Purpose This paper aims to anticipate the possible development direction of WAAM. For large-scale and complex components, the material loss and cycle time of wire arc additive manufacturing (WAAM) are lower than those of conventional manufacturing. However, the high-precision WAAM currently requires longer cycle times for correcting dimensional errors. Therefore, new technologies need to be developed to achieve high-precision and high-efficiency WAAM. Design/methodology/approach This paper analyses the innovations in high-precision WAAM in the past five years from a mechanistic point of view. Findings Controlling heat to improve precision is an effective method. Methods of heat control include reducing the amount of heat entering the deposited interlayer or transferring the accumulated heat out of the interlayer in time. Based on this, an effective and highly precise WAAM is achievable in combination with multi-scale sensors and a complete expert system. Originality/value Therefore, a development direction for intelligent WAAM is proposed. Using the optimised process parameters based on machine learning, adjusting the parameters according to the sensors’ in-process feedback, achieving heat control and high precision manufacturing.

Context Calcium plays a critical role in various physiological activities. However, the association between circulating calcium concentrations and mortality in a general healthy population remains undetermined. Objective To examine the association of serum calcium concentrations with all-cause and cause-specific mortality. Methods Leveraging data from the UK Biobank (n=361 662) and the US National Health and Nutrition Examination Survey (NHANES, n=36 985), we prospectively examined the association of serum calcium concentrations with all-cause and cause-specific mortality using Cox proportional hazard and restricted-cubic spline models. Results During a median follow-up of 12.0 years, UK Biobank documented 18 327 deaths, including 3119 (17.0%) from cardiovascular disease (CVD) and 9599 (52.4%) from cancer. We found a U-shape relationship of albumin-adjusted calcium concentrations with all-cause and CVD mortality. Compared to participants with moderate calcium levels (the third quintile, Q3), those with low and high levels had an increased risk of all-cause (hazard ratio [HR]=1.02 for Q1 vs. Q3; 1.10 for Q5 vs. Q3) and CVD mortality (HR=1.11 for Q1 vs. Q3; 1.25 for Q5 vs. Q3). In contrast, there was a linear positive relationship with cancer mortality (HR=1.09 for Q5 vs. Q1). Similar results for all-cause, CVD, and cancer mortality were observed in US NHANES. Conclusions Our findings provide novel insights into the association between serum calcium concentrations and mortality in the general healthy population.

In this paper, ER50-6 steel was fabricated by wire arc additive manufacturing (WAAM) with an A-W GTAW system. The microstructure, mechanical properties, and corrosion behaviors of ER50-6 steel by WAAM were studied. The results showed that, with the GMAW current increased, from the bottom to the top of the sample, the microstructure was fine ferrite and granular pearlite, ferrite equiaxed grains with fine grains at grain boundaries, and columnar ferrite, respectively. The average hardness in the vertical direction of samples 1# and 2# was 146 and 153 HV, respectively. The hardness of sample 2# increased because of the refinement of grain. The pores in the sample increased as the bypass current increased. The higher bypass current also has a deterioration effect on the corrosion behavior of ER50-6 steel.

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In this study, CoCrFeMnNiW medium-entropy alloy coating on Q235 was fabricated by plasma surfacing technology. The wear performance of the prepared one-layer coating and the two-layer coating was studied by a friction and abrasion tester. The microstructure and performance of the CoCrFeMnNiW coating were researched by optical microscope, a nano-indentation test, SEM, and hardness tester. The results show that the microstructure of the coating is made up of a fusion zone, equiaxed dendrites near the fusion zone, coarse columnar crystals, and near-surface with a certain direction between the near-fusion zone and near-surface fine equiaxed grains. The wear mechanism of one layer coating was abrasive with wear and fatigue wear. The wear mechanism of the two-layer coating was adhesive with wear and fatigue wear. For CoCrFeMnNiW MEA coating, the main factors determining their wear resistance were the value of its depth recovery ratio (ηh) and EIT.