Numerical Simulation of Temperature and Stress Fields in Medium-High Carbon Steel Surfacing

Literature Overview

This research by Yang Qingxiang, Gao Jun, Li Da, and Chen Xiaojun from Yanshan University, published in Transactions of the China Welding Institution (2006, Vol. 27, No. 5, pp. 52-56), presents a finite element analysis of the temperature and stress fields during and after the surfacing of medium-high carbon steel 60CrMnMo. The study was supported by Hebei Province Science and Technology Program (Project No. 04212201D) and the Ministry of Education Overseas Study Fund.

Research Methodology and Model Validation

The study employed a two-phase numerical simulation approach consisting of thermal analysis for the transient temperature field during surfacing and subsequent cooling, followed by stress analysis calculating transient stress fields based on the thermal results. The model was validated by comparing simulated residual stress distributions with experimentally measured values, demonstrating good agreement and confirming the predictive capability of the computational model.

Temperature Field Analysis

The thermal simulation revealed several important characteristics of heat transfer. Immediately after heat source removal at 16 seconds, the temperature distribution showed significant differences from the pre-removal state, with heat rapidly propagating toward the lower surface and boundaries. By 180 seconds, the temperature field reached equilibrium with heat transfer essentially ceasing. The peak temperature location shifted to the center of the lower surface during cooling, and the temperature gradient between inner and outer regions diminished significantly as equilibrium was approached.

Stress Field Characteristics and Engineering Implications

The stress simulation results demonstrated that peak stresses occurred at the interface between the heat-affected zone and the base metal, with sharp stress transitions observed at this boundary. Thermal stresses dominated the early cooling period, transitioning to residual stresses as the component cooled to ambient temperature.

For surfacing operations on medium-high carbon steel components such as alloy pipe fittings and pressure vessels, these findings have direct practical relevance. Preheating requirements are underscored by the high residual stresses identified near the HAZ-base metal interface, as appropriate preheating reduces thermal gradients and minimizes cracking risk. Post-weld stress relief treatment is essential for components requiring fatigue resistance, and excessive surfacing thickness increases thermal gradients necessitating careful multi-pass strategy planning. Controlled cooling after surfacing can reduce residual stress magnitudes and prevent delayed cracking in susceptible materials.

Reflections on Simulation-Experiment Integration

The successful validation of the numerical model against experimental measurements demonstrates the value of computational approaches in surfacing technology development. For engineers working with complex geometries or critical applications where experimental measurement is impractical, validated simulation models provide reliable predictions of temperature and stress fields. However, the accuracy depends on input parameter quality including material thermal properties, heat source characterization, and boundary condition definitions. Engineers should use simulation results as guidance rather than absolute predictions, supplementing computational analysis with experimental verification for critical applications. The emphasis on the HAZ-base metal interface as the critical stress concentration zone aligns with well-established welding metallurgy principles and provides a clear target for quality control efforts in surfacing operations.