Welded joints with new properties and provision of such properties by ultrasonic impact treatment

Abstract

Non-detachable welded joints with certain new or improved properties and the provision of such non-detachable welded joints by ultrasonic impact treatment, is described involving conforming to select treatment parameters to control the formation of predetermined properties and thus provide improved qualities and reliability to a joint based on the task to be served by the welded joint. The treatment parameters include repetition rate and length of the ultrasonic impact, pressing force exerted on the ultrasonic impact tool against the surface being treated, and impact amplitude.

1 . An ultrasonic impact treated non-detachable welded joint comprising at least one predetermined structural property resulting from ultrasonic impact treatment of said welded joint, said at least one predetermined structural property including at least one of: 
 surface roughness and relief of at least about 0.1 μm;    a radius between surfaces of at least about 0.5 mm;    a depth of a groove along a weld toe line or line between any surfaces in a stress concentration area of up to about 2 mm with a width of said groove being up to about 10 mm;    increase of material mechanical properties in a stress concentration area, as to strength by at least about 1.5 times and impact strength by at least about 1.2 times;    plastic deformation, favorable compressive stresses and a favorable relative change in microhardness to a depth of up to about 7 mm;    distribution of elastic compressive stresses due to plastic deformation of material in section normal to a surface to a depth of up to 10 mm;    relaxation of process induced residual stresses due to ultrasonic fluctuating stress wave with an amplitude of at least about 0.05 of a material yield strength, to a depth of up to about 12 mm;    favorable residual stresses of a first and a second kind on and under a surface to a predetermined depth of at least material yield strength and ultimate strength based on task application;    compensation for residual process induced deformations by at least about 40% of those occurring without ultrasonic impact treatment application with increased stress corrosion resistance by up to about 10 times;    increase in corrosion-fatigue strength by up to about 2.5 times and a life span in a corrosion environment of up to about 20 times under variable loading;    increase in fatigue limit in air under repeated or fluctuating stress by at least about 1.5 times and a life span by at least about 10 times to increase joint strength by at least 1 category; or formation of a white layer and an amorphous structure to a depth of at least about 50 μm.    
     
     
         2 . The ultrasonic impact treated non-detachable welded joint according to  claim 1 , wherein said welded joint is made of a high strength steel or alloy having a yield strength of σ>500 MPa following ultrasonic impact treatment and has a fatigue limit which is a minimum of about 30% greater than that of a steel or alloy with σ<500 MPa.  
     
     
         3 . The ultrasonic impact treated non-detachable welded joint according to  claim 1 , wherein said favorable compressive stresses have a depth of about 2 mm, with a magnitude at a surface greater than a yield strength and a fatigue limit of an untreated base material of the welded joint by a factor of up to about 1.5.  
     
     
         4 . The ultrasonic impact treated non-detachable welded joint according to  claim 1 , wherein said welded joint has a level of residual stresses of about 0.5 less of a yield strength of said welded joint; residual welding deformations of about 100% or less of a dimensional tolerance predetermined for said welded joint; and/or fatigue resistance equal to or greater than that of an untreated base material of said welded joint.  
     
     
         5 . The ultrasonic impact treated non-detachable welded joint according to  claim 1 , wherein said fatigue limit of a spot weld is increased by at least about 1.3 times that of an untreated base material and has increased fatigue resistance, yield point, ultimate strength and impact strength to a level equal to or greater than that of an untreated base metal material of the welded joint.  
     
     
         6 . The ultrasonic impact treated non-detachable welded joint according to  claim 1 , wherein said fatigue limit of a tack weld is at least about 1.3 times greater than that of an untreated base material of the welded joint and fatigue resistance, ultimate strength and impact strength are equal to or greater than that of the untreated base material.  
     
     
         7 . An ultrasonic impact treated non-detachable welded joint comprising structural properties resulting from ultrasonic impact treatment of said welded joint wherein parameters of said treatment include 
 oscillating system frequency of greater than zero to about 800 kHz,    pressure on an ultrasonic impact tool of greater than zero to about 50 kg,    ultrasonic transducer vibrational amplitude during impact of greater than 0 to about 120 μm,    ultrasonic frequency in a range of greater than zero to about 2500 Hz,    self-oscillation amplitude of the impact tool of greater than zero to about 5 mm, and    an average duration of impact of said ultrasonic impact tool being at least about  1  ms.    
     
     
         8 . An ultrasonic impact treated non-detachable welded joint comprising steel or steel alloy having a yield strength of σ>500 MPa, and structural properties resulting from ultrasonic impact treatment of said welded joint wherein parameters of said treatment include 
 an oscillating system frequency of about 27 kHz,    pressure on an ultrasonic impact tool of greater than zero to about 10 kg,    ultrasonic transducer vibrational amplitude during impact of at least about 30 μm,    ultrasonic frequency in a range of about 80-250 Hz,    self-oscillation amplitude of the impact tool of greater than zero to about 2 mm,    indenter diameter of about 3-6.35 mm, and    length of indenter being in a range of about 10-35 mm, wherein said welded joint has favorable compressive stresses to a depth of at least 2 mm.    
     
     
         9 . An ultrasonic impact treated non-detachable welded joint with improved stress concentration comprising a groove in a transition area between a weld material and a base material, said groove having radiuses at a boundary of the groove of at least about 0.5 mm, widths greater than zero to about 10 mm and depth of greater than zero to about 2 mm, and properties resulting from ultrasonic impact treatment of the welded joint wherein parameters of said treatment include 
 ultrasonic vibration amplitude during impact of greater than zero to about 50 μm at a frequency of greater than zero to about 80 kHz,    ultrasonic frequency of greater than zero to about 500 Hz,    self-oscillation amplitude of an ultrasonic impact tool of at least about 0.2 mm,    an off-duty factor of impact impulses of greater than zero to about 0.5, and    pressure on the ultrasonic impact tool of at least about 3 kg.    
     
     
         10 . An ultrasonic impact treated non-detachable welded joint with improved external loading properties comprising a joint metal of carbon structural steel, stainless steel, or aluminum and titanium alloys, and properties resulting from ultrasonic impact treatment of the welded joint wherein parameters of said treatment include 
 ultrasonic vibration amplitude during impact of greater than zero to about 50 μm at a frequency of greater than zero to about 80 kHz,    ultrasonic frequency of greater than zero to about 500 Hz with average duration being at least about 1 ms,    self-oscillation amplitude of an ultrasonic impact tool of at least about 0.2 mm, and    pressure on the ultrasonic impact tool of at least about 3 kg,    whereby compressive stresses and strength in a stress concentration area of the joint is greater than that present in the joint in the absence of ultrasonic impact treatment to compensate for external operational forces which cause in-service cracking.    
     
     
         11 . The welded joint of  claim 10  wherein said ultrasonic impact treatment includes ultrasonic impact of a weld toe of said welded joint and a load-carrying component on a loading side providing during treatment plastic deformation to create and distribute said compressive stresses.  
     
     
         12 . An ultrasonic impact treated non-detachable welded joint comprising a welded joint with compressive stresses in a plastic deformation area to a depth of at least about 2 mm and corresponding compressive stresses in an elastic deformation area sufficient to compensate for residual effect of the tensile stresses, and properties resulting from ultrasonic impact treatment of the welded joint wherein parameters of the treatment include pressure force of an ultrasonic impact tool of greater than zero to about 10 kg, 
 ultrasonic impact frequency of greater than zero to about 500 Hz,    average duration of ultrasonic impact of at least about 1 ms,    ultrasonic carrier frequency of greater than zero to about 100 kHz,    ultrasonic oscillation amplitude of an indenter during impact of at least about 30 μm, and    impact amplitude of at least about 0.2 mm.    
     
     
         13 . An ultrasonic impact treated non-detachable welded joint comprising deformation compensation within said joint to a value of 1>K o >−1 wherein K o  is a toolmarks overlap coefficient, and properties resulting from ultrasonic impact treatment of the welded joint wherein parameters of the treatment include 
 pressure force of an ultrasonic impact tool of at least about 4 kg,    ultrasonic impact frequency of at least about 100 Hz,    impact amplitude of at least about 0.2 mm,    average impact duration of at least about 1 ms,    carrier ultrasonic frequency of at least about 15 kHz,    ultrasonic vibration amplitude during impact of at least about 30 μm when said welded joint is made of steel or steel alloy and about 30 μm or less when said welded joint is made of an aluminum alloy or metal with a yield strength of up to about 235 MPa.    
     
     
         14 . The welded joint according to  claim 13  wherein said properties include modification of residual welding deformations to create rigid attachment with subsequent ultrasonic relaxation of residual welding stresses, or ultrasonic plastic deformation and redistribution of the weld metal.  
     
     
         15 . An ultrasonic impact treated non-detachable welded joint including 
 residual stresses of not greater than 0.5 of the yield strength of the welded joint,    residual welding deformations of not greater than 100% of dimensional tolerance specific to said welded joint, and    fatigue resistance of the welded joint is not less than the fatigue resistance of a base metal in said welded joint,    wherein parameters of ultrasonic impact treatment of said welded joint include    pressure upon an ultrasonic impact tool with a steel indenter is at least about 3 kg during manual treatment and greater than zero to about 20 kg during mechanized treatment,    ultrasonic impact frequency of at least about 0.2 mm,    carrier frequency of indenter ultrasonic vibrations of at least about 15 kHz, and    ultrasonic vibration amplitude during impact of at least about 20 μm when metal is above ambient temperature during treatment and at least about 30 μm when metal is at or about ambient temperature during treatment.    
     
     
         16 . An ultrasonic impact treated non-detachable welded joint comprising a steel joint structured as a corner joint with obtuse flank angles for a weld metal of the joint, said corner joint being resistant to root cracking based on ultrasonic impact treatment of said welded joint within parameters including 
 pressure force of an ultrasonic impact tool of at least about 3 kg during manual treatment or at least about 25 kg during mechanized treatment,    ultrasonic frequency of greater than zero to about 800 Hz,    ultrasonic impact amplitude of at least about 0.2 mm,    ultrasonic vibration carrier frequency of at least about 18 kHz,    ultrasonic vibration amplitude during impact of greater than zero to about 20 μm at a temperature above about 400° C., and    average ultrasonic impact duration of at least about 1 ms,    whereby weld metal is redistributed between a flange and a web in the corner joint.    
     
     
         17 . The welded joint of  claim 16  wherein said ultrasonic treatment provides a meniscus and fuses sharp edges of said welded joint such that upon solidification following said treatment smooth transitions are provided between a weld and a base metal of said welded joint increasing, to a level greater than said joint prior to treatment, joint properties of resistance to stress concentration and fatigue crack formation in a root of the weld.  
     
     
         18 . An ultrasonic impact treated non-detachable welded joint comprising a carbon steel or aluminum alloy spot welded joint with displaced tensile stress based on ultrasonic impact treatment of said spot welded joint within parameters including 
 ultrasonic impact frequency of at least about 80 Hz,    average impact duration of least about 1 ms at an amplitude of at least about 0.2 mm,    indenter ultrasonic vibration carrier frequency during impact of greater than zero to about 100 kHz,    ultrasonic vibration amplitude during impact in a range of from about 5-40 μm, and    pressure force on an impact tool of from about 3-30 kg.    
     
     
         19 . An ultrasonic impact treated non-detachable welded joint comprising a joint of carbon steel or aluminum alloy with a tack weld or a lap weld resistant to cracking at weld ends based on ultrasonic impact treatment of said welded joint within parameters including 
 ultrasonic impact frequency of greater than zero to about 2000 Hz,    average duration of ultrasonic impact of at least about 1 ms,    impact amplitude of at least about 0.2 mm,    indenter ultrasonic vibration carrier frequency of at least about 18 kHz,    indenter ultrasonic vibration amplitude during impact of at least about 25 μm for carbon steel and greater than zero to about 30 μm for aluminum alloy, and    pressure force of an ultrasonic impact tool against a treated surface of at least about 3 kg.    
     
     
         20 . An ultrasonic impact treated non-detachable welded joint comprising a corner welded joint of carbon steel or aluminum alloy having increased fatigue limit by at least a factor of at least 1.3 based on ultrasonic impact treatment of said corner welded joint within parameters including ultrasonic impact frequency of greater than zero to about 1200 Hz, 
 average duration of ultrasonic impact of at least about 1 ms,    ultrasonic impact amplitude of at least about 0.2 mm,    indenter ultrasonic vibration amplitude during impact of at least about 25 μm for carbon steel and not greater than about 30 μm for aluminum alloy,    pressure of an ultrasonic impact tool against a treated surface of said welded joint of at least about 3 kg.    
     
     
         21 . An ultrasonic impact treated non-detachable welded joint comprising a welded joint having weld metal structure phase homogeneity in all directions in the weld based on crystallization and recrystallization of the weld metal based on ultrasonic impact treatment of the welded joint within parameters including 
 pressure of an ultrasonic impact tool of from about 0.1-50 kg,    ultrasonic vibration carrier frequency at a transducer of from about 10-800 kHz,    ultrasonic vibration amplitude under no-load conditions and during impact of an ultrasonic tool at a carrier frequency of from about 0.5-120 μm,    self-oscillation amplitude of ultrasonic impact tool of from about 0.05-5 mm, and    average duration of ultrasonic impact of at least about 1 ms.    
     
     
         22 . An ultrasonic impact treated non-detachable welded joint comprising a joint of ferritic steel with a weld having activated crystallization and resistance to brittle fracture based on ultrasonic impact treatment of the welded joint within parameters including 
 ultrasonic impact frequency of greater than zero to about 2500 Hz,    ultrasonic impact amplitude of at least about 0.2 mm,    average duration of ultrasonic impacts of at least about 1 ms,    ultrasonic vibration carrier frequency of at least about 15 kHz,    ultrasonic vibration amplitude during impact of at least about 15 μm for metal not at ambient temperature and less than about 30 μm for treatment of metal at or about ambient temperature, and    pressure force of an ultrasonic impact tool against a treated surface of at least about 5 kg for manual treatment or at least about 10 kg for mechanized treatment.    
     
     
         23 . An ultrasonic impact treated non-detachable welded joint comprising a joint modified by ultrasonic impact to increase resistance to stress corrosion to a level greater than said joint untreated by ultrasonic impact, based on ultrasonic impact treatment of the welded joint within parameters including 
 ultrasonic impact frequency of greater than zero to about 500 Hz,    ultrasonic impact amplitude of at least about 0.5 mm,    average duration of ultrasonic impacts of at least about 1 ms,    ultrasonic vibration carrier frequency of at least about 15 kHz,    ultrasonic vibration amplitude during impact of at least about 20 μm, and    pressure force on an ultrasonic impact tool against a treated surface of at least about 5 kg.    
     
     
         24 . The welded joint according to  claim 23  wherein said joint has a surface roughness of not less than about 5 μm in a sampling length of 0.8 mm, a waviness of not less than about 15 μm at a sampling length of 2.5 mm, compressive stresses not less than yield strength of the joint, depth of plastic deformation and induced residual stresses of not less than about 1.5 mm, corrosion resistance of at least 2 times greater than in absence of the treatment, and corrosion-fatigue strength of not less than about 1.3 times that of the joint in absence of the treatment of the joint.  
     
     
         25 . An ultrasonic impact treated non-detachable welded joint comprising a welded joint structure containing at least one crack arrest hole in said structure, said at least one crack arrest hole having compressive stresses in the structure surrounding the at least one hole, wherein parameters of ultrasonic impact treatment of said welded joint structure containing said at least one crack arrest hole include 
 ultrasonic impact frequency of greater than zero to about 500 Hz,    ultrasonic impact amplitude of at least about 0.5 mm,    average duration of ultrasonic impacts of at least about 1 ms,    ultrasonic vibration carrier frequency of at least about 15 kHz,    ultrasonic vibration amplitude during impact of at least about 30 μm, and    pressure force on an ultrasonic impact tool against a treated surface of at least about 5 kg.    
     
     
         26 . An ultrasonic impact treated non-detachable welded joint comprising a structural combination including a welded joint with a bracket and a panel, wherein a radius cutout is present between the bracket and the panel, said structural combination has fatigue resistance of at least 1.3 times that of the structural combination when untreated by ultrasonic impact treatment, wherein said ultrasonic impact treatment of said structural combination is within parameters including ultrasonic impact frequency of greater than zero to about 300 Hz, 
 ultrasonic impact amplitude of at least about 0.5 mm,    average duration of ultrasonic impacts of at least about 1 ms,    ultrasonic vibration carrier frequency of at least about 15 kHz, ultrasonic vibration amplitude during impact of at least about 30 μm, and    pressure force on an ultrasonic impact tool against a treated surface of at least about 3 kg.    
     
     
         27 . An ultrasonic impact treated non-detachable welded joint comprising a welded joint with reduced martensite decomposition based on ultrasonic impact treatment of the welded joint within parameters including 
 ultrasonic impact frequency of greater than zero to about 800 Hz,    ultrasonic impact amplitude of at least about 0.5 mm,    average duration of ultrasonic impacts of at least about 1 ms,    ultrasonic vibration carrier frequency of at least about 15 kHz,    ultrasonic impact of at least about 30 μm, and    pressure force on an ultrasonic impact tool against a treated surface of at least about 10 kg.    
     
     
         28 . An ultrasonic impact treated non-detachable welded joint comprising a welded joint having a coating thereon, said coating being resistant to breakage upon ultrasonic impact treatment wherein said treatment has parameters which include ultrasonic impact frequency of greater than zero to about 1500 Hz, 
 ultrasonic impact amplitude of at least about 1 mm,    average duration of ultrasonic impacts of at least about 1 ms,    ultrasonic vibration carrier frequency of at least about 20 kHz,    ultrasonic vibration amplitude during impact of greater than zero to about 30 μm,    contact pressure and stress gradient at a boundary between individual ultrasonic impact tool marks of not greater than coating breaking strength, and    pressure force on an ultrasonic impact tool against a surface of at least about 3 kg.    
     
     
         29 . Process of analyzing and selecting an ultrasonic impact treatment for treating a welded joint to have one or more predetermined properties, comprising 
 (1) defining pre-treatment properties of material forming a weld of the joint and the welded joint itself;    (2) defining conformity of the properties of (1) to post-treatment properties to be provided in the joint;    (3) defining physical factors having an effect on the joint in context of the post-treatment properties to be provided in the joint;    (4) defining positive result criteria and effect of ultrasonic impact treatment on providing the post-treatment properties in the joint;    (5) defining a manner of ultrasonic impact treatment for the joint in context of providing the post-treatment properties in the joint, including defining ultrasonic impact treatment conditions in combination with parameters of a transducer, ultrasonic impact, indenter, pressure, mechanical properties and acoustic characteristics of the material to be treated; and    (6) conducting ultrasonic impact treatment on the joint in accordance with the definitions established in (1) to (5).    
     
     
         30 . Process according to  claim 29 , wherein said physical factors of (3) comprise one or more of plastic deformation caused by low frequency impact, ultrasonic plastic deformation during said impact treatment, amplitude and attenuation of ultrasonic stress wave in the material of the joint, and temperature and heat rejection rate at a contact point during ultrasonic impact.  
     
     
         31 . Process according to  claim 29 , wherein said post-treatment properties of (2) comprise one or more of geometric accuracy, residual deformations and nominal dimension tolerance thereof, residual stresses equilibrated within volume of the joint and structural segments of the material of the joint, acceptable stress concentration level and configuration of stress raisers responsible for load-carrying capacity of the joint, fatigue limit and fatigue resistance under low-cycle and high-cycle reversal and fluctuating loading, fatigue limit and resistance to corrosion and corrosion fatigue failures in aggressive environment under the low-cycle and high-cycle reversed and fluctuating loading and properties of the welded joint.  
     
     
         32 . Process according to  claim 29 , wherein the criteria of (4) comprise one or more of induced residual stress and deformation levels; relief, roughness and geometric modification of surface and transitional areas of the joint and modification of properties of the material in an area of treatment; relaxation and redistribution of residual stresses produced during manufacture of the joint prior to impact treatment; and modification of the joint as to type and conditions of resistance to a service load.  
     
     
         33 . Process according to  claim 29 , wherein the parameters of (5) comprise one or more of pressure on an ultrasonic impact tool being in a range of from about 0.1-50 kg; carrier ultrasonic frequency of the transducer being between about 10-800 kHz; amplitude of ultrasonic vibrations at said carrier frequency of between about 0.5-120 μm; ultrasonic impact frequency and self-oscillation frequency of the tool being between about 5-2500 Hz with duration of random ultrasonic impact in a range of from about 2-50 vibration periods at carrier ultrasonic frequency; self-oscillation amplitude of the tool being between about 0.5-5 mm; level of connection between a freely axially moving indenter and a transducer of the tool being within the claimed parameters; free ultrasonic impacts within said parameters selected in view of task, property and size requirements of the material and the joint.  
     
     
         34 . Process of treating a non-detachable welded structure comprising: 
 (a) subjecting at least a portion of a weld in a non-detachable welded structure to repeated ultrasonic impact by an ultrasonic impact tool to cause controlled plastic deformation in said weld and modify surface and transitional areas of the weld of said welded structure and thus modify one or more material properties in the welded structure;    (b) obtaining the material properties of (a) by controlling one or more select parameters of said repeated ultrasonic impact, said select parameters being selected from one or more parameters of the group consisting of 
 (1) pressure on the ultrasonic impact tool being in a range of from about 0.1-50 kg;  
 (2) ultrasonic frequency of the ultrasonic impact tool being from between about 10-800 kHz;  
 (3) amplitude of vibrations from said ultrasonic impact being from between about 0.5-120 μm;  
 (4) ultrasonic frequency of the ultrasonic impact tool and self-oscillation frequency of the ultrasonic impact tool being from between about 5-2500 Hz with a duration of ultrasonic impact being in a range of from about 2-50 vibration periods at a carrier ultrasonic frequency;  
 (5) self-oscillation amplitude of the ultrasonic impact tool being from between about 0.05-5 mm;  
 (6) a connection level between a freely axially moving indenter of the ultrasonic impact tool and a transducer of the ultrasonic impact tool acting within parameters (1)-(5); and  
 (7) free ultrasonic impacts falling within parameters (1)-(5) based on task, properties and size of the welded structure.  
   
     
     
         35 . Process of tuning ultrasonic impact for ultrasonic impact treatment of a non-detachable welded joint comprising controlling in combination parameters of free ultrasonic impact of the treatment, wherein said parameters are of pressing, amplitude, frequency, and duration of the free ultrasonic impact together with control of transducer vibrations from said impact.  
     
     
         36 . Process of structural rearrangement of a welded joint comprising subjecting at least part of the welded joint to random ultrasonic impact while controlling amplitude, length and repetition rate of said ultrasonic impact in a manner to impact energy at a repetitive rate with pauses between impacts, said pauses being sufficient for relaxation of material condition and availability for next impact with minimal resistance that does not exceed internal losses in the material when the material is in a quiet condition.  
     
     
         37 . Process according to  claim 34 , wherein the welded structure is selected from the group consisting of butt joints, fillet joints, lap joints, narrow gap joints, spot joints and apertures in a joint structure.  
     
     
         38 . Process according to  claim 35 , wherein the welded structure is selected from the group consisting of butt joints, fillet joints, lap joints, narrow gap joints, spot joints and apertures in a joint structure.  
     
     
         39 . Process according to  claim 36 , wherein the welded structure is selected from the group consisting of butt joints, fillet joints, lap joints, narrow gap joints, spot joints and apertures in a joint structure.  
     
     
         40 . Process according to  claim 34 , wherein the material properties affected are one or more properties selected from a group consisting of surface roughness and relief, radius present between surfaces, depth of groove at a weld toe line or a line between surfaces of stress concentration area, width of said groove, impact strength, plastic deformation, compressive stresses, ultrasonic fluctuating stresses, residual stress, stress corrosion, white layer/amorphous structure formation, and corrosion fatigue.