中厚板双丝埋弧焊冷却时间t8/5的预测外文翻译资料

Prediction of cooling time t8/5 in twin wire submerged arc welding of intermediate thickness plate

Li XiaoNinshu Malpha;Xu Xueli alpha;nd Hidekazu Murakalpha;wa

*

Abstract Twin wire submerged alpha;rc lding (SAW) is widely used in oil or galpha;s line pipe fabrication because of its high productivity. To investigalpha;te the st ngth and toughness of the healpha;t-affected zone (HAZ) in twin wire SAWthe cooling time

t8/5 of the coalpha;rse grained zone m t be studied. The authors presented alpha; method of predicting the cooling time in twin wire SAW

of intermediate thickness plate. Based on Rosenthal alpha;nalpha;lytical solutionsalpha;n energy fialpha;ctor alpha;s introduced to describe the energy contribution of the t o wiresequations of thermal cycle and cooling time in twin wire SAW of both thalpha;nd thin

pl alpha;tes were d Jeloped. Weighting factors determined by alpha;ctzomega;1 thickness and critical thickness were adopted omega; rep sent the thermal cycle and cooling time of intermediate thickness plate through linear interpolalpha;tion with thickalpha;nd thinplalpha;te solutions. The predicted cooling timer an intermediate thickness plate was verifigrave;ed experiment alpha;llyand the predicted results agreed therewith.

Key words twin wire submerged arc weldingthermal cycleanalytical solutioncooling time

o Introduction

Twin wire submerged arc welding is superior to conshy; ventional single wire SAW owing to its higher deposition rates higher welding speeds lower heat inputs lower power consumptionand reduced undercutting[ 1 -2J. It is

widely used in line pipe fabrication[3-4J bull; For twin wire

submerged arc welding used in line pipe fabricationthe role of the leading wire is to ensure sufficient penetration; the trailing wire ensures sufficient bead width to eliminate undercutting defects. The distance between the two wires

is relatively small and they always share one pool. Engishy;

neers in factories have found that the thermal cycle in twin wire SAW differs widely from single wire weldingand the cooling time t S / 5 increases markedly.

To investigate the influence of welding heat input on

the mechanical properties of the HAZ thermal and meshy;

chanical test systemssuch as the Gleeble systemare alshy;

ways used to simulate the thermal cycle during welding. Using specimens in thermal simulation experiments the

microstructure and properties of the HAZ can be stud-

ied [5 -6J bull; To improveand furthermore to guaranteethe properties of welded pipesan accurate thermal cycleesshy; pecially cooling tiacute;me t U5 must be determined before thershy;

mal simulation experiments are conducted.

There are several methods of calculating cooling time t 8/ 5 such as the finite element method (FEM)analytical equationsand experiments. Although welding thermal cyshy;

cles can be easily computed by FEMengineers and techshy; nicians in industry prefer to use simple equations to invesshy; tigate microstructure and properties in their laboratories. There are some analytical equations for the prediction of thermal cycles during the single wire arc welding process. Rosenthal s solution [7 -8J is the most popular analytical method of calculating the thermal history of welded joints. Based thereon some simple empirical equations are deshy; rived for thick platesthin platesand intermediate plates

[9 -11] under the action of single wire welding.

The analytical solution for the prediction of cooling time t 8/ 5 with a twin wire welding process has yet to be deshy;

veloped. The objective of this study was to develop simple

* Li Xiao and Xu XueliKey Laboratory of Material Processing EngineeringXi an Shiyou UniversityXi an710065. Ninshu Ma

Hidekazu MurakawaJoining and Welding Research InstituteOsaka UniversityOsaka567 -0047. Li XiaoCorresponding authorE-mail:

xli@ xsyu. edu. cn

Prediction of cooling time t 8/5 in twin wire submerged arc welding of intermediate thickness plate 25

equations for the prediction of the cooling time t8/ 5 during twin wire SAW of an intermediate thickness plate.

1 Analytical solutions

1. 1 Heat source model

Rosenthal equations present two solutions for a movshy; ing heat source and different plate thicknesses: the thin plate (2D) solutionand thick plate (3D) solution [

At a given location in a thin platewhere the distance from the heat source is rthe thermal cycle is given by eshy; quation (1)and the cooling time t 8/ 5 can be calculat1ed

by equation (2). Equation (3) and (4) can be used to

calculate a thick plate s thermal cycle and cooling time t8/ 5 respectively. Parameters in the equations are defined in Table 1.

Thin plate:

-=11 ( - }

h(4 tau;lambda;t) T omega;I v

t8/ 5 -2D = [(500 800T O )2] ( r(-;)

clude the effect of heat input of two wires and the distance between those two wires in one equationwith which the thermal cycle of twin wire SAW can he characterized accushy; rately.

(a) Thick plate (3D) (b) Thin plate (20) Fig.1 Heat source models of twin wire SAW

Table 1 Definitionunits and values of parameters

Parameter Value

Initial temperature Tol 'c

Thermal conductivity lambda; I J. S-I bull; mm- I bull; 'c -1 0.05

Thermal diffusivity alpha;

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