The effects of cerium and titanium additions on hot cracking in welds of a Cr-Mo-V rotor steel

The Cr-Mo-V steels have been frequently used for turbine rotors in power generation facilities because of their superior high-temperature properties. When such a rotor fails during service due to cracking from fatigue, creep, or stress corrosion, there are several options one can take. One is to replace the rotor with a new one, which is the traditional approach. Another, now being used more commonly, is to repair the rotor using welding. The latter approach is considered increasingly feasible as welding techniques for rotor materials are developed, and it is attractive because the costs of weld repairs are significantly less than those of replacement. One of the difficulties in this kind of welding is the potential susceptibility of the rotor steel to various kinds of cracking. This investigation, which is part of a larger program on rotor steel welding concerns hot cracking and its mitigation. The tendency for cracking is therefore increased when alloy elements that promote the formation of low-melting liquid films are present. Other forms of cracking may also be of concern in these steels, such as delayed cracking or stress relief cracking. However, this paper is concerned with hot cracking. The results of the study are intended to provide potential ways to improve the quality of rotor welding, and especially repair welding