Abstract In the forging industry, the traditional method of billet production by sawing is being replaced increasingly by shearing or cropping, as the latter offers substantial economic advantages. A considerable range of steels can be cropped satisfactorily in the cold condition for use by the forging industry. However, a number of steels of specific composition, which are used currently for hot-forged automobile components, cannot be cropped satisfactorily by the conventional cold-cropping method. This is because the billets cropped from these materials tend to exhibit stress cracks on the cropped faces, making them unsuitable for forging. This type of billet defect appears to be the most difficult to prevent, particularly as the cracks may not be visible immediately after shearing and can remain undetected for several hours/days. These delayed cracks and other billet deffects are influenced by several factors, which fall into two main groups. The first of these is metallurgical and primarily relates to the chemical compositions, existing impurities and the physical properties of the bar stocks in as-received condition. The second group consists of mechanical effects such as billet geometry, type of cropping machine and the characteristics of the tooling employed. Both groups of factors are interrelated and the proper selection of the latter is, often, guided by the former. One of the ways of producing crack-free billets is to preheat the bar stock before the cropping operation, which acts primarily to provide an increase of the material ductility and/or improved impact properties. However, it appears that current preheating practice varies widely within the forging industry without any apparent scientific basis. The present paper examines the relevant factors in order to establish their respective influence on stress cracking. Their identification is necessary if guide lines are to be established for either the efficient use of the thermal energy consumed in preheating, or possibly its total elimination through better cropping techniques and improvements in the as-recieved bar stocks.