude of the Bauschinger effect are explained. One is a conventional approach as suggested by Welter, the other a technique which takes strain-hardening into account. The results show the Bauschinger effect to be independent of yield strength for three different strength levels of the martensitic material. It is only mildly influenced by material structure and independent of the direction of overstrain. The Bauschinger effect increases with increasing permanent strain up to approximately 2 percent and thereafter remains essentially constant.

Fabrication Process for a High Strength 9Cr-2W Steel Sheet

2010 ◽  
Vol 638-642 ◽  
pp. 2263-2267
Author(s):  
Tae Kyu Kim ◽  
Chang Hee Han ◽  
Sung Ho Kim ◽  
Chan Bock Lee
Keyword(s):  
Heat Treatment ◽  
Cold Rolling ◽  
Process Parameters ◽  
Carbon Concentration ◽  
Room Temperature ◽  
Steel Sheet ◽  
High Strength ◽  
Tensile Tests ◽  
Fabrication Process ◽  
Martensitic Steels

This study deals with the fabrication of high strength ferritic/martensitic steels by a control of both the carbon concentration and the fabrication process parameters. The 9Cr-2W steels containing a carbon concentration of 0.05, 0.07 and 0.11 wt% were normalized at 1050oC for 1 h, followed by a tempering at 550 and 750oC for 2 h, respectively. The results of the tensile tests at room temperature indicated that the tensile strengths were increased with an increase of the carbon concentration from 0.05 wt% to 0.07 wt%, but no more increase was observed when the carbon concentration was increased further up to 0.11%. After a cold rolling from a 4 mm to a 1 mm thickness without/with an intermediate heat treatment and a final heat treatment, the results of the tensile tests exhibited that superior tensile properties were obtained when the fabrication processes were composed of a tempering at 550oC, and a cold rolling with several intermediate heat treatments. These results could be attributed to the finely distributed precipitates in the partially recrystallized matrix. The optimized carbon concentration and the controlled fabrication process parameters are thus suggested to fabricate a high strength 9Cr-2W steel sheet.

Microstructure and Mechanical Propertiesof Ti/Cu-Cr/S20C and Ti/Cu-Ag/S20C Clad Composites

2013 ◽  
Vol 376 ◽  
pp. 153-157 ◽  
Author(s):  
Jong Su Ha ◽  
Sun Ig Hong
Keyword(s):  
Heat Treatment ◽  
High Pressure ◽  
Strain Hardening ◽  
Intermetallic Compounds ◽  
Mechanical Performance ◽  
High Strength ◽  
Strengthening Mechanism ◽  
Reaction Products ◽  
Heat Treated ◽  
Strength And Ductility

In this study Cu-Ag or Cu-Cr layer was sandwiched by Ti and Fe plates and the three layers of Ti/Cu-8Ag/S20C were clad by High Pressure Torsioning(HPT). The effect of post-HPT heat treatment on the interfacial reaction products and the mechanical performance in Ti/Cu-Ag/S20C and Ti/Cu-Cr/S20C clad material were studied. Cu4Ti3 and Cu4Ti Intremetallic compound layers were observed at the Ti/Cu-Ag and Ti/Cu-Cr interfaces in the clad heat-treated at 500°C where as no intermetallic compounds were observed at the Cu-Ag/S20C and Cu-Cr/S20C interfaces. The strength of as-HPTed Ti/Cu-8Ag/S20C is much higher than that of Ti/Cu-1Cr/S20C. The strengthening mechanism of Cu-Ag deformed severely is the interface and strain hardening in which dislocations are deposited at the Cu/Ag interfaces and can contribute to the strengthening of the clad composite just after HPT processing, rendering the high strength just after processing. In both clad composites, the strength and ductility increased after heat treatment at 350°C, which are likely caused by the enhanced bonding at the interfaces.

scholarly journals Structural Aspects of Execution and Thermal Treatment of Welded Joints of Hardox Extreme Steel

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 915 ◽  
Author(s):  
Konat
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Welded Joints ◽  
Base Material ◽  
Steel Structures ◽  
High Strength ◽  
Carbon Equivalent ◽  
Material Structure ◽  
Welding Processes ◽  
Structural Aspects

The paper presents structure and mechanical properties of welded joints of the high-strength, abrasive-wear resistant steel Hardox Extreme. It was shown that, as a result of welding this steel, structures conducive to lowering its abrasion-wear resistance are created in the heat-affected zone. Width of the zone exceeds 60 mm, which results in accelerated wear in the planned applications. On the grounds of the carried-out examinations of structures and selected mechanical properties, a welding technology followed by heat treatment of heat-affected zones was suggested, leading to reconstruction of HAZ structures that is morphologically close to the base material structure. In spite of high carbon equivalent (CEV) of Hardox Extreme, the executed welding processes and heat treatment did not result in the appearance, in laboratory conditions, of welding imperfections in the welded joints.

Residual Stress Analysis and Weld Bead Shape Study in Laser Welding of High Strength Steel

2013 ◽  
Author(s):  
Wei Liu ◽  
Fanrong Kong ◽  
Radovan Kovacevic
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Laser Welding ◽  
Welding Speed ◽  
High Strength Steel ◽  
Laser Power ◽  
Measurement Data ◽  
Welding Process ◽  
High Strength ◽  
Weld Bead

The X-ray diffraction (XRD) technique is employed to measure residual stress induced by the laser welding of 6.7 mm thick ASTM A514 high strength steel plates. The distribution of residual stress in the weld bead is investigated. The results indicate that the fusion zone (FZ) has the maximum tensile stress, the transition from tensile to compressive stress tends to appear in the heat affected zone (HAZ), and the initial stress far from the weld center are not influenced by the welding process. Based on the measurement data, the influence of the laser power and the welding speed on residual stress is obtained. The magnitude of residual stress near the weld bead increases with an increase in laser power or a decrease in welding speed. The welds with incomplete penetration have a considerably lower magnitude of residual stress in FZ than ones with full penetration. Post-weld heat treatment is utilized to relieve residual stress in the weld bead. Although residual stress is not completely relieved after the heat treatment, a dramatically reduced magnitude and much more uniform distribution are achieved. In addition, the effects of the laser power, the welding speed, the laser spot diameter, and the gap between two plates on the weld shape are also studied.

Sheet Forming Processes for AW-7xxx Alloys: Relevant Process Parameters

2016 ◽  
Vol 879 ◽  
pp. 1036-1042 ◽  
Author(s):  
Manoj Kumar ◽  
Georg Kirov ◽  
Florian Grabner ◽  
Ermal Mukeli
Keyword(s):  
Heat Treatment ◽  
Process Parameters ◽  
Heat Treatment Temperature ◽  
Room Temperature ◽  
Hot Stamping ◽  
High Strength ◽  
Treatment Temperature ◽  
Quenching Rate ◽  
Forming Temperature ◽  
Cold Stamping

High strength AW-7xxx sheet alloys are promising candidates to manufacture crash relevant parts, but their limited formability at room temperature presents a major challenge. Formability is controlled through heating rate, heat treatment temperature and time, quenching rate, forming temperature and strain rate. In the literature retrogression forming, W-temper forming, warm forming and hot stamping processes have been proposed to improve the formability of AW-7xxx alloys. Of these the greatest improvement in formability comes from W-temper forming and hot stamping. Considering the similarity to the conventional forming processes of cold stamping for aluminium and hot stamping for steel, the W-temper forming and hot stamping of aluminium are promising for AW-7xxx alloys.

scholarly journals Mechanical Properties of High-Strength Cu–Cr–Zr Alloy Fabricated by Selective Laser Melting

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5028
Author(s):  
Fujia Sun ◽  
Ping Liu ◽  
Xiaohong Chen ◽  
Honglei Zhou ◽  
Pengfei Guan ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Laser Power ◽  
High Efficiency ◽  
High Strength ◽  
Scanning Speed ◽  
Laser Melting ◽  
Ansys Simulation ◽  
Zr Alloy

The approximate process range for preparing the Cu–Cr–Zr alloy by selective laser melting (SLM) was determined by ANSYS simulation, and the influence of the SLM process parameters on the comprehensive properties of the SLM-formed alloy was studied by the design of experiments. The Cu–Cr–Zr alloy with optimum strength and hardness was prepared with high efficiency by optimizing the process parameters for SLM (i.e., laser power, scanning speed, and hatching distance). It is experimentally shown that tensile strength and hardness of the SLM alloy are increased by increasing laser power and decreasing scanning speed, whereas they are initially increased and then decreased by increasing the hatching distance. Moreover, strength, roughness and hardness of the SLM alloy are optimized when laser power is 460 W, scanning speed is 700 mm/s and hatching distance is 0.06 mm. The optimized properties of the SLM alloy are a tensile strength of 153.5 MPa, hardness of 119 HV, roughness of 31.384 μm and relative density of 91.62%.

Study for Sheared Edge Quality of High Strength Steel Sheet

2014 ◽  
Vol 626 ◽  
pp. 252-257
Author(s):  
Soo Sik Han
Keyword(s):  
Process Parameters ◽  
High Strength Steel ◽  
Steel Sheet ◽  
High Strength ◽  
Material Strength ◽  
Burr Height ◽  
Sheared Edge ◽  
Edge Quality ◽  
Line Direction

The empirical approach was adopted to investigate the process parameters that effect on the quality of high strength steel sheet sheared edge. As a result of study, the quality of sheared edge that can be represented as the ratio of the shiny burnished surface to the sheared surface was not under influence of die clearance, lubrication and cutting line direction but under influence of the material strength and the usage of lower pad. The roll-over and burr height is highly affected by the die clearance and the usage of lower pad. The lower pad underneath of blank is of help to reduce the amount of roll-over and burr even at large die clearance.

CMW 100

Alloy Digest ◽  
2000 ◽  
Vol 49 (10) ◽  
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
Copper Alloy ◽  
High Strength ◽  
Heat Treating ◽  
Age Hardening ◽  
High Tensile Strength ◽  
Electrical Components ◽  
Flash Welding ◽  
Hardening Heat Treatment

Abstract CMW 100 is a copper alloy that combines high tensile strength with high electrical and thermal conductivity. It responds to age-hardening heat treatment. It is used for flash welding dies, springs, electrical components, high-strength backing material for brazed assemblies, and wire guides. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as fatigue. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: CU-29. Producer or source: CMW Inc. Originally published as Mallory 100, August 1955, revised October 2000.

CONFLEX 720

Alloy Digest ◽  
1964 ◽  
Vol 13 (7) ◽  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Physical Properties ◽  
Surface Treatment ◽  
Nickel Alloy ◽  
High Strength ◽  
Heat Treating ◽  
Age Hardening ◽  
Copper Manganese ◽  
Hardening Heat Treatment

Abstract CONFLEX 720 is a copper-manganese-nickel alloy that responds to an age-hardening heat treatment for high strength and corrosion resistance. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as heat treating, machining, joining, and surface treatment. Filing Code: Cu-143. Producer or source: Metals & Controls Inc..

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