### STP824: Analytical Approaches and Experimental Verification to Describe the Influence of Cold Work and Heat Treatment on the Mechanical Properties of Zircaloy Cladding Tubes

Steinberg, E

*Engineer and physicist, Fuel Technology Division, Kraftwerk Union AG, Erlangen,*

Weidinger, HG

*Engineer and physicist, Fuel Technology Division, Kraftwerk Union AG, Erlangen,*

Schaa, A

*Engineer, Nuklearrohr GmbH, Duisburg,*

Pages: 16 Published: Jan 1984

**Abstract**

Well-controlled laboratory heat treatments were performed in the range from 460 to 610°C (733 to 883 K) and from 1 to 8 h at temperature on Zircaloy-4 cladding tubes with three different degrees of initial cold work (40%, 64%, and 76%). Within this range the influence of annealing temperature *T* and time *t* and of cold work on the yield strength *R*^{p0.2} at 400°C (673 K) and on the degree *R* of recrystallization was experimentally determined.

This data base was used to verify a semi-empirical approach to describe analytically the dependence of yield strength and recrystallization on the aforementioned technological parameters *T* and *t* for the annealing and φ = ln 1/*l*^{o} as a measure for the applied cold work.

Using a “growing function” y=lnRp0.2max−Rp0.2Rp0.2−Rp0.2min to correlate the normalized annealing temperature *A* = *t*·exp(-*Q/RT*) with the change of the yield strength *R*^{p0.2} between the values Rp0.2max and Rp0.2min, the correlation Rp0.2=Rp0.2min+ΔRp0.2·11+k·A can be obtained, where ΔRp0.2=Rp0.2min.

It was found as a good expirical approach that ΔRp0.2=c·ω4

and the yield strength can be described as Rp0.2=Rp0.2min+c·φ41+k1·φ2·A

The influence of the same mentioned technological parameters on the recrystallization can be described as R1−R=k2·ω2·A

This leads to the correlation Rp0.2=RP0.2min+c·φ41+k1k2·R1−R

between yield strength and recrystallization.

**Keywords:**

zirconium, zirconium alloys, cladding tubes, mechanical properties, elevated temperature, yield strength, recrystallization, annealing time, annealing temperature, cold work

**Paper ID:** STP34465S

**Committee/Subcommittee:** B10.02

**DOI:** 10.1520/STP34465S

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