Improving Joint Bar Service Life by Managing Residual Stress

Freight railroads in North America are seeking to improve the performance of joint bars used in bolted rail joints. Based on joint bar field experience, industry experts have indicated that increasing the load carrying capacity of bolted joints in heavy-axle-load service in continuously-welded rail territory would be highly beneficial. Three options to increase bar capacity and service life are to: (1) increase the joint bar cross-section; (2) increase material strength; or (3) induce useful residual stresses during the manufacturing process. The focus of this article is on the third option because it can be adopted with little change to the current manufacturing processes.