Metals

Welding deformation in crane booms presents intractable challenges in manufacturing. An innovative simulation approach, based on the inherent strain method and pre-deformation method (ISM-PDM), is proposed to control welding deformation effectively in crane booms. Furthermore, a ‘local-segment-to-global-boom’ extrapolation strategy is developed to both elucidate the evolution of deformation and identify the optimal pre-deformation magnitude. A width shrinkage of approximately 25 mm was observed in the as-welded boom segment without pre-deformation. By applying pre-deformation offsets of 10 mm and 15 mm in the width and height directions, respectively, the maximum deformation of the boom segment was suppressed by over 50%. The reliability of the proposed approach based on the ISM-PDM was validated under three conditions: a boom segment without pre-deformation, a boom segment with pre-deformation, and a full-scale boom. In all cases, the predicted deformation patterns closely matched the experimental data, with deviations not exceeding 20% of the maximum measured deformation. Furthermore, the rationality of the ‘local-segment-to-global-boom’ extrapolation strategy was validated. Together, the ISM-PDM and the local–global strategy establish a sound foundation for both welding deformation control and efficient finite element analysis of large welded box-section structures such as crane booms.

Porphyry copper–molybdenum deposits are major sources of both metals, yet efficient separation of chalcopyrite and molybdenite remains challenging, especially in the presence of pre-adsorbed collectors. This study demonstrates a surface sulfur conversion strategy using sodium metabisulfite (SMBS) to remove pre-adsorbed kerosene and restore selective depression of chalcopyrite. Micro-flotation tests show that pre-adsorbed kerosene severely impairs the depressive effect of sodium thioglycolate (STG) on chalcopyrite, resulting in poor separation performance. SMBS treatment, in combination with STG, achieves a Cu–Mo recovery differential exceeding 90 percentage points, while molybdenite floatability remains virtually unaffected. Mechanistic investigations via contact angle measurements, FT-IR, zeta potential analysis, XPS, and electrochemical characterization reveal that SMBS treatment results in a decrease in hydrophobic disulfide species and an increase in hydrophilic sulfate species on the chalcopyrite surface. This surface transformation disrupts the pre-adsorbed kerosene film, enhances chalcopyrite hydrophilicity, and facilitates subsequent STG adsorption for sustained depression. These findings establish surface sulfur conversion as a mechanistic platform for non-polar collector desorption and offer a chemically driven, environmentally sustainable approach to selective Cu–Mo flotation separation.

Fourth-generation powder metallurgy (PM) Ni-based superalloys are being developed for advanced turbine disks requiring high strength, damage tolerance, and elevated service temperatures. Rational heat-treatment design is required to reconcile high-temperature strength and tensile ductility to satisfy the ever-increasing service demands of aero-engines. This work investigates the influences of solution temperature and cooling route on 830 °C tensile behavior of a novel fourth-generation PM Ni-based superalloy under three heat-treatment schedules followed by identical aging. The results show that the 1190 °C/OQ condition achieves the highest mean elongation of 17.00 ± 0.00% and a UTS of 1093.2 ± 2.0 MPa. Increasing the solution temperature to 1210 °C under OQ raises the mean UTS to 1194.7 ± 7.3 MPa, while the mean elongation decreases to 6.67 ± 2.02%. The 1190 °C/AC condition exhibits a mean elongation of 3.83 ± 0.29% and a UTS of 1066.3 ± 7.3 MPa. EBSD and TEM reveal distinct deformation modes: grain-boundary-localized damage for 1190 °C/AC, broadly distributed intragranular plasticity for 1190 °C/OQ, and band-type strain localization for 1210 °C/OQ. The differences in tensile ductility are associated with the spatial distribution of plastic strain and grain-boundary damage resistance; neither average γ′ size nor the slip-compatibility factor m′ alone reproduces the measured ductility ranking. These findings provide a mechanistic basis for heat-treatment control of this novel fourth-generation PM superalloy.