INTRODUCTION The rigors of modern design require the use of material with high reliability. The high stresses in the complex stress states that are used in present-day structures are such that materials must be used to their maximum capability. There are two methods by which these structures can be designed. The first is to use large section sizes such that the stresses on the individual members are low. The second method is to use materials with exceptional mechanical properties. This latter technique is far more reasonable because it minimizes both .the weight of the structure and the cost. To get satisfactory materials, it is necessary to utilize materials melted by advanced melting techniques. One of the best materials for these critical applications is electroslag remelted (ESR), steel plates. Electroslag remelting offers an excellent combination of microcleanliness, chemical and mechanical properties uniformity, high ductility, toughness, and high reliability. Recent advances in the ESR process have made it possible to fabricate plate pattern weights up to 16,350 kg. The introduction of rectangular ESR slabs has maximized the yield from ESR melts. This process is known as Lectrefine. It is the intent of this review to present representative data for ESR steels. These data show the excellent combination of properties obtainable through this melting practice. Whenever possible, a comparison will be made between ESR steels and steels melted by other melting practices such as electric furnace, vacuum arc remelt, and vacuum induction melting. IMPROVEMENT IN MICROSCOPIC PROPERTIES Chemical Uniformity Mechanical-properties uniformity is maintained by controlling the chemical uniformity and microcleanliness. Heavy gauge plates generally exhibit fairly large segregation through the thickness. The ESR process dramatically reduces this segregation. Typical through-gauge compositions are shown in Table 1. The largest segregations occur in the C variations in Plate 1 (0.23 to 0.27) and the Si variation in Plate 2 (0. 23 to 0. 18). The other factor about the composition that should be noted is the low S. This is instrumental in maintaining the high degree of microcleanliness characteristic of ESR steels. The excellent chemical uniformity is due primarily to the melting process. Fig. 1 is a schematic presentation of a Lectrefine furnace. Melting of the electrode occurs in the flux, which is heated by a large electric current. The metal is purified by the flux as the droplets form on the electrode and drop through the flux. The molten metal in the pool solidifies rapidly. As a result of this process, there is a very fine solidification pattern and only minor macrosegregation of alloying elements occurs. The low-sulfur content of ESR steels aids in maintaining the microcleanliness of the steel. Most inclusions in steels are sulfides. When the sulfur is removed, the number of inclusions and total volume percent of inclusions is reduced. One method of optically showing the distribution of inclusions is to make a sulfur print of the steel. This process shows the distribution of sulfur through the steel.