Bobbin tool friction stir welding is a new type of friction stir welding. In the study, the thermo-mechanical model of the bobbin tool friction stir welding was set up. By this model, the temperature field of AA 2014 aluminium alloy work plate of 6mm was simulated, which provides useful information for the investigation of this new process. Simulation results show that the temperature field of the cross section presents symmetry approximately about the mid thickness of the work plate. The high temperature zone has large radius at bottom and top surfaces near the shoulders while small radius at the mid thickness, like a waist. The max temperature for the point at retreating side is about 40°C higher than advancing side.

Friction Surfacing is an advanced surface modification method, so it is of great importance to study figuration mechanism of deposit in friction surfacing process for controlling deposit’s quality. By friction surfacing, consumable-rod of 1Cr18Ni9Ti (321)was surfaced on the substrate of mild steel (1020) by different process parameters (rotation speed, force and traverse speed). The effects of process parameters on deposit’s figuration are discussed. Experiments show that deposit’s width and thickness decrease linearly with increasing consumable-rod rotation speed; deposit’s width increases and its thickness decreases with increasing force. If traverse speed between substrate and consumable-rod increases, deposit’s thickness and width decrease simultaneously. According to conservation of mass, the material transferring & figuration rules in friction surfacing were analyzed, which explains the experimental results as well. So, figuration control methods of deposit in friction surfacing are set up. In practice, process parameters must be chosen properly to ensure good figuration. Only if process parameters are inside the feasible area, material can transfer fluently and deposit with good figuration could be got.

In friction surfacing process, the temperature field and strain field, especially of coating rod, is considered an important element in analyzing the process’ mechanism and choosing the key process parameters properly. In this paper, the finite element method was employed to simulate the coupling of 3-D temperature field and deformation field of coating rod during friction surfacing. The simulation results show that at the preliminary preheating period, the isotherm goes down at the center part, and the temperature field presents “M” along the radial direction. The temperature increasing rate at the friction interface is higher at first, and then become lower, once the friction system becomes quasi-steady, the temperature here will be stable approximately. The largest effective strain occurs near the center of bottom circle. The simulation results are close to the experimental results, thus builds a basis for analyzing the process’s mechanism, allows for theoretical guidance for analyzing feasibility and helps optimize key parameters.