The Study Of Wear Resistantance And Weldability Of Medium-carbon High Strength Low Alloy Steels

High-strength wear-resistant steel is widely used in ships, vehicles, constructionequipment, gears, notches and other related components. However, the wear-resistantsteel, produced in China is inferior of foreign products in strength and performance.This paper covers two aspects: firstly, the wear resistant and weldability of NM400,NM500was investigated, produced by Lianyuan Iron and Steel Co. Ltd. The domesticcomparative sample is Q345, and the foreign samples are Hardox400and SB50.Seconedly, theweldability of NM360which fed with a small amount of Ca-Mg-RE-Zr composite (1.5kg/t) by replacing Ni. The abrasion wear performance of the samples was evaluated bylaboratory wear tests (sliding abrasion test and stirring wear test). The weldabilty wascarried out by Gleeble1500. Optical microscopy and scanning electron microscopy wereutilized to observe the microstructures, worn surface and inclusions.The results showed that during the two abrasion test, the mass loss of Q345is1.5~3times compared to NM400and NM500, respectively. The worn face and massloss of NM400and NM500were similar to Hardox400and SB50. Microcutting andmicroploughing are the main wear mechanisms in the stirring abrasive test, whilescratching is the main wear mechanisms in the sliding abrasive test.The heat input were10kJ/cm，12kJ/cm，17kJ/cm in the physical simulation test tostudy the weldability of NM500. The results showed that the microstructures is bainiteand ferrite, the impact toughness is116J，82J，74J at-20oC with the different heat input.The heat input was12kJ/cm in the physical simulation test to study the weldabilityof NM360. The microstructures are bainite and ferrite in the two kinds of NM360, butthe impact toughness of the NM360which fed with Ca-Mg-RE-Zr composite (1.5kg/t)by replacing Ni is40J at-40oC, while the traditional NM360is29J. Because thecomposite cored wire induced the small inclusions formation that can pinned on thegrain boundary, which inhibited the growth of austenite so refined the grains, with thesefacts, the impact toughness of HAZ increased.