An investigation on the tribological properties of GCr15 sliding against NM600 was carried out using a high-temperature friction and wear tester. As the temperature rose from room temperature to 300 °C, the average friction coefficient of NM600 increased rapidly, then decreased rapidly, and then became stable. The wear volume and specific wear rate of NM600 increased rapidly, then decreased rapidly, and then increased slowly. The wear mechanism and matrix properties of the tested steel at different temperatures are the main reasons for the above results. At 20–50 °C, the main wear mechanism was adhesive wear, fatigue wear, and abrasive wear. At 100–150 ℃, the wear mechanism was mainly adhesive wear, fatigue wear, abrasive wear, and oxidation wear. At 200–300 °C, the wear mechanism was mainly oxidation wear and abrasive wear.

AH36 Marine steel 10mm thick was welded by Laser-MIG hybrid welding process, and the structure and properties of the arc zone and laser zone of the Laser-MIG hybrid welding joint were studied respectively. The results show that the width of welding seam and HAZ in arc action zone is obviously larger than that in laser action zone. The microstructure of the weld was mainly acicular ferrite, bainite, martensite and grain boundary ferrite, and the content of martensite and bainite in the laser action area was relatively higher. The microstructure of the coarse grain zone is mainly thick lath martensite, granular bainite and acicular ferrite, and the microstructure of the arc action zone is relatively larger. The microstructure of the fine crystal region is mainly fine ferrite and pearlite. The hardness of arc zone and laser zone is distributed symmetrically in the weld center, the lowest hardness occurs in the weld center, and the high hardness occurs in the weld HAZ. The tensile specimens in the arc zone were fractured near the HAZ and the laser zone was fractured on the base metal far away from the weld. The lowest value of impact absorption work at 0°C in arc action area and laser action area appeared at the fusion line +0.5; the highest value of impact absorption work at 0°C in arc action area appeared at the fusion line +1.0, the fusion line +1.5, and the fusion line +2.0; the highest value of impact absorption work at 0°C in laser action area appeared at the fusion line. The impact absorption at 0°C in the laser action area is higher than that in the arc action area.

Comparative study on sliding friction and wear properties of low alloy wear-resistant steel Hardox400 and NM400 at room temperature using Retc multi-function friction and wear tester. The hardness, microstructure and wear surface morphology of the test steel were compared and analyzed by microhardness tester, optical microscope (OM) and scanning electron microscope (SEM). The results show that the wear mechanism of the two kinds of test steels is mainly manifested as abrasive wear and fatigue wear. The Martensite-Bainite Dual Phase Structure in Hardox400 has a good match of strength and toughness, and the sliding wear performance is better than the NM400 of martensite structure.

No abstract

The hardness distribution and microstructure morphology of NM400 low alloy wear resistant steel plate with thickness of 50mm and 60mm were tested and analyzed, and the sliding wear performance of typical measuring points was also analyzed. The results show that the depth of the NM400 (50mm) hardening layer is about 35mm, accounting for about 70% of the plate thickness. The depth of the NM400 (60mm) hardening layer is about 22mm, accounting for about 37% of the plate thickness. With the position of the measuring point gradually away from the surface of the steel plate, the martensite content in the microstructure of NM400 (50mm) and NM400 (60mm) gradually decreased, and the contents of pearlite, bainite and other microstructure gradually increased. The hardness of NM400 (50mm) gradually decreased from 410HV to 335HV, and the hardness of NM400 (60mm) gradually decreased from 410HV to 305HV. The micro-wear morphologies of NM400 (50mm) and NM400 (60mm) at each measuring point are mainly furrow and contact fatigue spalling, and the wear types are mainly abrasive wear and contact fatigue wear. The furrow depth and the number of furrows on the worn surface of the sample at the corresponding measuring point position gradually increased as the measuring point position moved away from the steel plate surface, and the spalling area and the depth of the spalling pit gradually increased. The wear type gradually changed from particle wear to contact fatigue wear.