Industry News

I. Technological Innovation Paths in Processing

1. Breakthrough in Precision Cold Rolling

Multi-pass cold rolling with small deformation (single-pass deformation ≤12%) combined with intermediate annealing can effectively refine the grain size of austenitic stainless steel (such as 304) to below 5μm while simultaneously controlling the surface roughness to within Ra 0.8μm. One company's experience has shown that this process has increased the tensile strength of 316L bar to 760MPa, an 18% improvement over conventional processes.

2. Intelligent Control of the Hot Extrusion Temperature Field

By establishing a temperature-phase transformation coupling model, the extrusion temperature gradient of martensitic stainless steel (such as 420) can be controlled within a ±15°C range, suppressing the precipitation of delta ferrite. A combined control technology combining electromagnetic induction heating and liquid nitrogen cooling can reduce the temperature difference between the bar core and surface to as little as 30°C, significantly reducing the risk of thermal stress cracking.

II. Micro-control Mechanisms of Mechanical Properties

1. Optimizing Phase Ratios in Duplex Stainless Steel

For 2205 duplex stainless steel, by adjusting the solution treatment parameters (1050°C × 1h water quenching + 550°C × 4h aging), the ferrite/austenite ratio can be stabilized at 45:55, achieving an impact toughness of 180 J/cm² while maintaining a strength of 800 MPa. This "strength-toughness synergistic effect" has been successfully applied in the manufacture of deep-sea valve forgings.

2. Application of Grain Boundary Engineering

Adding 0.03% boron to 321 stainless steel, combined with a two-stage thermomechanical treatment (hot rolling + cold drawing + stabilization), forms uniformly distributed Ti(C,N)-B composite precipitates at grain boundaries. This design reduces the intergranular corrosion rate to 0.12 mm/year (ASTM A262-E standard), improving corrosion resistance threefold compared to conventional processes.

III. Process-Performance Co-Optimization Case Study

An aviation fastener manufacturer used a combined laser surface remelting and low-temperature plasma nitriding process to treat 17-4PH stainless steel bars, creating a 50μm-thick gradient hardening layer on the surface. Tests showed that the surface hardness reached 1200 HV0.2 (the substrate was 350 HV0.2), and the fatigue life was extended to 2.1×10⁷ cycles (at a stress amplitude of 300 MPa), successfully achieving the dual goals of a 15% weight reduction and improved reliability.