Showing papers on "Weldability published in 1994"

Electron Beam Welding

Abstract: Generation of the electron beam The behaviour of the electron beam on penetrating metal Welding parameters and advice on welding practice The weldability of metallic materials Preparation of the workpiece Beam and machine control Electron beam welding machines and equipment Quality levels and acceptable variations in electron beam welds Examples of electron beam welded components Personnel qualifications and machine testing Standards and regulations Other methods of working materials with electron beams A comparison of electron beam and laser welding

Solidification behavior and cracking susceptibility of pulsed-laser welds in austenitic stainless steels

Abstract: The solidification cracking susceptibility of several commercial heats of Types 304L, 316L and 321Mo stainless steels was evaluated under pulsed-laser welding conditions. Both the Suutala weldability diagram and the WRC constitution diagram predicted that all the heats tested in this investigation would be resistant to weld solidification cracking based on the individual values of their Cr[sub eq]/Ni[sub eq] ratio. Under the rapid solidification conditions imposed by pulsed-laser welding, however, a number of these resistant heats were found to be extremely susceptible to weld solidification cracking. As a result, a modified weldability diagram is proposed for austenitic stainless steels welded under conditions producing rapid solidification. The variation from predicted cracking susceptibility resulted from a shift in solidification behavior under rapid solidification growth conditions. Alloys susceptible to cracking exhibited a primary austenite solidification mode with a fully austenitic microstructure. Crack-resistant alloys were also fully austenitic, but this microstructure resulted from a massive transformation to austenite following primary solidification as ferrite. Several alloys exhibited mixed solidification modes, resulting in variable cracking susceptibility. The solidification conditions under which this shift in the primary solidifying phase occurs is reviewed in the context of the current results and previous observations.

Weldability of Ferritic Steels

Abstract: Factors influencing weldability Potential welding problem areas Solidification cracking Lamellar tearing Hydrogen cracking Reheat cracking Faults of welding Inspection for defects Joint integrity Service problems Repair.

Dynamic stresses in weld metal hot cracking

Abstract: This paper presents the results of a study aimed at understanding the influence of dynamic stresses, induced by thermal and mechanical loading, on weld metal hot cracking. The study attempts to resolve the relationship between the dynamic stress distribution in the specimen, particularly near the trailing edge of the pool, and the observed cracking behavior in a Sigmajig test specimen. The transient stress distribution in the specimen resulting from mechanical and thermal loading was calculated for a Type 316 stainless steel specimen. The initiation and propagation of the crack during welding was visually monitored using a stroboscopic vision system. The numerical results were used to understand the initiation and propagation of weld metal hot cracks during controlled welding of a specimen subjected to external restraint. The results of this study indicate that for hot cracking to occur, there exists a dynamic relationship between the metallurgical and mechanical factors, which can be influenced by the welding conditions and mechanical restraint.

Effects of alloying additions on the microstructures, mechanical properties and weldability of Fe3Al-based alloys

Abstract: Several alloys based on the Fe28Al5Cr (atomic per cent) composition were produced to study the effects of alloying with Mo, Nb, Zr, B and C on microstructures, mechanical properties, and weldability. Optical microstructures were examined before and after heat treatments of 1 h at 750 °C, as well as after selected higher temperature anneals. Tensile properties at room temperature and 600 °C and creep-rupture properties at 593 °C and 207 MPa were determined and correlated with alloying additions. Judgments as to weldability of selected alloy compositions were made by determining the hot-crack susceptibility. The results indicate that all of these properties of iron aluminides are very sensitive to alloying additions. Some combinations of the above elements resulted in refined grain sizes, increased recrystallization temperatures, and strengthening of the base alloy (through solid solution effects, as well as the formation of precipitates) in both tension and creep-rupture tests. Increased strength, however, was generally produced at the expense of room temperature ductility and weldability. The results suggest that the design of useful iron aluminide compositions will depend on the application, with the composition being modified to provide either room temperature ductility and weldability or strength, as prescribed by the intended application.

Method for producing ultra high strength, secondary hardening steels with superior toughness and weldability

Abstract: High strength steel is produced by a first rolling of a steel composition, reheated above 1100° C., above the austenite recrystallization, a second rolling below the austenite recrystallization temperature, water cooling from above Ar3 to less than 400° C. and followed by tempering below the Ac1 transformation point.

Cyclic overageing heat treatment for ductility and weldability improvement of nickel-based superalloys

Abstract: The present invention is directed to a pre-weld overageing heat treatment for nickel-based superalloys, where the alloy is heated to solutionization temperature for a time sufficient to dissolve the gamma prime phase of the alloy microstructure, then slowly cooled with periods of intermittent heating, so that the gamma prime phase reprecipitates as coarse equiaxed particles, and the presence of fine sized gamma prime phase particles is substantially avoided. The present invention is also directed to a welding method wherein said pre-weld overageing treatment is used.

Nd:YAG laser welding of coated sheet steel

Abstract: The weldability of coated sheet steels by a 2 kW Nd:YAG laser has been examined. Laser seam welds were produced in 0.75‐mm thick (23 gauge) galvanized and galvannealed sheet steels in the lap‐joint configuration. Three types of laser beam power output were used: continuous wave, sine‐wave modulated, and square‐wave modulated. The effects on weld quality of varying laser welding parameters such as welding speed, shielding gas composition, and gas flow rate were studied. Also, welds were produced with three different joint geometries: no gap between the sheets, preset gaps between the sheets, and a new joint geometry consisting of a groove projection in the top sheet of the joint. Poor‐quality Nd:YAG laser seam welds were produced in these coated sheet steels when there was no gap between the sheets of the lap‐joint. However, high‐quality seam welds could be made at welding speeds of up to 3.0 m min−1 by using preset gaps of 0.10–0.20 mm between galvannealed sheets, and up to 2.7 m min−1 by using a gap of 0.20 mm between galvanized sheets. Welds made with larger gaps (>0.20 mm) showed excessive drop‐through of the weld metal into the gap. Finally, high‐quality seam welds were produced at welding speeds up to 2.7 m min−1 using the new groove‐projection joint geometry.

High-temperature corrosion-resistant iron-aluminide (FeAl) alloys exhibiting improved weldability

Abstract: This invention relates to improved corrosion-resistant iron-aluminide intermetallic alloys. The alloys of this invention comprise, in atomic percent, from about 30% to about 40% aluminum alloyed with from about 0.1% to about 0.5% carbon, no more than about 0.04% boron such that the atomic weight ratio of boron to carbon in the alloy is in the range of from about 0.01:1 to about 0.08:1, from about 0.01 to about 3.5% of one or more transition metals selected from Group IVB, VB, and VIB elements and the balance iron wherein the alloy exhibits improved resistance to hot cracking during welding.

Method of preparing a high strength dual phase steel plate with superior toughness and weldability (LAW219)

Abstract: A high strength steel composition comprising ferrite and martensite/bainite phases, the ferrite phase having primarily vanadium and niobium carbide or carbonitride precipitates, is prepared by a first rolling above the austenite recrystallization temperature, a second rolling below the austenite recrystallization temperature; cooling between the Ar 3 transformation point and 500° C.; and water cooling to below about 400° C.

Austenitic stainless steel with low nickel content

Abstract: A new austenitic stainless steel featuring low nickel and high manganese contents is described. The steel has good weldability and is consisting, in percentage by weight, of: C: <0.1% Si: <0.5% Mn: 9.0 - 11.0% Ni: 1.5 - 3.5% Fe: balance Cu: <3.0% Cr: 16.0 - 18.0% Mo: <3.0% N: 0.10 - 0.20%

Al-Cu-Li weld filler alloy, process for the preparation thereof and process for welding therewith

Abstract: Weld filler alloys comprising aluminum, copper, lithium and, optionally, silver are disclosed which possess significantly improved fabricability and weldability. The weld filler alloys are free of magnesium and can be easily drawn into weld wire that is useful for welding aluminum-base alloys. Weldments made with the filler alloys exhibit highly improved mechanical, physical and corrosion resistance properties. The weld filler alloys may be used to weld cryogenic containers for space launch vehicles and the like.

Numerical Simulation of the Effect of Gravity on Weld Pool Shape

Abstract: Understanding the physical phenomena involved in the welding process is of substantial value to improving the weldability of materials. The intense heat and the arc inherent in fusion welding make direct experimental observation of the weld pool behavior rather difficult. Thus numerical models that can predict the processes involved have become an invaluable tool for studying welding.

Development of 590-MPa Class High Tensile Strength Steel with Superior HAZ Toughness by Copper Precipitation Hardening.

Abstract: Through the study of a chemical composition system capable of assuring high strength without impairing HAZ toughness, 590-MPa high tensile strength steel for offshore structure was developed, and its HAZ toughness improvement mechanism was clarified. The high-copper and ultra-low niobium steel provides superior HAZ toughness with medium heat input in -60°C Charpy test and -30°C CTOD test and with high input in -60°C Charpy test. Why HAZ toughness comparable to that of 490-MPa high tensile strength steel is obtained may be considered as follows. The precipitation of copper occurs much later than other precipitation-hardening elements like niobium and vanadium. Copper precipitated by tempering for strengthening goes into solid solution in the heating process of the HAZ. Copper precipitates little on cooling (and heating) during the subsequent welding thermal cycle. The embrittlement of HAZ by the precipitation hardening of copper thus does not take place. This allows the 590-MPa steel to be welded without preheating and cracking, just like 490-MPa steel.

Welding the four most popular aluminum alloys

Abstract: The fact that business is good in aluminum welding is a sure sign that more manufacturers and fabricators are using GMA and GTA welding to build new products out of this lightweight nonferrous metal. Among the most widely specified weldable grades are Alloys 6061, 5083, 5052 and 5454. A rundown on these four alloys, including properties and selected applications, is provided. Any company working with aluminum for the first time needs to know something about these four alloys. Alloys of copper-magnesium-silicon combination, of which 6061 is one, are heat-treatable. The three 5XXX series alloys, on the other hand, are nonheat-treatable. According to P.B. Dickerson, consultant, Lower Burrell, Pa., 5083, because of its high magnesium content, is the easiest of the four alloys to arc weld. Dickerson put the cut-off point in weldability at 3.5% magnesium. To prevent cracking, he added, both 6061 and 5052 require much more filler metal than do the other two alloys. Alloy 6061 consists of 0.25Cu, 0.6Si, 1.0Mg, and 0.20Cr. The main applications for 6061 aluminum are structural, architectural, automotive, railway, marine and pipe. It has good formability, weldability, corrosion resistance and strength. Although the 6XXX series alloys are prone to hot cracking, this condition canmore » be readily overcome by correct choice of joint design and electrode. The most popular temper for 6061 is T6, although the -T651, -T4, and -F temper are also popular. The -T651 temper is like a -T6 temper, only it has received some final stretch hardening. The -T4 temper has been solution heat-treated and quenched. The -F temper is in the as-fabricated condition.« less

High tensile strength steel having superior fatigue strength and weldability at welds and method for manufacturing the same

Abstract: A method for manufacturing a high tensile strength steel by normally hot rolling or control rolling following the hot rolling of a high tensile strength steel or a slab made thereof containing, in terms of weight %, 003 to 020 % of C, 06 to 20 % of Si, 06 to 20 % of Mn, 001 to 008 % of Al, 00020 % or less of B, 0002 to 0008 % or less of N, and, as required, at least one of Cu, Mo, Ni, Cr, Nb, V, Ti, Ca and REM, as well as the remaining portion of Fe and unavoidable impurities, wherein generation of fatigue cracks as welded is restrained at portions of this steel which are affected by welding heat, and development of cracks, if generated, is prevented or restrained

Weldability studies of Haynes® 230 alloy

Abstract: Weld metal solidification cracking and microfissuring in Haynes 230 and 230-W weld metals has been investigated. Simulative weldability testing to determine the susceptibility to weld metal solidification cracking was performed using the Varestraint test. Representative weldability tests, referred to as the restrained-plate and heavy-plate tests, were utilized to evaluate the tendencies for both solidification cracking and microfissuring in the fusion zone. It was found that the 230-W weld metal is more resistant to both forms of hot cracking than the 230 weld metal. The cracking susceptibility was largely influenced by the detrimental effects of boron

Weldability of Alloy 718, 625 and Variants

Abstract: The fusion zone weldability of a new alloy Inconel725 T”1. is presented and compared to Alloys 7 18,625 and Carpenter Custom Age 625 PlusTM*. Of these alloys, Inconel725 and Alloy 718 are most prone to solidification cracking during autogenous gas tungsten arc (GTA) welding as characterized by the Varestraint test. Each alloy typically forms a y/Laves terminal eutectic solidification product. In addition, other eutectics which form in some alloys include a y/MC and ‘y/M&, depending on composition. Formation of 6 (orthorhombic NigNb) adjacent to Laves and MC carbides in the interdendritic region was peculiar to Inconel 725 welds. Their possible relevance to solidification cracking tendency is discussed in terms of their volume fraction and contribution to solidification temperature range. t Inconel725 is a registered trademark of Into Alloys International. * Carpenter Custom Age 625 Plus is a registered trademark of Carpenter Technologies, Inc. Superalloys 718,625,706 and Various Derivatives Edited by E.A. Loria ‘he Minerals, Metals & Materials Society, 1994

Method of producing high strength dual phase steel plate with superior toughness and weldability

Abstract: A high strength steel composition comprising ferrite and martensite/banite phases, the ferrite phase having primarily vanadium and mobium carbide or carbonitride precipitates, is prepared by a first rolling above the austenite recrystallization temperature; a second rolling below the anstenite recrystallization temperature; a third rolling between the Ar3 and Ar1 transformation points, and water cooling to below about 400° C.

Production of high tensile strength steel with low yield ratio

Abstract: PURPOSE: To produce a steel for steel structure, having 780MPa class strength and excellent in weldability as well as in toughness at low temp., by specifically combining a steel composition with steel manufacture process conditions. CONSTITUTION: A steel, having a composition consisting of, by weight, 0.02-0.15% C, 0.15% Si, 0.6-2.0% Mn, 0.005-0.08% Nb, 0.005-0.03% Ti, 0.5-4.0% Ni, 0.005-0.08% sol.Al, and the balance Fe, is used. After heating this steel to 1000-1250 deg.C, reduction of >=50% cumulative draft is applied at a temp. between the Ac1 point and 900 deg.C. After rolling is finished, the steel is acceleratedly cooled down to 400-580 deg.C, held there for 20-100sec, and cooled down to <=200 deg.C. Subsequently, the steel is heated to a temp. in the region between the Ac1 and the Ac3 points and hardened and then tempered in the temp. region between the Ac1 point and 400 deg.C. Further, one or more kinds among 0.05-2.0% Cr, 0.05-3.0% Mo, 0.01-0.10% V, 1.0-2.0% Cu, and 0.0003-0.0020% B can be incorporated into this steel.

Weldability and properties of martensitic/austenitic stainless steel joints

Abstract: A series of studies has been carried out to examine the weldability and properties of dissimilar steel joints using martensitic and austenitic stainless steels F6NM (OCr13Ni4Mo) and AISI 347, respectively. This type of joint requires good mechanical properties, corrosion resistance, and a stable magnetic permeability in addition to a good weldability. Weldability tests include weld thermal simulation of the martensitic steel to investigate the influence of weld thermal cycles and post-weld heat treatment (PWHT) on the microstructure and mechanical properties of the heat affected zone (HAZ); implant testing to examine the tendency for cold cracking of martensitic steel; and rigid restraint testing to determine hot crack susceptibility of the multipass dissimilar steel joints. The simulation results indicated that the toughness of the martensitic steel HAZ did not change significantly after the weld thermal cycles. The implant test results indicated that welds produced using nickel based filler show...

High tensile steel having excellent fatigue strength at its weld and weldability and process for producing the same

Abstract: The present invention relates to a high tensile welded steel plate consisting essentially of, by weight, C: 0.03 to 0.20%, Si: 0.6 to 2.0%, Mn: 0.6 to 2.0%, Al: 0.01 to 0.08%, B: not more than 0.0020%, and N: 0.002 to 0.008% and optionally at least one element selected from Cu, Mo, Ni, Cr, Nb, V, Ti, Ca, and REM with the balance consisting of Fe and unavoidable impurities, and a process for producing a high tensile welded steel plate, usually comprising the steps of: subjecting a slab comprising the above chemical compositions to hot rolling or alternatively hot rolling followed by controlled rolling. The present invention enables fatigue cracking of the as-welded steel, in its heat-affected zone, to be prevented and, at the same time, the propagation of the crack to be prevented or inhibited.

Production of high strength steel pipe excellent in low temperature toughness

Abstract: PURPOSE: To produce a high strength steel pipe excellent in sour resistance, low temp. toughness and weldability by working a low alloy steel having a specified compsn. into a steel pipe and thereafter executing heat treatment by induction heating. CONSTITUTION: This steel has a compsn. contg., by weight, 0.02 to 0.09% C, <=0.6% Si, 1.3 to 2.0% Mn, <=0.015% P, <=0.010% S, 0.3 to 1.2% Ni, 0.9 to 1.2% Co, 0.1 to 0.5% Mo, 0.01 to 0.06% Nb 0.005 to 0.03% Ti, <=0.06% Al and 0.001 to 0.006% N, and the balance Fe with inevitable impurities. The steel is formed into a seamless steel pipe, an electric resistance welded pipe and a UOE steel pipe, and after that, induction heating is used from <=50 deg.C, and it is hardened under heating to the temp. range of the Ac3 point to 1000 deg.C and is subjected to tempering treatment in the temp. range of 450 deg.C to the Ac1 point. Thus, the ultrahigh strength line pipe of the API specification×100 or above can stably be produced.

Method of manufacturing austenite stainless steel

Abstract: The austenitic manganese steel having a good moldability, strength and weldability is produced by (a) hot and cool rolling a steel slab composed of at most 1.5 wt.% C, 15-35 wt.% Mn, 0.1-6.0 wt.% Al, at least one of at most 0.6 wt.% Si, at most 5.0 wt.% Cu, at most 1.0 wt.% Nb, at most 0.5 wt.% V, at most 0.5 wt.% Ti, at most 9.0 wt.% Cr, at most 4.0 wt.% Ni and at most 0.2 wt.% N, residual Fe and impurity, and (b) annealing it at 550-1000 deg.C for 5 sec. - 20 hr. The austenitic manganese steel is used for cars and electromagnetic panels.

Effect of Welding Parameters on Hot Cracking Susceptibility of Alloy 800

Abstract: The varestraint cracking test was carried out to assess the hot cracking tendency of alloy 800 at different welding conditions and augmented strain levels. The test results revealed that the hot cracking susceptibility of alloy 800 increases with increasing the heat input and augmented strain levels. This emphasizes the role of constraint either internally induced or externally applied to the welded structure.A cracking threshold or the minimum augmented strain (∈min) below which no hot cracking takes place has been found to be 0.25 for alloy 800. Also, the Critical Strain Rate to Time (CSS) required to cause cracking was found to be 6.42×10-3 sec-1 at welding condition of 100 Amp, 13 Volt and 140 mm/min.

Production of weather resistant refractory steel material for building construction, excellent in gas cutting property and weldability

Abstract: PURPOSE:To economically produce the steel material excellent in mechanical properties at ordinary temp by subjecting a steel, having a composition containing specific amounts of C, Si, Mn, P, S, Cu, Ni, Cr, Nb, Ti, etc, to rolling and to cooling under respectively prescribed conditions CONSTITUTION:A steel, having a composition consisting of, by weight, 005-013% C, 005-05% Si, 05-15% Mn, <=002% P, <=0005% S, 03-06% Cu, 005-04% Ni, 045-1% Cr, 0004-003% Nb, 0005-003% Ti, etc, is refined This steel is heated to 1050-1200 degC, and rolling is finished at 850-900 degC Then, cooling is done down to 400-500 degC at an initial cooling temp not lower than the Ar3 transformation point at (3 to 20) degC/S cooling rate