Microstructure-mechanical property relationships of dual-phase steel wire
The goal of a dual-phase steel suitable for drawing into high strength wire necessitated a study of the relation between the microstructure and properties of undrawn rod and rod drawn into wire, and of the deformation of dual-phase steel at large strains. Dual-phase steel was selected because of its pronounced strain hardening rate and superior formability. These properties permit dual-phase steel to be drawn to large strains and high strengths. Dual-phase microstructures of several different martensite volume fractions, particle shapes, particle sizes, carbon contents and crystallographic relations with the ferrite matrix were studied. It was found that good mechanical properties could be obtained in wire drawn from dual-phase steel. The most promising steel was the Fe-2Si-0.1C alloy given a double heat treatment consisting of austenitizing and quenching to martensite, followed by two phase annealing at 950 C and quenching. This steel could be drawn to a true strain of 6.1 without intermediate annealing. It is recommended that a lower carbon content of 0.06 to 0.08 wt % be used to lower the carbon content in the martensite, thereby reducing the amount of voids that form during drawing. Stress relief after wire drawing resulted in a substantial increase in the ductility of the wire. The effects of various other factors such as alloying, quench speed, drawing schedule and drawing speed on the structure and mechanical properties of the wire are discussed. 66 references, 28 figures, 9 tables.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5036079
- Report Number(s):
- LBL-17099; ON: DE84009690
- Resource Relation:
- Other Information: Paper copy only, copy does not permit microfiche production. Thesis
- Country of Publication:
- United States
- Language:
- English
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